Tag Archives: Spain

Orgasm after Vaginoplasty

Orgasm and sexual pleasure are important goals of gender reassignment surgery (GRS). Most trans women report being able to orgasm after penile-inversion vaginoplasty with clitoroplasty using the glans penis.* However, some are not able to orgasm and some report difficulty orgasming.

Two large studies found that 18% of trans women were not able to orgasm by masturbation after surgery. In one of the studies an additional 30% of the women had difficulty orgasming from masturbation.

The number of women who couldn’t orgasm went down to 14% or 15% when they included all sexual activities.

Other recent studies** have found numbers of anorgasmic women ranging from 0% to 52%, although most results were close to 18%.

It is clear that a significant percentage of trans women are not able to orgasm after this type of vaginoplasty, but it is not clear exactly how many.

SOME RECENT STUDIES OF ORGASM AFTER GRS

There were five studies where the women had clearly been sexually active:

Lawrence, 2005 – anonymous questionnaires from 232 trans women, 227 answered the question on orgasm by masturbation:

18% were never able to achieve orgasm by masturbation.

15% were rarely able to orgasm with masturbation.

15% were able to orgasm less than half the time by masturbation.

However, it seems that only 15% were completely unable to orgasm. “About 85% of participants who responded to questions about orgasm were orgasmic in some manner after SRS [GRS].” 

Imbimbo et al., 2009 – 139 trans women (93 questionnaires at clinic, 46 phone interviews):

14% of the trans women complained of anorgasmia

18% of the trans women were never able to orgasm by masturbation (out of 33 women who masturbated)

33% of the trans women were never able to orgasm by vaginal intercourse and 25% seldom orgasmed this way (out of 60 women having vaginal intercourse)

22% of the trans women were never able to orgasm by anal sex and 13% seldom did (out of 75 women having anal sex)

56 women had oral sex, but the study gives no numbers for orgasm.

Buncamper et al., 2015 – 49 trans women completed questionnaires:

10% had not had orgasm after surgery, although they had tried.

Selvaggi et al., 2007 – 30 trans women were personally interviewed by a team of experts:***

15% had not experienced orgasm after surgery during any sexual practice.

Giraldo et al., 2004  – 16 trans women were given structured interviews at follow-up visits:

0% had problems – all the women reported the ability to achieve orgasm

Note: This study is about a modification to the technique for creating a clitoris.

There is one study where 18% of the women never orgasmed after surgery, but it is not clear if they were sexually active or not:

Hess et al., 2014 – 119 trans women completed anonymous questionnaires, 91 answered the question “How easy it is for you to achieve orgasm?”:

18% said they never achieve orgasm

19% said it was rarely easy for them to achieve orgasm

The other studies above asked about sexual activity or gave the women an option to say the question did not apply or they had not tried. This one did not.

On the other hand, some people did not answer the question, so perhaps women who were not sexually active skipped the question on orgasm.

There are three studies that only give brief information on how many women could orgasm; it is not clear what is going on with the rest of the women.

Perovic et al., 2000 – 89 trans women were interviewed:

It looks like 18% had not experienced orgasm during vaginal sex, but it is possible that some of the women were not sexually active.

“Information on sensitivity and orgasm was obtained by interviewing the patients; the sensitivity was reportedly good in 83, while 73 patients had experienced orgasm.”

and

“If the penile skin is insufficient, the creation of the vagina depends on the urethral flap, which also provides moisture and sensitivity to the neovagina. The results of the interviews showed that orgasm was mainly dependent on the urethral flap.”

Goddard et al., 2007 – 70 trans women were interviewed by a telephone questionnaire; 64 of them had had a clitoroplasty:

It looks like 52% of the women with clitorises were not able to achieve clitoral orgasm, but again it is not clear if they were sexually active.

“Clitoral sensation was reported by 64 patients who had a neoclitoris formed and 31 (48%) were able to achieve clitoral orgasm.”

14% of the women complained of “uncomfortable clitoral sensation.”****

Wagner et al. (2010), – 50 trans women completed a questionnaire:

It looks like between 17% and 30% were not able to achieve clitoral orgasm.

“Of the 50 patients, 35 (70%) reported achieving clitoral orgasm” but

“90% of the patients were satisfied with the esthetic results and 84% reported having regular sexual intercourse, of whom 35 had clitoral orgasm.” 

If we look only at the group having regular intercourse, 17% of them are not having clitoral orgasms. But were the women not having intercourse masturbating and unable to orgasm? If so, they were also sexually active and the 30% number is the relevant one.

The study gives very little information on the questionnaire and results, but it seems surprising that 83% of the women were having clitoral orgasms from sexual intercourse; that is not typical in cis women.

A final study asked about pleasurable sexual intercourse, not orgasm:

Salvador et al., 2012 – 52 trans women participated in the study. It is unclear how they were surveyed, but based on this earlier study, it could have been a combination of a questionnaire and interview.

8% did not consider vaginal sex pleasurable.

However, only one woman said sexual intercourse was unsatisfactory (2%) while 10% of the women said it was average; presumably some of the women who said it was average also said it was pleasurable and some did not.

About Orgasms

Freud believed that women had vaginal and clitoral orgasms; unfortunately he also believed that vaginal orgasms were superior and mature women should give up clitoral orgasms. In the 1960s Masters and Johnson showed the physiological basis for clitoral orgasms in the lab; they argued that orgasms during intercourse were also clitoral orgasms, just harder to achieve. More recently, some sexologists have shown that some women have G-spot orgasms during intercourse, although not all experts believe in them.

For most women it is easiest to have an orgasm from masturbation or clitoral stimulation. Most women are not able to have clitoral orgasms during vaginal intercourse without additional clitoral stimulation. Some women experience other types of orgasms during vaginal intercourse.

Although trans women’s biology is somewhat different from cis women’s, their clitorises are formed from the most sensitive area of the penis. Therefore, we might expect trans women to have orgasms most easily from masturbation of the clitoris; the study by Imbimbo et al. that compares different sexual activities supports this hypothesis.

It also makes sense that when we look at orgasms from all sexual activities, we find more trans women are able to orgasm than when we look at just clitoral orgasms; some trans women may be having G-spot orgasms involving their prostate gland.

Interestingly, Imbimbo et al. found that it was easier for trans women to have orgasms from anal sex than vaginal sex (65% of the women often had orgasm from anal sex, 35% seldom or never did; 42% of the women always or often had orgasm from vaginal sex and 58% seldom or never did). Furthermore, more of the trans women were having anal sex than vaginal sex (54% versus 43%). Perhaps they had more experience with anal sex before surgery or perhaps anal sex worked better for some women.

Studies that simply ask about orgasm without talking about what type of orgasm or sexual activity is involved do not give enough information about what is happening. Future studies that include this information would make it easier to compare the results and to improve outcomes.

Comparing the Studies

It is difficult to compare the results of the studies. The studies are of surgery at different clinics around the world; the work is being done by different surgeons and may involve variations in technique. Some of the surgeries are more recent than others as well.

In addition, the studies use different methodologies to collect data and they do not ask the same questions. Some are focused on clitoral orgasms, others talk about orgasm during intercourse, some studies talk about masturbation, and some are vague about what they mean by orgasm.

