Sex Reassignment Surgery Demographics in the Netherlands

Our favorite folks in Amsterdam have provided data set on MTF transsexuals receiving SRS in their clinic covering 40 years. The paper is openly available online, not behind a paywall, so you may read it for yourself. But I have a few observations and comments regarding the data and the authors’ comments.

First, let’s look at the data, reorganized into putatively HSTS vs. AGP. (Yes, given all we know about MTF transwomen, I will assume that all non-exclusively androphilic transwomen are AGP.)

Table 1

Demographics of transgender women undergoing primary genital gender-affirming surgery at the authors’ institution between January 1980 and January 2020

Demographics	Total	Vaginoplasty	Orchiectomy	GCV
Number	n=1531	n=1468	n=44	n=19
Age at surgery (SD=1)	33 (25–44)	33 (24–44)	32 (26–45)	54 (45–60)
Sexual orientation (self report) n=	699	645	42	12
HSTS n= (%)	372 (53)	357 (55)	13 (31)	2 (17)

As the authors noted, “Individuals who opted for GCV (vulvaplasty only, no vaginoplasty) were generally older, had no history of puberty suppression, and were more frequently sexually oriented towards women.” The same could be said for orchiectomy as well. HSTS are must more likely to want/need vaginoplasty over other possible choices as one would expect, so as to be able to have vaginal intercourse with men.

The authors made a comment that I found ahistorical. They believe that GCV is a relatively new procedure. It is not. In fact, Christine Jorgensen had GCV only in 1952, as reported by her surgeon, Dr. Christian Hamburger, as neither of them desired to facilitate sex with men. Similarly, “orchies”, as we called them back in the 1970s, was common for both HSTS and AGP in the early 20th through the mid- to late-20th Century due to greater ease of obtaining them. (Some of this was due to the Eugenics Movement, which was only too happy to sterilize “perverts”.)

Finally, the authors wrote about encouraging “fertility preservation” but seem to lament that it isn’t possible for those who begin puberty blockers early, “The increase in individuals starting puberty suppression at early pubertal stages, when serum testosterone concentrations are insufficient for spermatogenesis, may lead to an increase in individuals without options for preservation of fertility.” This strikes me as “unclear on the the concept” as why would such MTF early transitioners, who are all HSTS (as even this clinic’s own data attests), want or need to cryostore sperm. Just who will they impregnate, their future husbands?

Reference:

Van der Sluis, et al., “Surgical and demographic trends in genital gender-affirming surgery in transgender women: 40 years of experience in Amsterdam”, British Journal of Surgery, Volume 109, Issue 1, January 2022, Pages 8–11, https://doi.org/10.1093/bjs/znab213

American Psychiatric Association Supports The Two Type Transsexual Taxonomy

Very frequently, I and others are challenged with claims that the two type taxonomy of transsexuality had been “debunked”.  When I show that that isn’t true, my interlocutors said something to the effect that, “Well, I’ll go with the American Psychiatric Association (APA) over your fringe science.”  They were assuming that the APA had “debunked”, or otherwise disavowed, the taxonomy.  Nothing could be further from the truth as we explore what APA documents show; most critically, how the Diagnostic & Statistical Manual of Mental Disorders, Revision Five (DSM-5) explains and supports the taxonomy and describes the two types.

But first, we need to explore a bit of nomenclature and its history.  Over the decades, the two types have been given different labels:

Homosexual         Non-Homosexual / Autogynephilic or Autoandrophilic
nuclear                  non-nuclear / marginal
core                        non-core / marginal
Ego-syntonic         Ego-dystonic
Androphilic           Gynephilic (for MTF only, the reverse is used for FtM)
True-                        Pseudo-
Primary                   Secondary
Group One              Group Three (Anne Vitale 2001) (For MTF only, “Group Two” for FtM)
Early Onset            Late Onset
Young                      Older  Transitioner
Early                        Late Transitioner
Transkid                 Adult

Most people who have recently learned of the taxonomy ascribe it to just one researcher, Dr. Ray Blanchard.  While he was a prolific publisher of studies of the taxonomy, he did NOT discover or create it.  He did, however, coin one of the terms used to describe one of the types, “autogynephilic” (AGP) to fully and correctly articulate their nature and the role of autogynephilia in the etiology of their gender dysphoria.  He contrasted this type with the description of the sexuality of the other type, using the then common convention of describing transsexuals’ sexual orientation based on their natal (biological / “assigned at birth”) sex, as “homosexual transsexual” (HSTS).

So, when exploring APA documents, we need to keep in mind that for MTF transsexuals, “homosexual” = “early onset” and “autogynephilic” = “late onset”.

Thus HSTS/AGP = early onset / late onset taxonomy.

I know that some will object and falsely claim that this is not the equivalent taxonomy or theory.  But we have examples of scientific papers where they are used interchangeably.  And more importantly, in the DSM-5 itself, the description and explication of the two types make it very clear that they are the same taxons and theory.  There can be no honest quibbles.  The DSM-5 fully documents, describes, and supports as our best current scientific understanding, the two type taxonomy and theory.

First, the DSM-5 defines (and thus acknowledges the existence of) autogynephilia in its glossary of technical terms on page 818,

“autogynephilia Sexual arousal of a natal male associated with the idea or image of being a woman.”

This definition is literally the same as Blanchard articulated.  One cannot say the APA has “debunked” the existence of autogynephilia when they helpfully define it for use by their members and the public.

But let us continue.  One of the key points of the two type taxonomy is that autogynephilia is often expressed as sexual arousal to cross-dressing, and though not always, it can be progressive and lead to gender dysphoria.  The DSM-5 describes this very phenomena in its description of ‘transvestic disorder’ on pages 703-4,

“Transvestic disorder in men is often accompanied by autogynephilia (i.e., a male’s paraphilic tendency to be sexually aroused by the thought or image of himself as a woman).  Autogynephilic fantasies and behaviors may focus on the idea of exhibiting female physiological functions (e.g., lactation, menstruation), engaging in stereotypically feminine behavior (e.g., knitting), or possessing female anatomy (e.g., breasts). … Some cases of transvestic disorder progress to gender dysphoria. The males in these cases, who may be indistinguishable from others with transvestic disorder in adolescence or early childhood, gradually develop desires to remain in the female role for longer periods and to feminize their anatomy.”

One could not get a more clear description of the progression of autogynephilic cross-dressing to gender dysphoric transwoman.

