White matter

Transsexual people exhibit different brain structure. A team at the National University of Distance Education, Madrid, performed MRI scans on 24 males, 19 females and 18 female to male trans folk, who had had no treatment. They found significant differences between male and female brains in four regions of white matter, and the trans men had white matter in those regions resembling a male brain. The team made a separate study of 18 trans women, finding that the structure of the white matter was half way between that of the males and females.

Words like “superior longitudinal fascicle” may trip off my tongue as easily as base-nodule of the stria terminalis central section. It may have implications on body perception.

In 2011, the New Scientist (where I found this) suggested that trans-identifying children with such white matter anomalies could benefit from treatment to delay puberty, but no such work had yet been done. The New Scientist referred to Sean Deoni’s work on white matter development in infants, but publication considered a causal link between breast feeding and improved intelligence, previously demonstrated epidemiologically. Here is the 2011 Journal of Psychiatric Research article, on the Spanish research.

As soon as April 2011, Neil Whitehead opined that any brain differences were caused by “years of repetitive thinking, fantasy and preoccupation with body image”. Reading the NS report, “each” M-F had the brain differences, and “the female to male transsexual people had white matter in those regions which resembled a male brain”, but Whitehead says “a modest majority had brains more like their heterosexual female counterparts”. This could be evidence of lying, though the two reports could be choosing different aspects to emphasise.

Whitehead’s is a prejudiced site: its home page states that “Huge amounts of impartial scientific evidence now make it abundantly clear that homosexuality is not biologically hard-wired and that change is possible”. This is a minority view.

This is all of limited use in deciding whether to transition. The question is, will you be happier transitioned? How much do you want it, and how accepting is your society? It has some use in persuading the undecided, though people like Whitehead will oppose it. More persuasive is the fact that people want to transition. Why not just let us?

More long words: White matter microstructure diffusivity.