As is common in follow-up studies, almost all of the studies had a significant drop-out rate; not everyone who had the surgery participated in the study. This could create a bias in either direction – people who regret the surgery might be too depressed to respond to the clinic or people who were dissatisfied might be more motivated to participate in the study.

The method of the study could also introduce biases; people may be more likely to tell the truth in an anonymous survey than in an interview. On the other hand, interviews may allow for follow-up questions and clarifications.

With only 10 studies that are so different it is impossible to come to any definitive conclusions about orgasm after GRS. I like to believe that Goddard et al.’s numbers of anorgasmic women are so high because some of them were sexually inactive or because their study included women 9-96 months after surgery. It could also be something to do with their surgical technique. After all Perovic’s et al.’s study also included women 0.25-6 years after surgery and some of them may have been sexually inactive, but their numbers were much better.

I suspect that the reason all of Giraldo et al.’s patients were orgasmic is that their sample size is so small, but again, it could be that they have a superior technique.

It might be that Buncamper et al. had better numbers than most of the studies because their patients had surgery more recently with improved techniques, but it might also be because their study was smaller.

With so few studies, I could find no clear pattern based on when people had surgery, how data was collected, or follow-up time after surgery. For further information on the studies, see this appendix.

What is clear is that we need more research on patients who are not able to orgasm after surgery. Are some people more at risk than others? Does the surgical technique make a difference? What role does aftercare play?

Is being non-orgasmic just a possible complication of the surgery? If so, how common is it?

And most important, what can be done to enable all trans women to be able to orgasm after surgery?

 

 

 

*I did not find data on orgasm after intestinal vaginoplasty. According to this 2014 review of studies, most studies of intestinal vaginoplasty did not look at sexual function; for those that did the review reports a score for sexuality rather than information on orgasms.

** I have excluded studies published before 1994 and studies where all of the surgeries were performed before 1994. The studies by Imbimbo et al. and Selvaggi et al. may include some participants who had surgery before 1994.

*** The exact number of the participants is unclear because this study is one of a pair using the same participants. The other study by de Cuypere et al. did in-depth interviews with 32 trans women while this one focused on testing the sensitivity of the genitals for 30 trans women. Unfortunately, the de Cuypere study reports data in terms of how many women “Never-sometimes” had orgasm so their data is not comparable to other studies. (They found that 34% of the women never-sometimes had orgasm during masturbation and 50% never-sometimes had orgasm during sexual intercourse.)

**** Goddard also reports that despite problems, “no patient elected to have their clitoris removed.” Is the man mad?

Transsexualism and Anorexia Nervosa: A Case Report – Review

This is a somewhat surprising case report of a trans man (born female) who developed anorexia nervosa after sex reassignment surgery.

The 24-year-old patient had surgery to remove his breasts, ovaries, and uterus. Afterwards he began binging and purging. He had not had problems with eating behaviors or weight loss before surgery.

This case is similar to the trans woman (born male) in this study who began to diet excessively after sex reassignment surgery. It is, however, different from this trans man who stopped dieting once he was on hormones and menstruation ceased.

The authors suggest that the eating disorder is an “expression of a gender identity process, or a conflict of an acceptance of one’s own sexuality.”

It is easy to understand why someone with gender dysphoria might dislike their body and develop problems eating, but in this case, the patient had already changed his body.

Why did the eating disorder develop after physical transition was complete?

Had he been focused on changing his body with hormones and surgery and then when he was done, he focused on his shape?

Was his eating disorder a sign of persistent body dissatisfaction no matter what he did?

The authors suggest that the patient’s underlying problems may have caused the eating disorder:

“In this case, there was clearly a linkage between a lack of sense in self-efficacy and a body dissatisfaction that continued after the sex change surgery. Discomfort with her/his own body appeared to be more deeply anchored than just being rooted in the wish to change the physical appearance.”

Alternatively, might the surgery have caused an abrupt shift in hormones that led to an eating disorder? More importantly, could adjusting his hormones help him recover from the eating disorder?

We think of testosterone and estrogen as sex hormones, but they are much more than that. Like all hormones, they are part of a complex system of chemicals that affect each other. Specifically, we know that “sex” hormones also play a role in appetite.

“The sex hormones estrogen, progesterone and androgens are involved in the complex regulation of appetite, eating and energy metabolism. In most species, including man, food intake and reproductive functions are closely linked. Thus, during the different hormonal phases of the menstrual cycle daily food intake varies and, moreover, remarkable physiological adaptations of appetite and body composition occur during pregnancy and lactation. In addition, regulation of eating behaviour and metabolic functions by sex hormones is of considerable general importance for women’s health, as indicated by the disturbances in this regulation associated with a number of clinical disorders.”

From “Sex hormones, appetite and eating behaviour in women.”

In this case study, the patient’s estrogen levels would have dropped significantly after his ovaries were removed. In addition, doctors normally reduce the dose of testosterone after surgery, although to a level typical for a man.

Women eat less during the phase of the menstrual cycle when estrogen levels are high, so it is possible that a drop in estrogen levels would be connected to eating more.

Furthermore, bulimia may be connected with polycystic ovary syndrome (PCOS), a syndrome which is characterized by elevated androgen levels.

Testosterone stimulates appetite and high circulating levels of this androgen in women have been associated with impaired impulse control, irritability and depression, i.e., common features of women with bulimia. Accordingly, it has been proposed that elevated levels of androgens may promote bulimic behaviour by influencing craving for food and/or impulse control. Hypothetically, bulimia may, in some cases, have a hormonal, rather than a psychiatric etiology, a suggestion supported by the observation that antiandrogenic treatment reduces bulimic behaviour. This may turn out to be a novel and valuable approach to treating women with BN, particularly those with hyperandrogenic symptoms.

From “Sex hormones, appetite and eating behaviour in women.”

The patient in this case study had symptoms that are typical of bulimia, binging and purging. Perhaps in his case the bulimia was related to the sudden drop in estrogen after surgery coupled with male levels of testosterone.

Most people do not develop eating disorders after sex reassignment surgery. There would have to be other factors involved, possibly genetic or psychological.

We have very little data on eating disorders and gender dysphoria, just a set of case studies.

However, we now have two cases of trans people developing an eating disorder after having surgeries that would have changed their hormones.

In one case, a trans woman began restricting her eating after surgery; in her case the surgery would have decreased her testosterone levels and thus, possibly decreased her appetite.

In this case, a trans man began binging and purging after surgery which would have decreased his estrogen levels and thus, possibly increased his appetite.

We need more research into this question. Do changes in hormones trigger eating disorders in some trans people? Most of all, can we use this to find a way to help trans people with eating disorders?

 

Original Source:

Transsexualism and Anorexia Nervosa: A Case Report by Fernando FernÁndez-Aranda, Josep Maria Peri, Victor Navarro, Anna BadÍa-Casanovas, Vicente TurOacuten-Gil,& Julio Vallejo-ruiloba in Eating Disorders: The Journal of Treatment and Prevention, Volume 8, Issue 1, 2000 pages 63-66.

 

More details on the patient:

After surgery, the patient had “2-4 weekly binge episodes with daily vomiting and abuse of laxatives and diuretics.”