The DSM fully describes and supports the two type taxonomy of gender dysphoria as can be found starting on page 455,

“In both adolescent and adult natal males, there are two broad trajectories for development of gender dysphoria: early onset and late onset. Early-onset gender dysphoria starts in childhood and continues into adolescence and adulthood; or, there is an intermittent period in which the gender dysphoria desists and these individuals self-identify as gay or homosexual, followed by recurrence of gender dysphoria. Late-onset gender dysphoria occurs around puberty or much later in life. Some of these individuals report having had a desire to be of the other gender in childhood that was not expressed verbally to others. Others do not recall any signs of childhood gender dysphoria. For adolescent males with late-onset gender dysphoria, parents often report surprise because they did not see signs of gender dysphoria in childhood.  Adolescent and adult natal males with early-onset gender dysphoria are almost always sexually attracted to men (androphilic). Adolescents and adults with late-onset gender dysphoria frequently engage in transvestic behavior with sexual excitement. The majority of these individuals are gynephilic or sexually attracted to other posttransition natal males with late-onset gender dysphoria. A substantial percentage of adult males with late-onset gender dysphoria cohabit with or are married to natal females. After gender transition, many self-identify as lesbian. Among adult natal males with gender dysphoria, the early-onset group seeks out clinical care for hormone treatment and reassignment surgery at an earlier age than does the late-onset group. The late-onset group may have more fluctuations in the degree of gender dysphoria and be more ambivalent about and less likely satisfied after gender reassignment surgery.  In both adolescent and adult natal females, the most common course is the early-onset form of gender dysphoria. The late-onset form is much less common in natal females compared with natal males. As in natal males with gender dysphoria, there may have been a period in which the gender dysphoria desisted and these individuals self-identified as lesbian; however, with recurrence of gender dysphoria, clinical consultation is sought, often with the desire for hormone treatment and reassignment surgery. Parents of natal adolescent females with the late-onset form also report surprise, as no signs of childhood gender dysphoria were evident.”

Note the full concurrance with the description of “early onset” gender dysphoria begining in childhood, persisting into adulthood and their sexual orientation as being “homosexual” with respect to their natal sex.  Note the description of “late onset’ as having the opposite sexual orientation as “early onset”, and then in natal males, “transvestic behavior” (an expression of autogynephilia) as a precursor to their gender dysphoria.  One could not get a more definitive proof of the APA’s acknowledgement and support for the two type taxonomy as the actual text from the DSM-5.

Further Reading:

Minority Report: APA Transgender Taskforce

Reference:
DSM-5

Sorry Virginia, The Two Type Trans Typology Has NOT Been Disproven

A new study out of Europe is being touted by some autogynephilic autogynephilia denialists as proving that there aren’t two types.  In this case, they want to show that autogynephilia is just as common in exclusively androphilic transwomen as it is in exclusively gynephilic and bisexual transwomen.  Sorry Virginia, the two type taxonomy has NOT been disproven.  The actual DATA, not the text of the study, clearly supports the taxonomy.

First, recall that there is much noise in any study, much of it because of Social Desirability Bias.  There is a strong tendency for transwomen to mis-report their sexuality.  A number of gynephilic/bisexual transwoman falsely claim to be exclusively androphilic, often ignoring their own sexuality (e.g. ignoring years of sexual experience with women, including having been married to women).

First, lets look at their three categories and their age of HRT onset.

Sexuality:        Gynephilic                Bisexual                 Androphilic

N=                          15                              26                              17

Age of HRT           37.8                          31.8                            30.0

(SD) years             8.3                             8.4                             8.7

Do those numbers make any sense given nearly every other study we’ve ever seen?  Consider that in the Nuttbrock study, half of the androphilic transwomen had begun HRT before the age of 20 years old while less than 10% of the bisexual had.  Another issue is the range (Standard Deviation) in years of the age of starting HRT where it is similar to the other two, but slightly wider.  Can this be a hint that some of the putatively androphilic were years younger when they started HRT, but a fair number of older transwomen pulled the age up?  As in an older, non-exclusively androphilic transwoman?  As though to confirm this, we note that in the demographics table, two of the putatively androphilic transwomen were married, one now divorced.  Ummmm… so that’s at least three out of the 17 we know are mis-reporting their sexuality.  Two more are cohabitating, living with a lover, but the study doesn’t let us know if it is with men or with women.  Another suspicious data point is that six of the 17 reported that their first sexual partners were women and another two were still sexually naive, that is, virgin, analloerotic (“asexual” = not androphilic) leaving only nine who might be androphilic.  So here is a Bayesian style statistical prior:  I’m betting that at least eight of the 17 transwomen can be proven to not be exclusively androphilic and that the data regarding how many report being autogynephilic will reflect that.  In fact, I’m betting that nearly all of those in this study, save two or three, are in fact BISEXUAL, given their age of HRT onset.  Because of that, I’m betting that we will see data that will look very much like what we see in other studies, that gynephilic transwomen will report around 80% to 85% AGP arousal to cross-dressing while the bisexual group will report a bit less.

But I’m also betting that in spite of that, because at least some of the androphilic group are truly androphilic, they will report less autogynephilia.  But because of the larger number of bisexual mis-reporting to be androphilic, the number will be close to that of the bisexual group, but slightly lower.  My guess, from the very slight age difference is only three or four of the seventeen are actually androphilic.  Remember, ANY difference will support the two type taxonomy as it points to the latent taxons; It just won’t be a very strong signal because of the false signal from the large percentage of bisexuals:

Sexuality:        Gynephilic                Bisexual                 Androphilic

N=                          15                              26                              17

AGP N=                  12                            14                                 7

%                            86%                         54%                            41%

Yep… this fits.  Most of those claiming to be androphilic are actually bisexual.  The researchers fell for the issue of mis-reported sexuality that is common in these studies, especially those from Europe.  The mistake is to trust self-reported attraction instead of classifying them based on actual behavior.  It is sad, because in other studies from Europe, they demonstrated just how unreliable and unidirectional the mis-reporting bias is.

Because of this, the rest of the study is nearly useless save for looking at the difference between bisexual and exclusively gynephilic transwomen’s sexual behavior.

Conclusion:  This study supports, rather than refutes, the two type taxonomy.  It shows the same pattern of autogynephilia to be found in non-exclusively androphilic transwomen.  Shows the same pattern of reduced self-report of autogynephilia in bisexually identified transwomen seen in previous studies.  And shows the same pattern of mis-reporting of sexual orientation seen in previous studies.  Yet despite that, the weak signal of exclusively androphilic transwomen NOT being autogynephilic is still detectable.  Note that even with the known mis-reporting of sexual orientation, the gynephilic transwomen are still twice as likely to report autogynephilic arousal as the self-reported androphilic.

Further Reading:

Essay exploring the Nutbrock study.

Reference:

Laube et al., “Sexual Behavior, Desire, and Psychosexual Experience in Gynephilic and Androphilic Trans Women: A Cross-Sectional Multicenter Study”, Journal of Sexual Medicine, (2020)
https://www.researchgate.net/publication/339738869_Sexual_Behavior_Desire_and_Psychosexual_Experience_in_Gynephilic_and_Androphilic_Trans_Women_A_Cross-Sectional_Multicenter_Study

2D:4D Evidence Supports Transexual Taxonomy

A new paper provided both new direct evidence and a meta-analysis of measurements of 2D:4D finger ratios in transsexuals, both FtM and MTF.  Such measurements are interesting because it is known to be influenced by testosterone levels in utero and thus an indirect measure of testosterone exposure that might influence brain sexual dimorphism.

