One hypothesis that has been advanced to account for the cognitive style in autism spectrum disorders (ASD), is referred to as "the extreme male brain". This model views ASD as resulting from increased testosterone exposure in utero. However, many adults with ASD appear androgynous, youngish for their age and are ambiguous in sexual preferences according to clinical observations. Also, ASD is common in gender identity disorder.
Objectives:
The present study aims to examine testosterone levels and signs of masculinization / feminization in adults with ASD compared to healthy controls.
Methods:
50 adults (24 females and 26 males) with an established diagnose of ASD and without intellectual disability, and 53 age and sex matched healthy controls participated in this study. The ASD diagnosis was confirmed with the ADOS interview. All subjects were photographed in underwear. Circumference of head, wrists, chest, waist and hip were measured with tape measure and second to fourth digit ratio (2D:4D) was measured with a caliper from the middle of the proximal crease to the fingertip. The participants’ voices were recorded while they were reading a short story. Blood test for analyses of serum testosterone (sT) and bioactive testosterone were drawn between 9 AM and 1.20 PM in all participants.
Eight independent observers, 18-47 years, assessed the extent to which the participants’ appearance was considered to be gender-characteristic. The characteristics were estimated based on a 5-point likert scale. Masculinization / feminization of the voices were judged accordingly. Inter-rater reliability was calculated using Cronbach’s alpha. A sample of the photos was re-evaluated a month later to assess intra-rater reliability.
Results:
Females with ASD had higher total and bioactive testosterone levels, less feminine facial features and larger head circumference than female controls. Males in the ASD group were assessed as having less masculine body characteristics and voice quality, and displayed higher (i.e. less masculine) 2D:4D ratios, but similar testosterone levels as compared to controls. Androgynous facial features correlated strongly and positively with autistic traits measured with The Autism-Spectrum Quotient in the total sample.
Conclusions:
Our findings suggest that ASD, rather than being characterized by masculinization in both sexes, may constitute a gender defiant disorder.
See more of: Clinical Phenotype
See more of: Symptoms, Diagnosis & Phenotype