He was overly concerned with being fat and wished to be thinner so his body shape wouldn’t look female.

He was moderately underweight, but then “during the last six months, he lost more than 15 kg [33 pounds] of body weight through restricting food intake.”

The Eating Attitudes Test, Eating Disorders Inventory, Body Attitudes Test, and Body Shape Questionairre showed “severe eating pathology and negative body experience.”

The patient also had problems with alcohol and drug abuse, self-mutilation, and suicide attempts, but these had begun at age 17.  He was diagnosed with “gender identity disorder, alcohol dependence, anorexia nervosa (purging subtype), major depression (Axis I), and borderline personality disorder (Axis II).

The patient’s father had obsessive-compulsive disorder and one of his sisters had an affective disorder.

As a child, the patient felt like a boy, didn’t play with girls, tried to hide any feminine parts of his silhouette, and hated feminine features of his body.

Genes and Gender Dysphoria

Twin and family studies suggest that there may be a genetic component to gender dysphoria. Researchers have naturally been trying to find genes linked to gender dysphoria.

Most of the research has focused on genes that are known to be related to sex hormones in some way.

I. Researchers may have found genes related to gender dysphoria in trans men (born female).

A large Spanish study found an association between the gene for Estrogen Receptor β and gender dysphoria, but a medium-sized Japanese study did not.

A small Austrian study found an association between gender dysphoria and a different gene related to converting progesterone into androgens. Nobody else has looked at this gene.

A possible flaw with the Austrian study is that the control females were seeking help with perimenopausal issues; it may be that their genes were different from the general public.

Both of these results need to be replicated.

It is also possible that the genes were related to sexual orientation.

In the Spanish study, all of the trans men were attracted to women; it is likely that 95% of the control women were attracted to men.

The Austrian study does not talk about sexual orientation, but typically most trans men are attracted to women and most women are not.

Many control women also had the genetic variations found in trans men. Some other genes or environmental factors must also be involved.

These results need to be replicated. The Austrian study was relatively small and possibly flawed while the Spanish and Japanese studies contradict each other.

II. Researchers thought they had found genes related to gender dysphoria in trans women (born male), but larger studies did not replicate the results. It is possible, however, that the genes related to gender dysphoria are different in different populations.

Four studies looked at genes related to sex hormones, specifically genes for estrogen receptor β, androgen receptor, and CYP19A1. CYP19A1 encodes aromatase, an enzyme involved in turning androgens into estrogens.

None of the studies found a relationship between gender dysphoria and the gene for CYP19A1.

Three studies found no difference in the gene for estrogen receptor β; the study that found a difference was much smaller than the others.

Three studies found no difference in the gene for androgen receptor, including one study of over 400 trans women.

III. An Italian study that looked at the Y chromosome found no differences between trans women and control males.

IV. An Austrian study that looked at sex chromosomes in trans women and trans men found no significant abnormalities.

V. A Japanese study that looked at genes related to estrogen receptor alpha and progesterone receptor found no differences between the genes of male to female transsexuals and male controls or the genes of female to male transsexuals and female controls. This study also looked at estrogen receptor β, androgen receptor, and CYP19A1 and found no differences for those genes either; this is one of the studies discussed above.

VI. An Austrian study of a gene related to steroid 5-alpha reductase (SRD5A2) found no differences between trans women, trans men, and male and female controls. SRD5A2 is involved in the conversion of testosterone to dihydrotestosterone.

It is important to remember that there may be some other genetic variations that are linked to gender dysphoria in trans women, something that we haven’t studied yet.

At this point, however, we do not seem to have found genes related to gender dysphoria in trans women.

Recommendations for future research:

Look at genes other than the ones related to sex hormones or sex chromosomes. Perhaps the cause of gender dysphoria is different from what we expect.

Control for sexual orientation by including some cis lesbians and gay men in the study.

Study trans people with African ancestry – and other groups that have not yet been studied. Studies so far have looked at people from Spain, Italy, Japan, Austria, America and Australia (Caucasian only), and Sweden.

For more details on the studies, see the links and comments below.

STUDIES OF TRANS MEN (Born female)

2014:

The (CA)n Polymorphism of ERβ Gene is Associated with
FtM Transsexualism – This Spanish study compared the genes of 273 female to male transsexuals and 371 control females. As in the study of trans women below, they focused on three variable regions of genes: estrogen receptor β (ERβ), androgen receptor, and CYP19A1 which encodes aromatase, an enzyme involved in turning androgens into estrogens.

They found no connection between the genes related to androgen receptors or aromatase, but they did find an association between the ERβ gene and gender dysphoria in trans men.

“The repeat numbers in ERβ were significantly higher in FtMs than in control group, and the likelihood of developing transsexualism was higher (odds ratio: 2.001 [1.15-3.46]) in the subjects with the genotype homozygous for long alleles.”

Three caveats:

All the trans men participating in the study had gender dysphoria that began before puberty and were attracted to women (i.e. members of their biological sex). The control females were probably 95% straight. It is possible that the genetic difference they found is related to sexual orientation, not gender identity.

This is not an absolute difference, it is a difference in frequency – 69% of the trans men had the long allele for ERβ, but so did 59% of the control women. Some other genes or environmental factors must also be involved in gender dysphoria (or sexual orientation).

The study below found different results; however, this study was larger.

note: All participants in the study were of Spanish origin.

2009:

Association study of gender identity disorder and sex hormone-related genes.

This Japanese study compared 74 male-to-female transsexuals, 168 female-to-male transsexuals, 106 male controls, and 169 female controls. They looked at genes for androgen receptor, estrogen receptors alpha and beta, aromatase, and progesterone receptor.

They found no differences between the genes of male to female transsexuals and male controls or the genes of female to male transsexuals and female controls. 

“The present findings do not provide any evidence that genetic variants of sex hormone-related genes confer individual susceptibility to MTF or FTM transsexualism.”

The abstract does not provide any information on the demographics of the trans women and trans men.

The results of this study for ERβ contradict the results of the Spanish study. The Spanish study looked at 273 trans men while this study only looked at 74, so it is unlikely that the Spanish study is simply wrong.

It may be, however, that this study is still right, at least in Japan. People in different countries have different genes; they may have different genes for gender dysphoria.

It is possible that cultural differences or medical policies may mean that clinics in different countries are looking at groups of people with different problems.

Finally, gender dysphoria might be caused by different factors or combinations of factors in different cultures. Japanese trans men may be different from Spanish trans men in some important way.

2008:

A polymorphism of the CYP17 gene related to sex steroid metabolism is associated with female-to-male but not male-to-female transsexualism.

This Austrian study compared 102 male to female transsexuals to 756 male controls and 49 female to male transsexuals to 915 female controls.

A possible flaw in this study is that the females controls were women seeking help with perimenopausal disorders; they may have had genes that were different from the general population. The male controls, on the other hand, were “participating in a health prevention program.”

Since the results found that the frequency of a particular mutation was different in female controls from all of the other groups, it matters a great deal if the control females are significantly different in some other way from the other participants.

This study looked at a different gene from the other studies, CYP17. CYP17 encodes cytochrome, an enzyme involved in converting progesterone and pregnenolone into androgens.

