Despite gender bias in autism spectrum disorders being well-known, the biological basis of the disorders has remained unclear. This has partly been due to a lack of understanding of sex differences in brain development. A new study published in the American College of Neuropsychopharmacology however has recently delved into this problem, providing essential information on key differences between male and female brain regions during development.
By assessing over 800 healthy newborn children for 2 years, utilizing brain imaging and measures of sex hormones in saliva, researchers from the University of North Carolina Chapel Hill (NC, USA) have successfully characterized sex differences in brain development in the temporal-parietal junction.
Female infants were found to possess larger volumes of gray matter around the temporal-parietal junction of the brain compared to males at the time of the birth. This temporal-parietal junction enables processing of social information from facial expressions and voices, a function that is impaired in individuals with autism spectrum disorders.
The study also found that by the age of two, myelination of long fiber tracks is more developed in males, allowing neurons to transmit information more quickly. Additionally, the genetic disorder Turner Syndrome (which only affects females) was also found to be linked to a significant reduction in brain volume in the inferior parietal lobes.
These results suggest that inferior lobe volume can be influenced in part by sex chromosomes and go some way in explaining the gender bias within autism spectrum disorders in addition to some other neurodevelopmental disorders.
Source: American College of Neuropsychopharmacology press release