What is doubly exciting about this paper is that the authors fully comprehend the overwhelming evidence for the two type taxonomy and of the (mild) scientific controversy regarding sexual orientation vs. age of onset as the best clinical markers for the two taxons.  The study is open access so I highly recommend following the link to it and reading it for yourself.  The study is also interesting because of where it was conducted; Iran.

Iran is a Muslim country which while being extremely homophobic, both culturally and legally, treats transsexuals fairly well, at least legally and medically.  Make no mistake, culturally, it is far from truly accepting.  Further, Iran is considered a “Collectivist Society” according to the Hofstede Individualism vs. Collectivism Index.  Lawrence has shown that this index highly correlates with the percentage of non-androphilic (and thus likely autogynephilic / late onset) transwomen transitioning in a given culture.  Thus, we would expect that there were fewer such transwomen in the study and the reported data bear this out.

Let’s look at the new data they provide:

Table 1

Means (and SD) for 2D:4D in the left and right hand for transmen, transwomen, control women, and control men

	Transmen	Control women	Transwomen	Control men
Left 2D:4D	0.991 (0.034)	0.991 (0.032)	0.981 (0.033)	0.974 (0.029)
	n = 104	n = 53	n = 88	n = 56
Right 2D:4D	0.981 (0.030)	0.983 (0.033)	0.972 (0.029)	0.959 (0.033)
	n = 104	n = 53	n = 89	n = 56

Table 2

Means (and SD) for 2D:4D in transsexuals’ left and right hand as a function of early or late onset of gender dysphoria

	Transwomen		Transmen
	Early onset	Late onset	Early onset	Late onset
Left 2D:4D	0.982 (0.034)	0.975 (0.022)	0.988 (0.033)	1.009 (0.031)
	n = 80	n = 8	n = 92	n = 12
Right 2D:4D	0.973 (0.029)	0.963 (0.026)	0.977 (0.028)	1.007 (0.027)
	n = 81	n = 8	n = 92	n = 12

Before the analysis of transfolk, it would be a good idea to scale the effect by looking at the effect size between the controls.  The difference between control women and men is d= 0.56 for the left hand and d= 0.76 for the right. This is only a moderate effect size.

Although the number of late onset is small, and thus must be viewed with caution, the analysis is still very interesting and would seem to confirm (agree) with the two type hypothesis.  Consider that the two MTF types have a small but distinct difference of d= 0.24 for the left hand and d= 0.22 for the right.  When we compare early onset type to the male controls we get d= 0.25 and d= 0.45 for the right.   When we compare early onset to female controls we get d= -0.27 for the left and d= -0.32 on the right.  This shows that early onset transwomen are roughly halfway between the controls, and if anything a bit closer to the female controls.

But even more intriguing, and the reason for trusting this interpretation is that when we compare the late onset population to the male controls we see that it exactly agrees with the hypothesis that the late onset type is essentially like the majority heterosexual male population and not at all feminized, with effect sizes that are, statistically speaking, non-existent at d= 0.04 and d= 0.12 for the left and right hands respectively.

This shows that early onset MTF type has notably hypomasculine (feminized) hands while the late onset MTF type does not, and thus in agreement with other data that supports the two type MTF taxonomy.

But what about the FtM transmen?  Here we see an even more intriguing set of data.

The two FtM types have a moderate to substantial, very notable, difference of d= -0.66 for the left hand and d = -1.07 for the right, indicating that early onset transmen are far more masculine than late onset.  When we compare the early onset FtM to female controls we find effect sizes of d= -0.09 for the left hand and d= -0.20 for the right indicating a non-existent to small masculinization signal.

However when we compare the late onset FtM to female controls we see a very different pattern with effect sizes of d= 0.57 for the left and d= 0.80 for the right.  The positive sign indicates that late onset transmen have a more feminine 2D:4D ratio than control women (!!).  And the effect size difference between early and late onset transmen is far greater than the difference between control men and women (!!!).

This, if replicated, is very big news.  It would support the notion that transmen also exhibit two taxons as has long been suspected, one that is masculinized in both behavior, sexual orientation, and very mildly in appearance, the other that is very feminine, androphilic, and autoandrophilic, the mirror image of late onset transwomen.

Further Reading:

Essay on 2D:4D History

Essay on Cultural Difference in Percentage of HSTS vs. AGP Transwomen

Essay on Androphilic Transmen

Reference:

Sadr, M., Khorashad, B.S., Talaei, A. et al. “2D:4D Suggests a Role of Prenatal Testosterone in Gender Dysphoria” Archives of Sexual Behavior (2020)
https://doi.org/10.1007/s10508-020-01630-0

Latest Trans Taxonomy Study

Wondering if the latest science studies have proven Blanchard was wrong?  Surely by now they are finding Bailey was barking up the wrong tree?  That Lawrence has been debunked?

A study published just days ago, this year, 2019 looked to test the validity of the two type taxonomy by examining forty (N=40) transwomen before and after SRS at a clinic in Germany.  European researchers have for years preferred to classify the two types as “early” vs. “late” onset of gender dysphoria.  Most have used the age of puberty as the separation line under the (false) assumption that autogynephilic sexuality does not occur in pre-adolescents.  However in this study, they chose to use the age of legal majority, 18 years old, as the dividing line.

Given that many acknowledged autogynephiles state that their first experiences with erotic cross-dressing began in adolescence, this choice of age would seem to be misplaced.  However, in using statistics, any dividing line used to cut a single population into two that shows a significant difference between two groups is useful.

Consider a dividing line that is totally random and unlikely to have any correlation with putative differences between two populations (e.g. odd or even date of birth).  If that divisor is meaningless, even if there are two different populations, that random divisor will fail to sort them and the two populations will not appear to be different when measured.  They will have the same percentages of each population.  If however, even a poor divisor that has some, albeit, imperfect correlation, the two populations will be somewhat sorted and may show statistically strong differences when measured.  That difference is enough to show that there are in fact two different populations in the larger pool.  This is what Zavlin, et Al. have found.

I would not say that this study is perfect, given that we know that the age of onset of gender dysphoria is often misreported, and the authors fully acknowledge this.  Further, the authors didn’t even attempt to collect data on autogynephilia… and chose not to analyse their data using sexual orientation as the independent variable which has been repeatedly found to provide a stronger statistical signal.  Yet, in spite of these severe weaknesses and missed opportunities, their conclusion was still,

“Our study strengthens the theory that there are 2 distinct age-related subgroups within the MtF transgender population undergoing GAS.”

Specifically, the study, in agreement with earlier studies, found that “early onset” transwomen were more likely to be exclusively androphilic than “late onset” and to transition at a significantly younger age.  Put another way, exclusively androphilic transwomen are far more likely to report having experienced an early onset of gender dysphoria than non-exclusively androphilic.  Note there are twice as many non-androphilic subjects as androphilic.