The authors found that a particular mutation of this gene, CYP17 −34 T>C, was associated with female to male transsexualism, but not male to female transsexualism.

They also found that, “the CYP17 −34 T>C allele distribution was gender-specific among controls. The MtF transsexuals had an allele distribution equivalent to male controls, whereas the FtM transsexuals did not follow the gender-specific allele distribution of female controls but rather had an allele distribution equivalent to MtF transsexuals and male controls.” 

In other words, trans men and trans women were similar to male controls and not female controls.

They point out, however, that there were women without gender dysphoria who had the mutant allele as well as women with gender dysphoria who did not have it. “Thus, carriage of the mutant CYP17 T−34C SNP C allele is neither necessary nor sufficient for developing transsexualism.”

In other words, there must be other genetic or environmental factors involved.

They do not discuss the sexual orientation of the participants in the study. As discussed above, it is possible that most of the trans men were attracted to women and that this genetic mutation is related to sexual orientation, not gender identity.*

Finally, I keep coming back to the female control group. What if converting progesterone to androgens is related in some way to perimenopausal symptoms? What if the mutant gene protects against problems in menopause somehow and so the female control group includes fewer people with this gene?

2007:

A common polymorphism of the SRD5A2 gene and transsexualism. This Austrian study compared 100 trans women, 47 trans men, 755 control men, and 915 control women. They looked at a mutation of the steroid 5-alpha reductase gene (SRD5A2); this gene produces an enzyme that catalyzes the conversion of testosterone to dihydrotestosterone.

They found no differences between any of the groups. The mutant allele was not associated with transsexualism and its distribution was not gender specific among controls.

This study has the same flaw as the 2008 study listed above; the control females were all seeking help for problems with perimenopause.

2002:

Sex chromosome aberrations and transsexualism. This Austrian study looked at the chromosomes of 30 trans women and 31 trans men. They did not find significant abnormalities, although they suggested further investigation might be worthwhile.

“We could not detect any chromosomal aberrations with the exception of one balanced translocation 46,XY,t(6;17)(p21.3;q23). Importantly, no sex chromosomal aberrations, which would be detectable on the G-banded chromosome level, have been observed.”

They conclude:

“The data described here provide evidence that genetic aberrations detectable on the chromosome level are not significantly associated with transsexualism. In addition, molecular-cytogenetic FISH analyses did not reveal deletions of the androgen receptor gene locus on chromosome Xq12 or of the SRY locus on chromosome Yp11.3. Multiplex PCR analyses demonstrated one AZF deletion in a male-to-female transsexual.”

but:

“However, the detection of one carrier of a Y chromosome microdeletion out of 30 male-to-female transsexuals could argue for further investigations. This is of special interest in light of the recent discussion of gamete banking before hormonal and sex reassignment surgery of transsexuals.”

 

STUDIES OF TRANS WOMEN (Born male)

The Y Chromosome:

2013

Hormone and genetic study in male to female transsexual patients. This Italian study looked at six areas on the Y chromosomes of 30 trans women. They found no abnormalities.

“This gender disorder does not seem to be associated with any molecular mutations of some of the main genes involved in sexual differentiation.”

The trans women were aged 24-39 and had already begun hormone therapy. A little over half of them had already had sex reassignment surgery and the rest were waiting for it.

2002:

Sex chromosome aberrations and transsexualism. This Austrian study looked at the chromosomes of 30 trans women and 31 trans men. They did not find significant abnormalities, although they suggested further investigation might be worthwhile.

For further details, see the description above under trans men.

Genes Related to Sex Hormones:

2007:

A common polymorphism of the SRD5A2 gene and transsexualism. This Austrian study looked at a mutation of the steroid 5-alpha reductase gene (SRD5A2. They found no differences related to gender or gender identity. For more details, see the description above in the section on studies of trans men.

The following studies looked at the same areas of genes related to sex hormones.

Initially, a small Swedish study of trans women (born male) found a difference in the length of the estrogen receptor β repeat polymorphism, but none of the other studies did.

Similarly, an American-Australian study found that trans women had longer repeat lengths for the androgen receptor allele, but none of the other studies did.

It looks like these genes do not affect gender dysphoria in trans women, although it is possible that different genes affect people in different countries.

2014:

Association Study of ERβ, AR, and CYP19A1 Genes and MtF Transsexualism – This Spanish study compared the genes of 442 trans women and 473 control males. They focused on three variable regions of genes: estrogen receptor β, androgen receptor, and CYP19A1 which encodes aromatase, an enzyme involved in turning androgens into estrogens.

They found no connection between these genes and gender dysphoria.

Interestingly, 98% of the trans women had chromosomes that were 46,XY, i.e. normal, but 2% of the group showed aneuploidy, or abnormal chromosomal numbers. This is slightly higher than usual.

The abstract does not go into detail, but presumably the aneuploidies were cases of Klinefelter syndrome; a condition where a person typically has one Y chromosome and two X chromosomes. Most people with Klinefelter’s syndrome identify as male, but there may be a higher than usual occurrence of gender dysphoria among people with Klinefelter’s.

There are no details on the trans women in the abstract; however, the same researchers did a very similar study of trans men (see above). It may be that the participants in the two studies were screened in the same way.

2009:

Association study of gender identity disorder and sex hormone-related genes.

This Japanese study compared 74 male-to-female transsexuals, 168 female-to-male transsexuals, 106 male controls, and 169 female controls. They looked at genes for androgen receptor, estrogen receptors alpha and beta, aromatase, and progesterone receptor.

They found no differences between the genes of male to female transsexuals and male controls or the genes of female to male transsexuals and female controls. 

“The present findings do not provide any evidence that genetic variants of sex hormone-related genes confer individual susceptibility to MTF or FTM transsexualism.”

The abstract does not provide any information on the demographics of the trans women and trans men.

Androgen receptor repeat length polymorphism associated with male-to-female transsexualism.

This Australian and American study compared 112 male to female transsexuals to 258 control males. They looked at genes for androgen receptor, estrogen receptor beta, and aromatase. No differences were found for the estrogen receptor or aromatase, but transsexuals had longer repeat lengths for the androgen receptor allele.

“This study provides evidence that male gender identity might be partly mediated through the androgen receptor.”

This result was not found in the Spanish study or the Japanese study above. The Spanish study was larger than this one. Thus, this result has not been replicated.

However, it is possible that this genetic variation is connected to gender dysphoria for Caucasian trans women in America and Australia, but not in Spain or Sweden and not for Japanese trans women.

It is also possible that the genetic difference found here is related to sexual orientation, not gender identity. The researchers in this study only knew the sexual orientation for about 40% of the participants in the study, but people with gender dysphoria are much more likely to be attracted to people of the same biological sex than people without gender dysphoria.

As in the Spanish, study above, this is not an absolute difference, it is a relative one. There were also cis men who had long AR repeat lengths (Figure 1). Again, some other genes or environmental factors must also be involved in gender dysphoria (or sexual orientation).

The trans women in this study were all Caucasian; 76 of them were from an Australian clinic and 36 of them were from UCLA in America. Almost all of them were on hormones. Some of them had gender dysphoria in childhood. “The sexuality is only known for approximately 40% of patients, because some patients did not wish to discuss or disclose this information or the patient’s sexuality was flexible and not easily classified.”

