Atypical gender development: biological explanations to gender dysphoria Flashcards
What is the brain sex theory
Gender dysphoria is caused by over or under exposure to androgens in the womb - over exposure for females and under exposure to males
This has lead to changes in the physical structure of the brain
The presence of testosterone in the third trimester of male babies leads to a masculinised brain
What is the BSTc
The bed nucleus of the stria terminalis
What is the difference in BSTc in males and females
It develops differently in males and females it begins development in the womb and is thought to be fully developed by age 5
It is usually 40% larger in males than females
When is the BSTc developed and when does it start to development
it begins development in the womb and is thought to be fully developed by age 5
What did Ning zhou find
Post mortem studies have found the BSTc to 6 male to female transgender individuals to be a similar size to that of the typical female brain
kruijver et al
Conducted a follow up study studying the BSTc but focused on the number of neurons in the BSTc
They found that the 6 male to female transgender individuals had the expected number of neural connections that you would find in a typical female brain
Genetics
Gender dysphoria may have a genetic basis
Researchers have found that biological males with gender dysphoria have variations in the genes responsible for androgen reception
This change reduces effect of testosterone on the body resulting in feminisation
Coolidge
Assessed 157 twin pairs for evidence of gender dysphoria using clinical diagnosis of criteria in the DSM4
The prevalence of gender dysphoria was estimated to be 2.3% with 62% of cases said to be accounted for by genetic variance
This suggests a strong heritable component in gender dysphoria
Heylens
Compared 24 monozygotic twins with 21 DZ twins
One of each pair was diagnosed with gender dysphoria
They found that 39% of MZ twins were concordant for gender dysphoria compared with 0% of DZs
Van beijstervelt
Childhood gender identity data was collected from over 8000 twin pairs - longitudinal twin study
70% of variance in gender identity was due to genetic factors suggesting that atypical gender development is heritable
Results also showed that girls with female co twins were more likely to show cross gender behaviour than girls with male co twins - opposite to what social learning theory would suggest
This suggests it’s biological
Falgeuras
Post mortem analysis on anterior hypothalamus
Volume and number of neurons in male to female transgendered people was more similar to female controls than male controls
Suggests that anterior hypothalamus is implicated in gender dysphoria and it is a result of sexual differentiation in the brain
Theisen
Sequenced genomes of 13 transgenders and compared to 88 controls
Found 21 gene variations associated with oestrogen receptors in the brain to be different in males and females even before birth
This suggests that sex hormone exposure before birth results in sexually dimorphic brain development contributing to gender dysphoria