N=40     Androphilic     Non-Androphilic
Early      10 (77%)             9 (33%)
Late         3 (23%)            18 (67%)

There are also very distinctive bimodal distributions in the self-reported age of onset and of age of obtaining surgery, strongly indicative of the two type taxonomy.  This finding is in agreement with an earlier study that also found a bimodal distribution of obtaining surgery.

What I found the most interesting, in agreement with my own experience and in talking to other transwomen, is that while the “late onset” group found psychotherapy to be nearly universally useful, “early onset” transwomen did not.  Interestingly, if we compare the data carefully, it supports the notion that androphilic transwomen did not find psychotherapy useful.   I’ve commented in other essays that psychotherapists mistakenly apply what is useful for autogynephiles to androphilic transwomen to negative effect (e.g. advising a highly gender atypical androphilic transkid to seek out opportunities to privately express her “feminine side” makes no sense, risibly so…).  Here we seem to have data confirming my anecdotal observations.

The key take-away from this study is that the two type taxonomy is still very much being supported by the evidence and that those who hope that it will be proven wrong continue to be disappointed.

Further Reading:

Essay on Age of Onset vs. Sexual Orientation

Reference:

Zavlin, D. et Al., “Age-Related Differences for Male-to-Female Transgender Patients Undergoing Gender-Affirming Surgery”, Journal of Pediatric Surgery (2019)
https://doi.org/10.1016/j.esxm.2018.11.005

Once Again, With Feeling…

Or, How Do We REALLY Know That There Are Two Types of Transwomen?

One would think that with years of both clinical and scientific evidence to support the Two Type Taxonomy of MTF transexuality, we would no longer have need of essays that explain how we know this to be true, but no… sillyolme, nothing is so obvious as to be truly self-evident.  So, once again, it’s time to write a clear, concise, yet also complete explication of how we know that there are two and only two types of transwomen.

First, we need to know a bit about epidemiological research into etiology.   In medical science we often recognize that a given medical entity exists because of its pattern of symptoms that collectively we call a syndrome.  After recognizing a syndrome, science then attempts to determine an etiology, if it can.   Here it is important to recognize that the existence of a given symptom in itself does not define a syndrome.  Consider fever as a symptom.  Today, after much research, we know that it is caused by our immune system attempting to fight off an infection.  But that infection may be from any of literally millions of different entities, from eukaryotic parasites, bacteria, to viruses.  One would not say that just because two individuals both have fevers, or that a given medicine helps reduce both individual’s fevers, that they have the same etiology.  Yet, when it comes to transsexuals, this seems to be the assumption by both transexuals and the public at large.  As I will show, this is just not the case.

We also need to know a bit about statistics, most critically, about the concept of “effect size” and what it means.  Effect size is a measure of how different two populations are from one another when comparing their mean (average) and their variance (how much spread in a given measure exists within a given population).  If two populations have the same average, they have by definition an effect size between them of exactly zero, no matter the variance within the populations.  But even if they do not have the same average, if the variance in each is so large that it dwarfs the difference in average, it has a small and not very important effect size.  But if two populations have a difference in their average and no overlap in their variance, than there is a large effect size.  We calculate the effect size using a standard formula called “Cohen’s d”.

Why is this important?  Because to determine if there are in fact two (and only two) types, we must show that the Null Hypothesis, the assumption that there is only one type, is wrong by demonstrating that we consistently find that there is a large enough effect size in a number of measures that consistently cluster together.  In science we never “prove” an hypothesis… we only disprove one.  If the null hypothesis holds, there should be no such effect sizes.  So, in this essay, I’m going to review some of the evidence, demonstrating that there are respectable effect sizes and that they consistently cluster together.  Here’s the key, we DON’T have to show that that there are characteristics that give 100% vs. 0%… only that there ARE differences, respectfully large effect sizes, in order to disprove the null hypothesis.  In fact, if a study did show 100% vs. 0%, we would expect that the data was bogus, made up, given well known real world difficulties in getting perfectly truthful and accurate answers from people.

Further Reading on Effect Size

Having prefaced our discussion, let’s describe our hypothetical two types, as described by experienced clinicians:

One group  is exclusively attracted to men, transitions quite young, passed as girls/women with relative ease, were noted to be feminine (sissy boys) by parents and teachers as children, preferred female playmates, avoided rough’n’tumble play, and were unlikely to report finding wearing women’s clothing to be sexually arousing.

The other grouping was sexually attracted to women (as evidenced by extensive sexual experience with women, marriage, and siring children) but may identify as bisexual or asexual, transitioned later in life, rarely passed successfully as women, were considered to have been typical boys (“boyish”) by their parents and teachers, and were very likely to report finding wearing women’s clothes to be, or once had been, sexually arousing.

But what is the evidence and how large are the effect sizes?

Let’s look at some data.  In a study by Lawrence, conducted in 2005 among those who had had SRS by Toby Meltzer, she has three groups, those who had always been exclusively into men (androphilic), those who had always been exclusively into women (gynephilic), and those who claimed that their sexuality has switched from women to men (bisexual).

Attraction before SRS/Attraction after SRS:	F/M	F/F	M/M
Participant characteristic	(n = 30)	(n = 50)	(n = 17)
Mean age at SRS (SD)	45 (8.4)	44 (9.1)	34 (9.2)
Mean age at living full-time in female role (SD)	42 (11.3)	42 (9.6)	28 (8.8)
Very or somewhat feminine as a child, in own opinion	41%	45%	76%
Very or somewhat feminine as a child, in others’ probable opinion	21%	24%	76%
Autogynephilic arousal hundred of times or more before SRS	52%	58%	18%

.

So, let’s look at the effect size of ages at SRS and of social transition.  When we compare those who had been consistently gynephilic to those who would best be described as bisexual (having claimed sexual attraction to both men and women) we see that Cohen’s d for age of SRS is only 0.11, so tiny as to be essentially zero.  For age of social transition Cohen’s d is 0.0000 = zero.  Thus, we would have to say, for this characteristic and these two populations the null hypothesis is not disproven.  Again, this does not mean that the null hypothesis is proven… only that it is not disproven.  Gynephilic and bisexual transwomen could be the same underlying etiology… or not.

Oh… but let’s look at the androphilic group compared to these other two groups, shall we?  Comparing age of SRS between the bisexual and androphilic Cohen’s d = 1.25, a very large effect size.  Comparing their ages of social transition Cohen’s d = 1.48, also a very large difference.  Finally, looking at the ages of SRS and ages of social transition between the gynephilic and androphilic groups Cohen’s d = 1.09 and 1.44 respectively.  This very powerfully disproves the null hypothesis.  Sexual orientation is definitely important and supports the two type hypothesis.

Lest you think this result is from only one study, consider the even larger Nuttbrock study in which we see that of those who have started HRT, fully one half of the exclusively androphilic had done so before they turned age 20, while only one exclusively gynephilic individual had done so.

