Oct 112013
fMRI image from the study

fMRI image from the study

This study was a two-part study. They compared trans and cis participants while viewing erotic vs nonerotic videos and then responding to questionnaires. They also did fMRI brain scans on the participants. Researchers concluded that trans participants had a stronger anterior cingulate cortex to ventral tegmental area connection than cis participants. However, this study was problematic, as you’ll see further down, and I do not think its results can be taken without a very large grain of salt.

Unusual among trans studies, this study came out of China. 41 trans folk were recruited for the study, 21 trans men and 20 trans women. Trans people both on hormones and not on hormones were included, but no participants had had surgery. All trans participants were recruited from a psychiatric clinic. The control group was 38 heterosexuals recruited from the internet, equally split between sexes. For the brain scan study, only trans participants who were not on hormone therapy were involved to reduce the possible variable of sex hormones. Participants were screened for pregnancy, ovulation, a history of sexual abuse, consumption of certain substances or within 24 hours of the study (alcohol, caffeine).

Participants were also screened for their sexual orientation. The control group was only “heterosexual”, the trans group mostly “homosexual”. Why the quotes? Well in truth, their categorizations ignored bisexuals. The way they coded participants, a cis person who preferred (but not exclusively preferred) the same sex to the opposite sex would be classified as “homosexual”. The authors do not clarify what they mean by a “homosexual” trans person. Historically, the label “homosexual” in reference to trans people refers to their sex, not their gender. It’s considered offensive to use that terminology today. A trans woman who was attracted to men would be considered homosexual. Because the authors didn’t define “homosexual” in the context of trans people, I have no idea what they actually meant. I can only assume they meant that old, disrespectful meaning. That is, that all the trans women in this study were attracted to men and all the trans men in this study were attracted to women.

Participants watched 8 short films: 4 heterosexual erotic films and 4 heterosexual non-erotic films. After watching the films, they were asked to rate how aroused they were after the film and asked how much they identified as male/female during the film. Participants also filled out other questionnaires including:

  • Questions assessing how much the participant identified as the opposite sex, and how much the participant desired to be the opposite sex
  • the Beck Depression Inventory, a well-established measure of depression and suicidality
  • the Defense Style Questionnaire, an assessment of which Freudian defense mechanism one uses
  • the Klein Sexual Orientation Grid, as described above.

Results for this part of the study? Well, all participants were aroused by the erotic films. All groups identified statistically significantly more with their gender than their sex for all films. No difference was found between trans people on or not on hormones. As for the questionnaires…? Well the authors don’t actually talk about them in the results section – you have to go back up to demographics to find it…. And no surprise, trans people were significantly more likely to identify as the opposite sex, desire to be the opposite sex, and have more depression symptoms than their cis counterparts. Trans people were also significantly more likely to use the defense strategies of “undoing“, “altruism“, and “displacement“.

But what about the brain scans? Let’s look at those next… A subgroup of control participants, and all the trans participants who were not on hormones, participated in this part. fMRI was used while participants rests, staring at a specific point on a wall. fMRI is a technique which images changes in blood flow in the brain.

The researchers examined the connection between two specific areas of the brain: the ventral tegmental area and the anterior cingulate cortex. Why those parts? I’ll let the researchers speak for themselves. They describe the anterior cingulate cortex as “a neural structure central to the consciousness of self and conflict monitoring as well as social processing”. They describe the ventral tegmental area as “a neural substrate that is involved in dimorphic genital representation and the rewarding value of sexual behaviors.”

From what I can tell, from my memories of my neuroscience class, my neuroscience textbook, and the internets, I think they’re overstating the known roles of those brain areas. The anterior cingulate cortex does seem to have a role in detecting errors and cognitive and emotional self-regulation. However, it’s a far cry from that to declaring that it’s “central to the consciousness of self.” I have no idea what the authors mean by the ventral tegmental area being involved in “dimorphic genital representation”, since their citations have nothing to do with that. Their citations for that claim are two papers showing that blood flow increases in the ventral tegmental area during both cis male and cis female orgasm. That’s not exactly a surprise – the ventral tegmental area has to do with reward processing and is known to be involved in addiction. But “dimorphic genital representation”? Not a clue. That phrase doesn’t seem to exist anywhere outside their paper.

