Female infants have more grey matter in their temporal-parietal junction or TPJ than males, a new study found. This region in the brain is responsible for social information processing seen in the faces of other people, an ability that is impaired in people with autism spectrum disorders.
Researchers from the University of North Carolina in Chapel Hill presented their study at the annual meeting of the American College of Neuropsychopharmacology. They found that female infants have more grey matter volumes around the TPJ region of the brain than males at the time of birth.
According to the researchers, sex differences in this specific region of the brain may shed light in the reason why males are at a higher risk of autism spectrum disorders. To land to their findings, Dr. Rebecca Knickmeyer, lead author of the study and her co-authors analyzed sex differences in the brain development of more than 800 infants upon birth.
They were followed for two years as they underwent brain imaging tests and measures of sex hormones in the saliva. Apparently, another finding emerged, as the researchers discovered that myelination of long fiber tracks in the brain is more developed in males than in females.
Myelination means the formation of a myelin sheath around nerves to allow nerve impulses to move more quickly. Also, female infants are more prone to a disease called Turner's syndrome.
They undergo a significant decline in brain volume in the inferior parietal lobes, an area in the brain just above the TPJ. Thus, they concluded that the volume in the parietal lobe volume can be influenced by sex chromosomes in females.
Many studies in the past suggest that males are at a higher risk of autism than females. In fact, in a 2009 study, they found that 1.8 percent of men who participated in the survey had autism compared to 0.2 percent of women.
Another study shows that in 2015, the ratio of men who avail of NAS (National Autistic Society) services was around three is to one. On the other hand, those who attended NAS schools were five males is to one female.
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