Our description of the two types also mentioned other characteristics, such as gender atypicality and autogynephilia.  Now here, we have a small problem in that we don’t have measures that have a continuous value nor a variance.  These were bivalued.  However, interestingly, because people don’t always answer perfectly, we can use the number of people who answer a given way as a pseudo continuous measure of the real continuous value.  That is to say, if only a small number say yes to a question, it’s likely that the real value is very small.  If a large number answer yes to a question, it’s likely that the real value is very large.  So, let’s look at the values for self image and likely impression to others of being gender atypical.  Oh look, consistent with our earlier conclusion that the gynephilic and bisexual groups were in fact not really different groups, their answers are very similar at 41% vs. 45% and 21% vs. 24%.  These are so close, that we might as well agree that they are identical.  And once again, we see that the androphilic group scores are quite different at 76%.  Notice something very interesting, the androphilic group scores for the two questions are identical, but the gynephilic and the bisexual both have the same difference, strongly supporting the null hypothesis that gynephilic and bisexual are not different.  So, consistent with our earlier conclusion, the null hypothesis that there is only one group is very much disproven while the hypothesis that there are two and only two is strongly supported.

Before we leave Lawrence’s study, lets look at the issue of autogynephilia.  Again, we have a bivalued question whether one had experienced hundreds (or more) episodes of autogynephilic arousal to wearing women’s clothing.  As before, we see that the gynephilic and bisexual groups are very similar at 52% vs. 58%, while the androphilic group had only 18%.  So, once again, consistent with our earlier conclusion, the null hypothesis that there is only one group is very very much disproven and the hypothesis that there are two and only two is supported.

Associations between autogynephilia and sexual orientation
in MtF transsexuals and transgender persons

---

%AGP: Gynephilic (includes bisexual and asexual) vs. Androphilic

Study		Gynephilic AGP		Gynephilic NonAGP		Androphilic AGP		Androphilic NonAGP
Blanchard (1985)		46		17		15		85		75% vs. 15%
Blanchard et al. (1987)		60		13		5		47		82% vs. 10%
Lawrence (2005)		178		21		6		9		89% vs. 40%
Smith et al. (2005)		28		16		18		40		64% vs. 31%
Nuttbrock et al. (2011)		131		48		90		301		82% vs. 23%
TOTALS		443		115		134		482		79% vs. 22%

---

Note: The four center columns display numbers of participants

Again, lest you think this result is restricted to only this study, we have seen this replicated by Buhrich (1977), Freund (1982), Blanchard (1985), Doorn (1994), Smith (2005), and Nuttbrock (2011), Laube (2020), in separate studies spanning five decades, collectively involving over a thousand transsexuals to date.  In fact, this is one of the most repeated and reconfirmed scientific finding regarding transsexuality.

Another characteristic difference mentioned about the two types was passability.  Fortunately, we have a clinical study from the Netherlands which showed a robust effect size d = 0.7 difference between androphilic and non-androphilic transwomen.  The graph above shows the data.  The higher the score, the more ‘readable’ (less passable) the individual.  From the graph, we see that the most passable non-androphilic (gynephilic and bisexual) is just average for the androphilic population.

When we add in the growing evidence that there is a distinct difference between the brains of androphilic vs. gynephilic & bisexual, the null hypothesis that there is only one type is not just merely dead, but most sincerely dead.

Addendum 1/15/2018:

Study after study has shown that around 80% to 85% of “non-homosexual” transwomen readily acknowledge experiencing sexual arousal to cross-dressing, at least in adolescence, while they also show that around 50% acknowledge continuing arousal.  This leaves 15% or so who say that they never experienced sexual arousal to cross-dressing.  As we’ve seen, social desirability bias is strongly operating.  At least some percentage of the population is not being honest.  Interestingly, there is a new study exploring the subject of honesty and dishonesty.  It was discovered that there are three types of people that I shall paraphrase as “always honest”, “mostly honest”, and the “never honest”.

Guess what the percentages were?

“always honest” = 50%
“mostly honest” = 35%
“never honest” = 15%.

Wow, what an interesting coincidence.

Many transwomen who are critical of the two type taxonomy have specifically called out Blanchard and any who accept and advocate the taxonomy as being ugly transphobes for having called transwomen liars.  But are we to suppose that transwomen as a population are somehow more saintly and honest than the general population?  Phhfft !

https://www.technologyreview.com/s/609924/a-field-guide-to-deception/

 

Further Reading:

Essay on Lawrence Study

Essays on Evidence Supporting the Two Type Taxonomy

Essays on Brain Sex

Brainstorm

A new review paper has just been published on the current status of brain structure research in transsexuality.  Interestingly, it was submitted to the Archives of Sexual Behavior two full years ago.  This suggests that it went through a rather thorough peer review.  For myself, the first thing I do when reading a review paper is to see that the reference list is comprehensive to ensure that the authors aren’t cherry-picking.  In this case, they are not.  The paper looks to be very complete and scientifically honest.  You may wish to read it yourself, as it is not behind a paywall, thankfully.

The paper is written rather densely, with a great deal of information and discussion; so much in fact, that I will likely be writing several essays covering a number of topics from it.  At the high level, my regular readers will not be surprised at the primary conclusions drawn from the review, as I had already written about a fair number of the brain research papers.  The authors offer this chief conclusion at the end of the paper,

“The review of the available data seems to support two existing hypotheses: (1) a brain-restricted intersexuality in homosexual MtFs and FtMs and (2) Blanchard’s insight on the existence of two brain phenotypes that differentiate “homosexual” and “nonhomosexual” MtFs”

The review of all of the available brain structure research fully supports the Two Type Taxonomy.  In light of this, the authors recommend that future researchers take care to distinguish between the two types, lamenting that some studies in the review had not made this distinction, and further, that it is important that the control groups also be concordant with sexual orientation,

“The study of mixed samples implicitly assumes that transsexuals are a homogeneous group. This is far from the truth with respect to the onset of GD and sexual orientation.  …  These observations signify that control groups in studies of the transsexual brain must be homogeneous in regards to sexual orientation.”

The authors did find separate studies of androphilic “homosexual” MTFs and non-gender dysphoric gay men that used the same methods, such that a tentative comparison could be made,

“The only study on the CTh [cortical thickness] of homosexual persons that do not present gender dysphoria is by the Savic group (Abé et al.). If we compare this study with that of Zubiaurre-Elorza et al. on the CTh of homosexual MtFs, we see both studies report sex differences showing an F > M pattern in similar structures of the right hemisphere. But there is only one region, the pars triangularis, in which homosexuals and homosexual MtFs both present differences. However, these changes are in opposite directions. The pars triangularis of homosexual MtFs is thicker than in heterosexual male controls, while for homosexuals it is thinner than in heterosexual males. Thus, it seems that for transsexuals this region is feminized but demasculinized [i.e.: “different that straight men, but not in the heterosexual female direction” – K. Brown] in homosexual individuals. Interestingly, in both studies, the affected pars triangularis is in the right hemisphere. Nevertheless, confirming Blanchard’s prediction still needs a specifically designed comparison of homosexual MtF, homosexual male, and heterosexual male and female people.”