The authors state that they found more connectivity between the ventral tegmental area and the anterior cingulate cortex in their trans participants than in their control group. I don’t have enough background in interpreting fMRIs to evaluate that claim. If someone out there reading this does, your input would be welcome!

The authors do not discuss their results. The only “discussion” I found was in their abstract, where they conclude: “The neural connectivity pattern suggests a brain signature of the psychosocial distress for the gender-sex incongruity of [trans people]”. …maybe? But that sounds like a big assumption to me. There are just too many variables for that conclusion to be reasonable. An enhanced connection between the anterior cingulate cortex and the ventral tegmental area could easily be explained as a general reaction to psychosocial stress, not necessarily gender dysphoria. In fact, that appears to be a more reasonable hypothesis, given some recent studies which I found on a quick trip through Google.

I find this study highly problematic. I do not think their conclusions are supported by the data they present. Nor do I think their methods were sound, nor their participant selection. Specific problem areas I saw in addition to the ones I already mentioned include:

  • The study is insufficiently justified. Why exactly was it done?
  • The methods are insufficiently justified. My first thought when I saw it involved erotic vs nonerotic videos was that the researchers were conflating sexual orientation and gender identity (again). I don’t see anything in the paper that dissuades me from that first impression.
  • Participants were pulled from completely different pools. All trans participants were from a psychiatric clinic and all cis participants from an online forum. They are not comparable! And I have some serious ethical concerns with using trans participants specifically from a psychiatric clinic. There may have been subtle psychological and sociological forces at work which induced them to participate, despite the reassurances of the researchers that participation would not affect their treatment (hormones). It reminds me of an old study of Blanchard’s from the 1980’s where cross-dressers in a psych unit who were not financially compensated were compared to a control group who was not in a psych unit and who were financially compensated.
  • The Defense Style Questionnaire sounds very Freudian to me. Considering that the vast majority of Freud’s theories are not considered scientific (being unmeasurable), its inclusion seems fishy to me.
  • Trans participants were statistically significantly more likely to have more depressions symptoms on the Beck Depression Inventory, yet the authors did not consider this in their conclusions. It seems to me to be a huge confound. It would be much better to compare trans participants with a cis group with a similar score.

In summary, I do not think this study adds very much to our knowledge of trans brains. But I very much would like to hear what everyone else thinks of this study. Does it make sense to you? Did I miss something you see? Please do let me know! 🙂

This paper is publicly available in its entirety at PLOS ONE.

  3 Responses to “Article Review: Brain Signature Characterizing the Body-Brain-Mind Axis of Transsexuals”

  1. […] yet these studies in large part seem to be inconclusive, and in many cases demonstrate a questionable amount of bias. Though these studies have the potential of validating the transgender experience by providing […]

  2. I’d like to know what the end purpose is. I hope that it is to find out about brain differences alone, not about finding a way to further qualify trans* people.
    Specifically, I mean this. If we find out that there is some particular -thing- in people’s brains that indicates their gender identities, do we diagnose people as trans* regardless of their identities? If we find out that there is not such a -thing-, do we discount all people’s identities altogether?

    I’m also a little confused about the necessity of sexuality in this study, since sexuality has nothing to do with gender identity at all…

    • There are a number of reasons to investigate brain differences between cis and trans folk. There’s the eternal curiosity of science. There’s the argument that transgender is a medical condition, and thus transition is warranted, psychotherapy will not help, and all medical treatment should be covered by insurance – evidence such as that in these studies is useful for that argument!

      I’m doubtful that we’ll get to the point anytime soon where a living person could be diagnosed trans from brain scans. And like you, I have my reservations.

      Historically speaking, minority sexuality and gender identity have tended to be mixed. There’s still confusion prevalent not only in the general Western culture but in research as well.

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