2005:

Sex steroid-related genes and male-to-female transsexualism.

This Swedish study compared the genes of 24 male to female transsexuals and 229 male controls. They looked at specific areas in the androgen receptor gene, the aromatase gene, and the estrogen receptor β gene.

They did not find a difference between male-to-female transsexuals and men for the first two genes, but they did find a difference related to the gene for estrogen receptor β. “Transsexuals differed from controls with respect to the mean length of the ERβ repeat polymorphism.”

In addition, “binary logistic regression analysis revealed significant partial effects for all three polymorphisms, as well as for the interaction between the AR and aromatase gene polymorphisms, on the risk of developing transsexualism.” 

The study was very small, however, and as the authors said, “results should be interpreted with the utmost caution.”

The three more recent studies above did not replicate the findings of this study. The other studies were much larger than this one, so it is possible that these results were a fluke.

It is also possible, that the genes linked to gender dysphoria in Sweden are different from the genes linked to it in other countries.

The authors of the American-Australian study described above say, “Our sample size was approximately four times larger than that of the Swedish study, so it is possible that the former study was underpowered to detect a false positive. Alternatively, there might be differences between Swedish and non-Swedish populations in this polymorphism. In the Swedish study, the long repeat occurred in 51.8% of control subjects and 67.1% of transsexuals, whereas in the present study the long repeat occurred in 36.5% of control subjects and 44.1% of transsexuals. Thus, although there was a trend in the same direction in both studies, there are major differences in prevalence of these long repeats between the two populations.”

The only data we have on the participants in the study are that the trans women were Caucasian and the vast majority of the controls were also Caucasian. Again, it is likely that there was a higher percentage of people attracted to male in the group of trans women than the general population; this might have affected the results.

As the authors point out, “the gene variants investigated in this study are relatively common, none of the studied variants could hence be assumed to be the primary cause of this condition.” Rather, genes might increase or decrease the chance of developing gender dysphoria.

So, if the results of this study are not a fluke, we are still left with the questions of what other factors contribute to developing gender dysphoria and is this a gene related to gender dysphoria or sexual orientation in Sweden?

The end result of all this:

We have a couple of possible candidates for genetic variations related to gender dysphoria in trans men, but we need further studies. We need to replicate the results and to control for sexual orientation. In the case of the CYP 17 gene, we need to compare trans men to healthy control females instead of women with perimenopausal issues.

We don’t have any strong candidates for genetic variations related to gender dysphoria in trans women. Future studies might do well to look for genes that are not related to sex hormones. As always, they should control for sexual identity. (This should be done by adding lesbians and gay men without gender dysphoria, not by excluding trans women who are attracted to women from the studies. See my rants in articles on brain sex.)

 

*A group of trans women would include many more people attracted to men than a group of control males, but typically about half of trans women are attracted to women while most trans men are attracted to women. Thus this could be a comparison of two groups (control males and trans men) where a large majority of the people are sexually attracted to women, one group where half the people are attracted to women (trans women), and a group where about 5% of the people are attracted to women (control females).

White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study – Review

This study compared the white matter in the brains of males, females, and female to male transsexuals (FtM).*

This is one of a set of studies; another one looked at the white matter in the brains of male to female transsexuals (MtF) .

White matter is the stuff in your brain that transmits signals from one area to another. It is mostly made up of glial cells and axons. Glial cells are cells in the brain that aren’t nerve cells; they’re like a support system for the nerve cells. Axons are the long skinny part of your nerve cells that transmit information.

In three fasciculi (bundles of nerve fibers), FtM transsexuals had white matter that was like males and different from females.

In the corticospinal tract, FtM transsexuals’ white matter microstructure pattern was between the pattern of the male and female controls.

The study does not say if there were any other ways in which FtM transsexuals’ white matter was different from both males and females without gender dysphoria. I think they did not look at the question; they seem to have analyzed the data first to find sex differences and then to compare FtM transsexuals to the other groups in those areas.

It would be beyond interesting and relevant to find any areas of the brain in which people with gender dysphoria were different from people without gender dysphoria.

It is worth noting that the FtM transsexuals were all sexually attracted to females while the females were all attracted to males and the males were all attracted to females.

Thus the study was also comparing the brains of two groups of people attracted to males and one group of people attracted to females. The differences they found could be related to sexual orientation.

It is not clear what these differences mean, what caused them, or what their significance would be in brain function.

You can stop here if you just want the gist of the results. Otherwise, back to the study:

The study found sex differences in the fractional anisotropy (FA) values of white matter in four bundles of nerves with males having a higher FA value. The white matter structures with a higher FA value for males were the anterior** and posterior parts of the right superior longitudinal fasciculus, the forceps minor (right), and the corticospinal tract.***

In three of these four nerve areas, FtM transsexuals had FA values that were significantly larger than females and not significantly different from males.

In the inferior corticospinal tract, FtM transsexuals had FA values that were significantly larger than females and significantly smaller than males.

The authors conclude:

“…the main result of our study is that untreated FtM transsexuals differed from control females in two associative fasciculi (superior longitudinal fasciculus and forceps minor) and in the corticospinal tract. In contrast they only differed from control males in the corticospinal tract. These findings indicates that prior to hormonal cross-sex treatment the white matter microstructure of associative fascicles in untreated FtM transsexuals is more like that of individuals with the same gender identity than of individuals with the same biological sex.”

Their fascicles are also more like that of individuals with the same sexual orientation. We can not conclude that the cause is their gender identity, at least not from this data. We need more research in this area.

It is worth noting that we do not know what exactly made the white matter microstructures develop the way they did. It could be due to hormones or experience or an interaction of the two.

In addition, the microstructure in FtMs might have been affected by a different factor than the microstructure in males.

Finally, in the case of the corticospinal tract, it is possible that FtM transssexuals had white matter that developed like the control males, but then something caused their FA values to decrease. Changes in FA values can be due to age or illnesses, including depression or excessive alcohol consumption.

What do the differences they found mean practically?

This study found a sex difference in the FA values for the following fasciculi (bundles of nerves):

Superior longitudinal fasciculus (right, anterior and posterior) – a pair of long bundles of neurons connecting the front and back of the cerebrum (cerebrum=most of your brain). It is connected to many parts of the brain. One of its functions is to integrate auditory and speech nuclei.

Forceps minor (right) – a fiber bundle that connects that lateral and medial surfaces of the frontal lobes of the brain. It is part of the corpus collosum. The corpus collosum is responsible for interhemispheric sensory and auditory connectivity.

Corticalspinal tract (right) – connects the brain to the spinal cord. It is responsible for voluntary movement.

Looking at these descriptions, this study found sex differences in the nerves that connect the front and back of the brain, the nerves that connect the two hemispheres, and nerves that connect the brain to the spinal column.

It’s hard to predict how differences in these parts of the brain would affect men’s and women’s cognitive abilities and personalities.

The difference was found only on the right side of the brain. Does this mean anything? Maybe. According to the authors:

“Regarding brain laterality, we found that all the FA value decreases in women compared to men are seen in the right hemisphere. Similar asymmetries are also reported by Schmithorst et al. (2008), they described lower FA values in girls than in boys, and although there were decreases on both sides, the largest lost FA value clusters were on the right, indicating a right hemispheric predominance in sex differences. More recently Huster et al. (2009), focusing on the midcingulum bundle, found lower FA values in the right hemisphere than in the left and in women than in men.”