This is interesting, that there is a difference between gay men and androphilic transwomen?  But the right hemisphere pars triangularis of all things?  For left hemisphere dominant people, this region of the brain is believed to be involved in the understanding and production of prosody, emotionally nuanced speech modulation.  We know this because individuals who have serious lesions in this area have trouble with prosody.

For more information, read the Wikipedia page on prosody.

Before anyone gets too excited about the possible implications for a neurological marker for androphilic transsexuality that differentiates them from gay men, we need to note that the brain exhibits neuroplasticity.  That is to say, that like a muscle, exercise of particular skills causes the brain to increase in volume and neuron number in those regions used to supply that skill.  If this is about language and more particularly, about language production that imparts an emotional / sexual identity / gender identity through one’s voice, the difference in this part of the brain may be caused by experience and practice.

For more information, read my essays on feminine speech production and on voice recognition.

On the other hand, it just might represent a real difference.  We need more studies.

References:

Guillamon, A et al., “A Review of the Status of Brain Structure Research in Transsexualism” Arch Sex Behav (2016). doi:10.1007/s10508-016-0768-5

 

Brain Power…

“…I would while away the hours, confir’in with the flowers…. if I only had a brain…”  — Scarecrow, in the Wizard of Oz musical film.

After years of trying to explain the differences between the two types and the statistical evidence for the two type taxonomy of MTF transwomen, I’m now posting what should be the final clincher; solid biomedical laboratory evidence, “proof” even.

Decades ago, as I was researching our collective history and science (the two often go hand in hand), I came across a reference to studies that showed that gay men had feminized brains while MTF transsexuals did not.  SAY WHAT!?!?

Turns out, the study referenced made the false assumption that all MTF transsexuals are the same and had only included gynephilic older transitioners.  Other studies, being aware of, and accounting for the differences between the two MTF transsexual types found something quite interesting, as for example, from the Dörner (1983) abstract:

“In male rats, androgen deficiency during a critical period of sexual brain differentiation was shown to give rise to a predominantly female-differentiated brain. Such animals displayed “homosexual behaviour”, i.e., they were sexually attracted preferentially to partners of the same sex. In addition, they exhibited a sex-specific evocability of a positive oestrogen feedback effect. A positive oestrogen feedback effect on LH secretion was also induced in homosexual transsexual men, in contrast to hetero- or bisexual transsexual men. Thus in homosexual transsexual men, an intravenous injection of 20 mg Presomen (Premarin) produced a significant decrease of serum LH levels followed by a significant increase above the initial LH values. In hetero- or bisexual transsexual men, by contrast, intravenous oestrogen administration, while producing a significant decrease of serum LH levels, was not followed by an increase above the initial LH values. A positive oestrogen feedback effect on LH secretion was also found in homosexual non-transsexual men, in contrast to heterosexual men. These findings suggest that transsexual as well as non-transsexual homosexual men possess a predominantly female-differentiated brain which may be based, at least in part, on androgen deficiency during sexual differentiation of the central nervous system. Homosexual transsexual men also showed an increased LH and FSH response to LH-RH as compared to hetero- or bisexual transsexual men.”

Note that non-exclusively-androphilic (“heterosexual or bisexual”) transwomen did NOT have the female like positive estrogen feedback effect on LH serum levels.  Of course, according the Blanchard’s work, all “non-homosexual” MTF transsexuals should also be in the same taxon, so we would predict that so-called, asexual transsexuals should also show the lack of this positive feedback, and indeed, this too was found, as discribed in the Dörner’s (1976) earlier paper,

“In transsexual men with homosexual behaviour and intact testicular function, as well as in homosexual men with normal gender identity, following a negative oestrogen feedback effect a delayed positive oestrogen feedback action on LH secretion was evoked. By contrast, in transsexual men with hypo- or asexuality and intact testes or hypergonadotrophic hypo- or agonadism, as well as in heterosexual men with normal gender identity, a negative oestrogen feedback effect was not followed by a positive feedback action on LH release. In transsexual women with homosexual behaviour and oligo- and/or hypomenorrhoea, only a weak or at best moderate positive oestrogen feedback action on LH release was evocable, similarly as in castrated and oestrogen-primed heterosexual men. By contrast, in a transsexual woman with bisexual behaviour and eumenorrhoea, a strong positive oestrogen feedback action on LH secretion was evocable, as well as in heterosexual women with normal gender identity.”

Note that in this paper we see a mirror like difference between FtM “homosexual transsexuals” (gynephilic transmen) who respond more like heterosexual men and bisexual FtM transmen who respond more like heterosexual women.  Thus, this data would lend support for there being a taxonic difference between exclusively gynephilic and non-exclusively gynephilic transmen, mirroring the taxonic difference between the two types of transwomen.

Conclusion:

These papers, detailing a specific, repeatable, laboratory based test that can differentiate the two types of transsexuals described by Blanchard, “Homosexual” and “Non-Homosexual”, offers both supporting evidence for the two type taxonomy but potentially also a way of independently sorting the two types in future studies.  This difference is a classic medical biomarker for the two types.  Should anyone one doubt the weight of statistical evidence, we can also point to the biomedical evidence via laboratory tests.

Addendum 9/2/2017:

In exploring science, it is important not to cherry pick or ignore papers which fail to support a given hypothesis.  So, I am adding another paper to the list of reference and discussing a paper that on the surface would seem to be contradict Dörner’s results.  Unfortunately, these papers are behind paywalls and I don’t have copies of them… so I clearly don’t have the details… only the abstracts.  Gooren reported in two papers attempts to replicate the LH response and found mixed results, from the ’86 abstract,

“The neuroendocrine response of LH to estrogen administration may be related to sexual dimorphism of the brain, and therefore, homosexual and especially transsexual individuals may differ from heterosexual individuals in their responses. This study failed to find such differences among groups of female heterosexuals, homosexuals, and transsexuals. Specifically, after single dose estrogen administration, all subjects had an initial decline in serum LH levels, followed by a brisk rise of equal magnitude. Among males, the type of response was less uniform. After an initial fall in serum LH levels, the individual responses varied. In 12 of 23 male homosexuals, 10 of 15 male heterosexuals, and all 6 genetic male transsexuals studied, serum LH levels remained below pretreatment levels. In the remaining 11 male homosexuals and 5 of the heterosexuals, serum LH levels increased to values exceeding those before treatment, resembling the response found in the 3 groups of women. Those homosexual and heterosexual men with a rise in serum LH levels to above pretreatment values also had the greatest fall in testosterone levels after estrogen administration, while these same men had the lowest testosterone response to hCG stimulation. I conclude from these results that 1) the similarity of LH responses to estrogen administration in all groups of women studied does not support a theory of brain androgenization as a factor in the establishment of gender identity of sexual orientation; and 2) individual differences in men in the type of LH response to estrogen administration can be satisfactorily explained by endocrine factors, such as Leydig cell function, and need not be related to gender identity, sexual orientation, or other possible causes.”

