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2014-11-15 Brains of female transsexuals have female features; birth order suggests a causal biological mechanism

posted 15 Nov 2014, 06:25 by Cake Kidd   [ updated 15 Nov 2014, 06:26 ]

Heya everybody,

I managed to add another 25 studies, some of them quite interesting and relevant! The evidence for a biological basis of transsexualism keeps just piling on. What also keeps piling on is my stack of articles I still need to work through for publishing on this website … ☹ I’ll hope I’ll get it all done before the Christmas holidays… we’ll see ☺

  • A highly interesting German study from the University of Göttingen by Junger, Habel, Bröhr et al. (PLOS One, 2014) looks at the brain processes for listening and recognising voice. With magnetic resonance imaging technology, they discovered that male-to-female transsexuals showed differences in their neural networks compared to cisgender men and women in the control groups. “With increased voice morphing men recruited more prefrontal areas compared to women and MtFs, while MtFs revealed a pattern more similar to women. On a behavioral and neuronal level, our results support the feeling of MtFs reporting they cannot identify with their assigned sex.

  • A new Turkish study by Bozkurt, Bozkurt and Sonmez, published in the Archives of Sexual Behavior, 2014, looks at the birth order and sibling sex ratio for male-to-female transsexuals. Just like studies in Western countries, a sample higher number of older brothers was found in the Turkish sample – “which suggests a common underlying biological causal mechanism”.

  • A new British study published in the Mental Health Review Journal, 2014, by Bailey (no, not that Bailey), Ellis and McNeil finds extremely high suicide indicators in transsexuals (84 % lifetime prevalence for suicidal ideation and 48 % lifetime prevalence for attempted suicide). The highest risk is prior to social transition, hormone therapy or surgery. “The article highlights the devastating impact that delaying or denying gender reassignment treatment can have and urges commissioners and practitioners to prioritise timely intervention and support.” This adds to the body of evidence that medical intervention is literally a lifesaver for transsexuals.

  • In another British study, Ellis, Bailey (no, not that Bailey), and McNeil look at the experiences transsexual people have with mental health and gender identity services (Journal of Gay & Lesbian Mental Health, 2014). Key findings are “that untreated gender dysphoria (due to delays or refusals of treatment), unnecessary and intrusive questioning/tests, prejudicial attitudes by service providers, and restrictive treatment pathways, all contribute to minority stress which is detrimental to the mental health and wellbeing of trans people”.

  • A Thai study by Yadegarfard, Meinhold-Bergmann and Ho (Journal of LGBT Youth, 2014) finds that depression and suicidal thinking in transsexuals is caused by family rejection, lower social support and higher loneliness.

  • Olvera-Hernández and Fernández-Guasti find (Advances in Neurobiology: Perinatal Programming of Neurodevelopment, 2014) that interrupting oestrogen synthesis in male rats leads to behaviour corresponding to human male homosexual behaviour, reinforcing “the hypothesis that human sexual orientation is underlied by changes in the endocrine milieu during early development”.

  • An older study by Servin, Nordenström, Larsson and Bohlin (Developmental psychology, 2003) looks at girls with the disorder of sexual development CAH. CAH-affected girls are more likely to display boylike behaviour. The researchers looked at links between the degrees of boylike behaviour, the severity of the disease and parental influence: “A relation was found between disease severity and behavior indicating that more severely affected CAH girls were more interested in masculine toys and careers. No parental influence could be demonstrated on play behavior, nor did the comparison of parents' ratings of wished for behavior versus perceived behavior in their daughters indicate an effect of parental expectations. The results are interpreted as supporting a biological contribution to differences in play behavior between girls with and without CAH.”

  • Hines, Brook and Conway found similiar links in 2004 (Journal of sex research). Women with CAH recall more male-typical play in childhood and have a reduced satisfaction with the female gender, while gender-typical play behaviour and gender identity is unaffected in men with CAH. This adds further evidence to the theory that gender-typical play behaviour and gender identity is influenced by the actions of sex hormones before birth.

  • A 2012 study by Alexander and Saenz (Hormones and behaviour) finds “more male-typical digit ratios in early infancy predicted higher activity counts during toy play and less female-typical toy preferences in girls”; meaning that girls who were under the influence of higher androgen levels before birth exhibit more boylike behaviour.

I have more to add later … I’ll see how the weekend is going ☺ Take care!