What specifically is the difference they observed in these bundles of nerves? What are FA values?

In another study, the authors say that FA values are “related to the ordered arrangement of myelinated fibers” and “an indication of white matter coherence and axonal integration.” Wikipedia says that FA is thought to reflect fiber density, axonal diameter, and myelination in white matter.

So finding higher FA values for males in certain bundles of nerves could mean that they have more dense nerve connections there or that those nerve connections are fatter or that they have more or fatter myelin sheaths. It might mean that the nerve connections in those bundles are more orderly, coherent, and integrated.

The next question, of course, is what does it mean if you have more or fatter or more coherent nerve connections between the front and back of your brain? between the two hemispheres? going to your spine?

Or, to look at it in terms of function, if the white matter responsible for voluntary movement is more coherent in males, it might give them faster reflexes. On the other hand, what does it mean if the white matter that connects auditory and speech nuclei is more coherent in males? It sounds like it ought to make it easier for males to process language.

My basic conclusion from all this is that we have found a sex difference in the brain, but we don’t really know what it means.

The authors try to connect their findings to differences in spatial abilities and verbal fluency, because the superior longitudinal fasciculus is “involved in the integration of inputs from multiple modalities and is a component of the network for spatial awareness that plays a major role in the visual and oculomotor aspects of spatial function such as spatial attention and spatial working memory.”

It might be, but there are a lot of other cognitive functions that use the integrations of inputs from multiple modalities. We have no way of knowing if the connections they observed were for spatial ability or giving a speech or cooking dinner without burning yourself.

I think they are overreaching in their conclusion here.

The authors also discuss the difference they found in the forceps minor. Again, I think it’s hard to know what exactly a sex difference here would mean; the forceps minor connects the two halves of the prefrontal cortex which controls our behavior. Does having more connectivity on the right make men better at controlling themselves or integrating their emotions?

The forceps is part of the corpus collosum. Another study found differences related to sexual orientation in this area of the brain. It is important to make sure that any differences found in this study are not due to sexual orientation.

The authors refer to a study which found that the shape of the corpus collousm in transsexual individuals matched their gender identity not their biological sex. I can only see the abstract of that study, so I don’t know if they looked at the sexual orientation of the people in that study.

Anyhow, here is the discussion of the forceps minor by the authors:

“The forceps minor connects, via the genu of the CC, orbitofrontal regions ( Park et al., 2008) involved in emotional functions and behavioral control. Kringelbach and Roll (2004), suggested that orbital cortex activity is related to the reward value of reinforcers and punishers.

The forceps minor is a part of the anterior region of the corpus callosum. The CC is the major interhemispheric pathway in the human brain and integrates sensory, motor, cognitive and emotional functions from both hemispheres; the isthmal area of the CC is larger in homosexual than in heterosexual males ( Witelson et al., 2008). FA values in the anterior part of the CC change during development ( Lebel et al., 2008). In a sample of children and adolescents, it was reported that girls have lower FA values than boys in the anterior CC region ( Schmithorst et al., 2008). In addition, the boys had lower FA values than girls in a small region of the splenium. We did not observe differences in the splenium between adult male and female controls.

There are only a couple of studies on the transsexual CC. Studying the CC shape, it was concluded that the shape in transsexuals is more similar to their gender identity than to their biological sex ( Yokota et al., 2005). However, when the whole CC surface was studied no differences in CC -regardless of genetic sex or gender- were reported (Emory et al., 1991). Our results cannot be compared to these works, which used surface measurements, while we have used FA analysis, which seems to be a more suitable technique for detecting microstructural white matter differences.”

The authors say less about the corticospinal tract, but they mention that genes and motor experience interact in its development. This is an area where FtM transsexuals were in-between male and female controls, so perhaps they are suggesting that the males had more practice at motor skills.

Of course all of the sex differences found in this study could be related to experience or an interaction of genes and experiences.

The authors of this study imply that the sex differences they found were caused by hormones early in development, but we can’t actually know that.

This study had a couple of serious weaknesses.

1. They did not look for any general differences between the brains of trans and cis people, they only looked at how trans men compared to males and females in areas where they found a sex difference. This assumes that gender dysphoria is caused by something related to hormones – which is what the authors want to prove.

It would be helpful if future studies look at both issues – sex differences and general differences between cis and trans people. Perhaps the authors could of this study would be able to use the data they collected to do this.

2. They did not include any cis lesbians as control groups, although all of the FtM transsexuals were attracted to women. Without doing this, we can not be sure if the similarities between the FtM transsexuals and cis men attracted to women are caused by gender identity or sexual orientation.

The study also has some strengths.

1. They used only trans men who had not yet taken hormones. We know that taking cross-sex hormones changes your brain. (Early studies of gender identity and the brain used people who had already been on hormones.)

2. They tested the actual hormone levels of the FtMs before the brain scans. A Japanese study found that many of the trans men who came to their clinic had poly-cystic ovarian syndrome (PCOS). PCOS can lead to elevated levels of androgens which would confuse the results.

3. Everyone in the study was right-handed.

Original Article:

White matter microstructure in female to male transsexuals before cross-sex hormone treatment. A diffusion tensor imaging study by Rametti G, Carrillo B, Gómez-Gil E, Junque C, Segovia S, Gomez Á, Guillamon A in J Psychiatr Res. 2011 Feb;45(2):199-204.

* I am following the language used in the study to refer to trans men and control subjects.

** The abstract says that the white matter was different in the medial and posterior parts of the superior longitudinal fasciculus, but  in the text of the study, the results discuss the anterior and posterior parts. Anterior and posterior refer to front and back while medial means in the middle, so it makes more sense to talk about the anterior and posterior parts of the nerve bundle. I think they made an error in the abstract.

***A later study of white matter in MtF transsexuals found a sex difference in the same three bundles of nerves. They found a sex difference in three additional areas as well: the left superior longitudinal fasciculus, the right inferior front-occipital fasciculus, and the left cingulum. It’s not clear why one study found more sex differences in white matter than the other did. (The earlier study was done by the same people using the same methodology but different control groups.)

 

P.S. A fun link on the map of the connections of white matter in young men’s brains.

The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study – Review

This study compared the white matter in the brains of males, females, and male to female transsexuals (MtF).*

White matter is the stuff in your brain that transmits signals from one area to another. It is mostly made up of glial cells and axons. Glial cells are cells in the brain that aren’t nerve cells; they’re like a support system for the nerve cells. Axons are the long skinny part of your nerve cells that transmit information.

MtF transsexuals were similar to males, not females, in the volume of gray matter, white matter, and cerebrospinal fluid in their brains.

In five fasciculi (bundles of nerve fibers), MtF transsexuals had white matter that was different from both males and females. MtF transsexuals’ white matter microstructure pattern fell halfway between the pattern of male and female controls.

The study does not say if there were any other ways in which MtF transsexuals’ white matter was different from both males and females without gender dysphoria. I think they did not look at the question; they seem to have analyzed the data first to find sex differences and then to compare MtF transsexuals to the other groups in those areas.