And in an early ’84 paper,

“In order to test the hypothesis whether there is variation in hormonal levels or response to hormonal manipulation that could permit a distinction between heterosexuals and transsexuals, we designed the following protocol: Six male-to-female (m-to-f) transsexuals, six heterosexual control females and six female-to-male (f-to-m) transsexuals were given estradiol benzoate (E2B) (4.5 micrograms/kg/12 hr) for five days. In the female population, E2B treatment was initiated on day 5 of the menstrual cycle. In all the subjects blood luteinizing hormone (LH) and follicle stimulating hormone (FSH), estradiol-17 beta (E2) and testosterone (T) levels were measured twice daily. Additionally, LH and FSH responses to LHRH (100 micrograms iv) stimulation prior to and on day 5 of the E2B treatment were evaluated. In the m-to-f transsexuals, T levels decreased sharply and progressively during estrogen treatment, along with a fall in LH and FSH levels. The magnitude of the LH and FSH responses to LHRH stimulation also decreased following estrogen administration. In the heterosexual female controls and in the f-to-m transsexuals, estrogen administration increased LH levels to a minimum of 100% above initial values from day 3 onwards.  There was no convincing evidence for the existence of a positive estrogen feedback on LH secretion in m-to-f transsexuals. These results contradict some of the reported hypotheses concerning hormonal alterations in these individuals.”

However, in both studies, Gooren made no effort to differentiate between exclusively androphilic (homosexual) transsexuals and gynephilic/bisexual MTF transsexuals as Dörner did.  Given the copious evidence from statistical and brain morphology research that differentiates the two types of transwomen, this limits the utility of Gooren’s studies.  The only true dissonance between the studies is that Gooren found only a slight difference between homosexual and heterosexual (non-trans) men: 52% of homosexual and 33% of heterosexual men showing a positive LH feedback, while all 6 of the MTF transwomen failed to show any such positive LH feedback.

Although it would appear that this fails to replicate Dörner, I’m astounded that all six of the transwomen failed to show any LH feedback when at least some of the non-transfolk, both homosexual and heterosexual did so.  Without knowing which type of transsexual these subjects are, we can’t really say that this fails to replicate Dörner.  They could all be gynephilic.  There does seem to be small effect size between gay and straight men, but the sample sizes are all too small.  Further, I would be very curious as to how Dörner and especially Gooren determined the sexual orientation of their subjects and whether they were exclusively heterosexual and homosexual.

Interesting that all of the FTM transmen showed an exaggerated LH feedback, hmmmm…

Given the Gooren data, small sample as it is, perhaps adding to it another study regarding the difference between heterosexual and homosexual men?  We have such a study in Gladue, from the abstract,

“A neuroendocrine component, the positive estrogen feedback effect, thought to be related to sexual orientation and, indirectly, to sexual differentiation, was evaluated in healthy, noninstitutionalized research volunteers. Men and women with a lifelong heterosexual orientation and men with a lifelong homosexual orientation were administered an estrogen preparation known to enhance the concentration of luteinizing hormone in women but not in men. The secretory pattern of luteinizing hormone in the homosexuals in response to estrogen was intermediate between that of the heterosexual men and that of the women. Furthermore, testosterone was depressed for a significantly longer period in the homosexual men than in the heterosexual men. These findings suggest that biological markers for sexual orientation may exist.”

Although, to be fair, this study was also small, but when we add them all together, the direction of the effect seems to be real.

References:

Dörner G, Rohde W, Schott G, Schnabl C., “On the LH response to oestrogen and LH-RH in transsexual men.” Experimental Clinical Endrocrinology (1983)
http://www.ncbi.nlm.nih.gov/pubmed/6317420

Dörner G., “Neuroendocrine response to estrogen and brain differentiation in heterosexuals, homosexuals, and transsexuals.” Archives of Sexual Behavior (1988)
http://www.ncbi.nlm.nih.gov/pubmed/3282489?dopt=Abstract

Dörner G, Rohde W, Seidel K, Haas W, Schott GS.”On the evocability of a positive oestrogen feedback action on LH secretion in transsexual men and women.” Endokrinology (1976)
http://www.ncbi.nlm.nih.gov/pubmed/1244197

Gooren L. et al., “Estrogen positive feedback on LH secretion in transsexuality.” Psychoneuroendocrinology (1984)
https://www.ncbi.nlm.nih.gov/pubmed/6436856

Gooren L., “The neuroendocrine response of luteinizing hormone to estrogen administration in heterosexual, homosexual, and transsexual subjects.” Journal of Clinical Endocrinology and Metabolism (1986)
https://www.ncbi.nlm.nih.gov/pubmed/3016021

Gladue A., Green R. Hellman R., “Neuroendocrine response to estrogen and sexual orientation” Science (1984)
https://www.researchgate.net/publication/17097653_Neuroendocrine_response_to_estrogen_and_sexual_orientation

 

Shades of Grey…

Shades of Grey… Matter

We live in exciting times – At least scientifically.  We can now peer into the heads of transsexuals to see if their brains exhibit sexually dimorphic features that match their natal sex or their preferred gender.  Years ago, Ray Blanchard made a prediction, based on early evidence that there was a taxonic difference between “homosexual” and “non-homosexual” transwomen in sexuality, natural gendered mannerisms, age of transition, etc, that the former would show sexually dimorphic features in the brain that were shifted in the female direction while the latter would not, but would show features that were different than controls, but that they would not be sexually dimorphic features, and definitely not shifted in the female direction.  We now have yet more evidence that that prediction is correct, giving more weight to the two type taxonomy of MTF transsexuality, namely exclusively androphilic vs. autogynephilic.

The best evidence would be to use two populations of transwomen, one known to be exclusively androphilic and the other not, and test them for the same features, using the same type of measurement.  We now have that data for grey matter distribution in the brains of both types of transsexual.

In the earlier Savic and Arver paper, they compared grey matter distribution of 24 gynephilic transwomen, before HRT to that of heterosexual men and women.  (Remember, HRT itself causes a shift in sexually dimorphic features due to activational effects of sex hormones, and the lack of such hormones.)  The conclusion?

“The present data do not support the notion that brains of (gynephilic) MtF-TR are feminized.”

In the later Simon paper, they compared grey matter distribution of 10 exclusively androphilic transwomen, and 7 exclusively gynephilic FtM transmen, before HRT to that of heterosexual men and women.  The conclusion?

“Our findings support the notion that structural differences exist between subjects with GID and controls from the same biological gender. We found that transsexual subjects did not differ significantly from controls sharing their gender identity but were different from those sharing their biological gender in their regional GM volume of several brain areas, including the left and right precentral gyri, the left postcentral gyrus (including the somatosensory cortex and the primary motor cortex), the left posterior cingulate, precueneus and calcarinus, the right cuneus, the right fusiform, lingual, middle and inferior occipital, and inferior temporal gyri. Additionaly, we also found areas in the cerebellum and in the left angular gyrus and left inferior parietal lobule that showed significant structural difference between transgender subjects and controls, independent from their biological gender.”