It would be beyond interesting and relevant to find any areas of the brain in which people with gender dysphoria were different from people without gender dysphoria.

It is worth noting that the MtF transsexuals were all sexually attracted to males while the males were all attracted to females and the females were all attracted to males.

Thus the study was also comparing the brains of two groups of people attracted to males and one group of people attracted to females. The differences they found could be related to sexual orientation.

It is not clear what these differences mean, what caused them, or what their significance would be in brain function.

You can stop here if you just want the gist of the results. Otherwise, back to the study:

The study found sex differences in the volumes of gray matter and white matter in the brain as well as the volume of cerebrospinal fluid (CSF); males have larger volumes than females. They found that the MtF transsexuals had volumes similar to the males and significantly different from the females. In this respect, MtF transsexuals have brains more like male’s than female’s.

The study also find sex differences in the fractional anisotropy (FA) values of white matter in six bundles of nerves with males having a higher FA value. The white matter structures with a higher FA value were the left and the right superior longitudinal fasciculus, the right inferior front-occipital fasciculus, the left cingulum, the forceps minor, and the corticospinal tract.

An earlier, related study of white matter in FtM transsexuals found a sex difference in the white matter in three of the same bundles of nerves: the right superior longitudinal fasciculus, the forceps minor, and the corticospinal tract. They did not report a sex difference in the left superior longitudinal fasciculus, the right inferior front-occipital fasciculus, or the left cingulum. (The earlier study was done by the same people using the same methodology but different control groups.)

In five of these six nerve bundles, the MtF transsexuals had white matter that was significantly different from both males and females. Their FA values fell in-between the values for males and females. In the inferior frontooccipital fasciculus their FA values were also different, but the difference was not statistically significant.

What does this mean?

First of all, it is important to note that for three of the six nerve bundles, the sex difference was not found in another closely related study. It may be that only the sex differences in the right superior longitudinal fasciculus, the forceps minor, and the corticospinal tract are real. The authors do not address this question (they should have).

In any case, the authors conclude that “the white matter microstructure pattern in untreated MtF transsexuals falls halfway between the pattern of male and female controls. The nature of these differences suggests that some fasciculi do not complete the masculinization process in MtF transsexuals during brain development.”

There are other possible explanations, however:

1. MtF transsexuals who are attracted to males might have had different experiences from both males and females. For example, they might have played soccer more than most girls but less than most boys. Similarly, the observed sex differences might have been caused by differences in experiences for girls and boys. This article argues that the superior longitudinal fasciiculus is changed by musical expertise.

2. MtF transsexuals might have had fasciculi that developed like the control males, but then something caused their FA values to decrease. Changes in FA values can be due to age or illnesses, including depression or excessive alcohol consumption. In this model, a lower FA value for females could be due to sex differences, while the lower value for MtF transsexuals might be due to later problems damaging the white matter.

3. There might be two completely separate pathways that cause males and MtF transsexuals to have higher FA values than females – or that cause females and MtF transsexuals to have lower FA values than males.

4. There might be some other confounding variable like left-handedness that affects white matter. The authors do not say if their subjects were right- or left-handed, but transsexuals are more likely to be non-right-handed than the general population.

5, The differences in the white matter in different nerve bundles might have different causes. For example, males might have a higher FA value for white matter connecting the brain to the spinal column due to playing sports, while their white matter in another region was affected by hormones.

We can’t conclude anything about what it means that the MtF transsexuals had FA values between males and females. We don’t know what caused the differences. What we do know is that MtF transsexuals were different from both males and females.

We also don’t know what the sex differences they found mean at a practical level.

This study found a sex difference in the FA values for the following fasciculi (bundles of nerves):

Superior longitudinal fasciculus (right and left) – a pair of long bundles of neurons connecting the front and back of the cerebrum (cerebrum=most of your brain). It is connected to many parts of the brain. One of its functions is to integrate auditory and speech nuclei. An earlier study only found a sex difference in the right superior longitudinal fasciculus.

Forceps minor (right) – a fiber bundle that connects that lateral and medial surfaces of the frontal lobes of the brain. It is part of the corpus collosum. The corpus collosum is responsible for interhemispheric sensory and auditory connectivity.

Inferior fronto-occipital fasciculus (right) – a nerve bundle that goes from the frontal lobe along the caudate nucleus and corona radiata, it also goes into the occipital and temporal lobes. One of its functions is to integrate auditory and visual association cortices with the prefontal cortex.  An earlier study by the same authors did not find a sex difference in this fasciculus. This is also the nerve bundle that was not significantly different for MtF transsexuals.

Corticalspinal tract (right) – connects the brain to the spinal cord. It is responsible for voluntary movement.

Cingulum (right) – a collection of white matter fibers that go from the cingulate gyrus to the entorhinal cortex. One of its functions is to integrate executive function nuclei. It allows the parts of the limbic system to communicate with each other. The limbic system is involved in emotion, behavior, motivation, long-term memory, and the sense of smell. An earlier very similar study did not find a sex difference in the cingulum.

Looking at these descriptions, this study found sex differences in the nerves that connect the front and back of the brain, the nerves that connect the two hemispheres, nerves that go from the front lobe into the occipital and temporal lobes, nerves that connect the brain to the spinal column, and nerves that connect the parts of the limbic system.

The difference does not seem to be related to any particular part of the brain.

The difference was found mostly on the right side of the brain. Does this mean anything?

If we only include the sex differences that were found in both this and the earlier study of FtM transsexuals, all of the sex differences were on the right side of the brain. We would still be looking at nerves that connect the front and back of the brain, nerves that connect the two hemispheres, and nerves that connect the brain and spinal cord.

It’s hard to predict how a difference in so many parts of the brain would affect men’s and women’s cognitive abilities and personalities.

What specifically is the difference they observed in these bundles of nerves? What are FA values?

They authors say that FA values are “related to the ordered arrangement of myelinated fibers” and “an indication of white matter coherence and axonal integration.” Wikipedia says that FA is thought to reflect fiber density, axonal diameter, and myelination in white matter.

So finding higher FA values for males in certain bundles of nerves could mean that they have more dense nerve connections there or that those nerve connections are fatter or that they have more or fatter myelin sheaths. It might mean that the nerve connections in those bundles are more orderly, coherent, and integrated.

The next question, of course, is what does it mean if you have more or fatter or more coherent nerve connections between the front and back of your brain? between the two hemispheres? going to your spine?

Or, to look at it in terms of function, if the white matter responsible for voluntary movement is more coherent in males, it might give them faster reflexes. On the other hand, what does it mean if the white matter that connects auditory and speech nuclei is more coherent in males? It sounds like it ought to make it easier for males to process language.

My basic conclusion from all this is that we have found a sex difference in the brain, but we don’t really know what it means.

The authors of the study don’t see it that way. They try to connect what they’ve found to sex differences in spatial abilities and verbal fluency, because the superior longitudinal fasciculus “connects complex cortical regions that subserve higher cognitive functions.” The problem with that logic is that there are a lot of cognitive functions being processed in the cortex.

I think they are overreaching a great deal there.