The choice to explore only “homosexual” transsexuals in this study was informed by the researchers’ knowledge of the Freund/Blanchard taxonomy and of Blanchard’s prediction, as they explained,

“Both MTF and FTM patients were eligible for the study, but only those with homosexual orientation. The rationale for this choice was based on the Blanchard typology which considers two fundamentally different types of transsexualism: homosexual and nonhomosexual. Homosexual transsexual individuals are sexually attracted to the same biological gender, while nonhomosexual transsexual individuals are attracted to either the opposite gender or show no sexual orientation/attraction at all. According to Blanchard, homosexual transsexuals are usually younger at initial presentation of gender identity disorder and show more pronounced and frequent childhood femininity, as well as different anthropometric data. One might argue that mixing individuals from both transsexual groups in one study targeting the neurobiological background of transsexualism might bias the results by introducing heterogeneity in the sample. Thus, in our study, only homosexual transsexual individuals were included preventing our findings from the aforementioned bias.”

This points to growing recognition within the scientific community that the two type taxonomy is correct.  They went further, indirectly referring to the taxonomy and Blanchard’s prediction,

“In another study also limited to MTF transsexuals Savic and Arver, reported no “feminization” of any brain region with regard to structure. Nonetheless, certain brain areas (clusters ≥100 voxels) showed characteristic structural features in the transsexual group compared with both male and female control groups. Specifically, they found reduced thalamus and putamen volumes and increased GM volumes in the insular and inferior frontal cortex and in the right temporo-parietal junction (angular gyrus and superior temporal gyrus) in the transsexual group compared with both control groups. In our study, however only the angular gyrus (but in the left hemisphere) was affected among these areas, showing lower regional GM concentration in both FTM and MTF transgender subjects compared to controls, independent of their biological gender. When comparing the results reported by Savic and Arver to either our study or to other imaging studies in the literature of transsexualism, it has to be taken into consideration that their reported results were obtained from a solely nonhomosexual transsexual group of patients. The lack of real overlap between our and Savic and Arvers’ findings, despite the very similar methodology used, might at least in part be explained by the difference of the sexual orientation of the two samples.”

Truly, exiting times.

References:

Ivanka Savic, Stefan Arver, “Sex Dimorphism of the Brain in Male-to-Female Transsexuals”
http://cercor.oxfordjournals.org/content/early/2011/04/05/cercor.bhr032

Lajos Simon, Lajos R. Kozák, Viktória Simon, Pál Czobor, Zsolt Unoka, Ádám Szabó, Gábor Csukly, “Regional Grey Matter Structure Differences between Transsexuals and Healthy Controls—A Voxel Based Morphometry Study”
10.1371/journal.pone.0083947

 

Autistic Sky

For the past several years, evidence has been accumulating that there is a fairly high comorbitity between transsexuality / transgenderism and the autism spectrum.  Interestingly, and perhaps not totally surprisingly, among MTF transwomen, it appears to be exclusively found in the non-exclusively androphilic population.  This fits the Freund/Blanchard taxonomy and more importantly, Blanchard’s prediction that “non-homosexual” (with respect to natal sex) MTF transwomen would exhibit neurological / brain differences from control males but these differences would NOT be a shift toward female like brains.

Autism and autism spectrum disorders are found in four to five  times as many men as women.  There are a number of theories as to why this happens, including the rather intriguing “hypermasculine brain hypothesis”, in which a link between the slight differences between men and women, as groups, having different cognitive and social behaviors and the apparent similarity, or rather, exaggeration of these differences between men and women, found in those on the autism spectrum.  If autism is a form of hypermasculinization, it would not surprise us to learn that FTM transmen were more autistic-like than most women… and that is what one group of researchers found.

Using a 50 item, Likert scored, instrument called the Autism Spectrum Quotient (AQ), Jones, et Al., found that FTM transmen as a group, scored 23.2, higher than control women AND men!  This puts about half of the FTM onto the high functioning autism spectrum!!   (The lower AQ cut-off for ASD is 23.)  Non-exclusively-androphilic transwomen scored essentially the same as the control men, while exclusively androphilic transwomen scored essentially the same as the control women, and definitely (statistically significant: p<0.03 ) below both the control men and non-androphilic transwomen.

Group:               Men                  Women       FTM                 Non-Androphilic           Androphilic
.                                                                                                     MTF  N=129                   MTF N=69

Score (SD):       17.8 (6.8)        15.4 (5.7)     23.2 (9.1)        17.4 (7.4)                         15.0 (5.6)

The implication is clear, FTM’s are masculine, perhaps even hypermasculine, while the data also supports the Freund/Blanchard two type taxonomy for MTF transwomen.  In the discussion section of the paper, the authors remarked,

“Interestingly, with the 198 transwomen group, there were 6 individuals (i.e. 3%) with a diagnosis of AS. This rate is about 3 times as many as in the general population.”

These authors didn’t state what the sexuality of the six AS individuals were; but if they conform to the greater likelihood that they were non-androphilic, found in other papers, the incidence rate for such non-androphilic transwomen would be closer to five times the rate found in the general population, however, that is only about twice as high as that found in the male population.

(Addendum: 1/21/2017:  Looking at the data again, this time from the perspective of effect sizes with respect to men vs. women and non-androphilic vs. androphilic aids us in understanding how important this difference is.  First, the effect size between men and women is 0.38 a modest but still very noticable difference in the populations.  Now, let’s look at the diffence between non-androphilic and androphilic at 0.37, nearly identical to the difference between men and women.  So, lets compare the difference between men and non-androphilic tranwomen at 0.06 which is tiny.  And similarly, when we compare between women and androphilic transwomen it is only 0.07 which again is very tiny.  That is to say, these statistical tests shows that the difference between men and women is the same size as between non-androphilic and androphilic transwomen, while there is effectly no difference between men & non-androphilic and women & androphilic transwomen respectively.  That is to say, that non-androphilic transwomen are identical to men in general, while androphilic transwomen are essentially the same as women in general.  Further the difference between the two types of transwomen exactly matches the difference between men and women, which strongly supports the Two Type Taxonomy.)

Further Reading:

Autism and Transgender

References:

Jones, et Al, “Female-To-Male Transsexual People and Autistic Traits”, J. Autism Dev. Discord. DOI: 10.1007/s10803-011-1227-8

Annelou L. C. de Vries, Ilse L. J. Noens, Peggy T. Cohen-Kettenis, Ina A. van Berckelaer-Onnes. Theo A. Doreleijers, “Autism Spectrum Disorders in Gender Dysphoric Children and Adolescents” Journal of Autism and Developmental Disorders (2010)
https://link.springer.com/article/10.1007/s10803-010-0935-9