Anyhow, here is part of their discussion of their results and how they relate to the brain:

“MtF transsexuals differed from male and female controls in the right and the left superior longitudinal fasciculus. The SLF connects complex cortical regions that subserve higher cognitive functions and that are sexually dimorphic. Sex differences in cognition are consistently found in spatial abilities and verbal fluency ( Kimura, 1999); males outshine females in the former but the females outshine males in the latter. It has been reported that the performance of untreated MtF transsexuals in mental rotation tasks is consistent with that of their biological sex ( Haraldsen et al., 2003 Slabbekoorn et al., 1999 ). Schöning et al. (2010) studied spatial cognition using fMRI and found that untreated and treated MtF transsexuals had increased activation in the temporo-occipital regions and decreased activation in the left parietal lobe compared to control men. We have investigated brain activation during mental rotation in chronically hormone treated MtF transsexuals. These MtF transsexuals present less activation than male controls in the superior parietal lobe (Brodman’s area 7) and higher activation than females in the superior part of the gyrus frontalis (Brodman’s area 9) ( Carrillo et al., 2010). Interestingly, these two cerebral regions are connected by the SLF ( Makris et al., 2005Hua et al., 2009 ).

We found significant differences between MtF transsexuals and male and female controls in the forceps minor and the anterior region of the cingulum, both in the right hemisphere. The forceps minor connects orbitofrontal regions ( Park et al., 2008) and the cingulum is an associative bundle that runs from the anterior temporal gyrus to the orbitofrontal cortex ( Catani and Thiebaut de Schotten, 2008) and both form part of the emotional networks ( Kober et al., 2008 ). There is evidence that the orbitofrontal cortex and anterior cingulate cortices are involved in reinforcement processing and the reward value of reinforcers and punishers ( Cohen, 2008 Kringelbach and Rolls, 2004 ). Moreover, it has been suggested that the anterior cingulated cortex relates current information with an extended history of reward ( Walton et al., 2007).

The FA values of the corticospinal tract in MtF transsexuals also differed from male and female controls. Studies performed in non-human primates ( Lemon, 2008) have shown that this tract is a descending motor pathway originated from several cortical regions (primary motor cortex, premotor cortices, supplementary motor area and cingulate motor area, primary somatosensory cortex, posterior parietal cortex and the parietal operculum). Limb movements that require a high degree of skill and flexibility are controlled by these motor fibers. Lesions of this tract affect fine sensoriomotor function of the hand ( Lemon and Griffith, 2005). The maturation of the corticospinal tract depends on motor experience and genetic factors ( Cheeran et al., 2009 Martin et al., 2007).”

 

Original Article:

The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study by Rametti G, Carrillo B, Gómez-Gil E, Junque C, Zubiarre-Elorza L, Segovia S, Gomez Á, Guillamon A. in J Psychiatr Res. 2011 Jul;45(7):949-54. 

* I am following the language used in the study to refer to trans women and control subjects.

P.S. A fun link on the map of the connections of white matter in young men’s brains.

Effects of cross-sex hormone treatment on cortical thickness in transsexual individuals – Review of Abstract

This is an interesting study that found that taking cross-sex hormones changed the thickness of the cortex in the brain.

I have only been able to see the abstract; the study was published in May 2014 and I do not have access to it.

The study looked at 15 trans men (born female) before and after they took testosterone for at least six months. They also looked at 14 trans women (born male) before and after they took androgen blockers and estrogens for at least six months.

They found that :

“After testosterone treatment, FtMs (trans men) showed increases of CTh bilaterally in the postcentral gyrus and unilaterally in the inferior parietal, lingual, pericalcarine, and supramarginal areas of the left hemisphere and the rostral middle frontal and the cuneus region of the right hemisphere. There was a significant positive correlation between the serum testosterone and free testosterone index changes and CTh changes in parieto-temporo-occipital regions. In contrast, MtFs (trans women), after estrogens and antiandrogens treatment, showed a general decrease in CTh and subcortical volumetric measures and an increase in the volume of the ventricles.”

In other words, taking testosterone makes certain areas of your brain thicker and more testosterone changes your brain more.

Blocking testosterone and taking estrogens makes certain areas of your brain shrink. According to the abstract, this makes the ventricles get bigger – the ventricles are a network of cavities in the brain that contain cerebrospinal fluid.

We already know that there are sex differences in the thickness of the brain’s cortex, although we don’t know exactly what they mean. (You can read more about cortical thickness and what it might mean here.)

Thus study suggests that some of the sex differences we observe in the brain are related to the hormones in our bodies. Our brains are not set in stone by pre-natal exposure to hormones.

For transgender people this study shows that hormone therapy will change your brain.

It does not tell us what that will means in terms of changes in thoughts, feelings, or behaviors.

It’s also not clear if the changes in the trans women’s brains are caused by reducing the testosterone level or adding estrogen or both.

The abstract does not discuss whether the changes caused by the cross-sex hormones make the brain more “masculine” or “feminine” or neither.

It looks like this study is a follow-up to an earlier study, Cortical Thickness in Untreated Transsexuals. The earlier study found that before hormone therapy there were differences between transsexuals and control groups.

The differences the authors found in their earlier study were fairly complicated:

“We would suggest that transsexuals do not show a simple masculinization (FtMs) or feminization (MtFs) of their brains—rather, they present a complex picture in their process of sexual differentiation depending on the brain region studied and the kind of measurements taken.”

In other words, there were some ways in which trans men have brains like cis men’s and some ways in which their brains are like cis women’s while trans women have brains that are like cis women’s in some ways and like cis men’s in others.

One caveat to the pre-hormone part of the study – the authors only included people who were “erotically attracted to subjects with the same anatomical sex.” Thus, it is possible that the brain differences they observed were caused by sexual orientation, not gender identity.

Many studies of gender identity and the brain make this mistake. For example, they will compare a group of trans men who are attracted to women to a group of cis men who are attracted to women and a group of cis women who are attracted to men. It makes it impossible to be sure if any differences between the brains of trans men and cis women are due to gender identity or sexual orientation.

Studies of gender identity and the brain should include control groups of lesbians and gay men as well as straight people.

In any case, the current study shows that taking cross-sex hormones will further change the brain.

Original Article (Abstract):

Effects of cross-sex hormone treatment on cortical thickness in transsexual individuals by Zubiaurre-Elorza L, Junque C, Gómez-Gil E, Guillamon A in J Sex Med. 2014 May;11(5):1248-61.

Related blog post – Increased Cortical Thickness in Male-to-Female Transsexualism – A Review and a Hypothesis.

Facial Feminization Surgery: The Forehead. Surgical Techniques and Analysis of Results – Review

This is an abstract that has been published online before the print version. I cannot find the full article yet.

This is a study of facial feminization of the forehead done on 172 patients over a four year period (2008-2012). It describes surgical techniques. They analyzed the results in terms of how the foreheads had changed. They also surveyed the patients on their satisfaction. The results are not actually given in the abstract.

The study seems to have been done by the people who did the surgery.

More later.

Original Abstract:

Facial Feminization Surgery: The Forehead. Surgical Techniques and Analysis of Results by Capitán L, Simon D, Kaye K, Tenorio T, in Plast Reconstr Surg. 2014 Jun 18. [Epub ahead of print].