Differences between male and female brains in autism

Dr Melissa Kirkovski

by Anne Crawford

Australian males are estimated to be four times more likely than females to be diagnosed with Autism Spectrum Disorder (ASD). The mechanisms that make them more prone to the condition are currently a hot topic of research in the field. 

A former Central Clinical School (CCS) graduate student was part of a study by the MonashAlfred Psychiatry research centre (MAPrc), the CCS and others that found gender differences in a region in the brain implicated in social understanding – a core part of impairment in people with ASD. The research was part of a PhD thesis that later earned Dr Melissa Kirkovski an international award.

Dr Kirkovski used fMRI (functional Magnetic Resonance Imaging) to investigate differences between the sexes in brain activity in adults with high-functioning ASD, comparing this with a control group of people without the condition. She was supervised by Professor Paul Fitzgerald at MAPrc and Associate Professor Peter Enticott from Deakin University’s Cognitive Neuroscience Unit.

“At the time we set up the study there was a little bit of literature indicating there were differences between males and females with autism at a brain-based level but it was unclear what these differences were,” Dr Kirkovski said. “We wanted to take this a step further and see whether or not there were any functional brain-based differences and where these differences were located,” she said.

The researchers showed 50 participants videos with two floating ‘characters’ that interacted physically and emotionally, testing brain activity as they watched using fMRI.  

The fMRI showed that males with ASD had reduced brain activity in the posterior superior temporal sulcus, a part of the brain strongly implicated in social understanding, but there was no evidence of this in females with ASD.

“This was a novel finding at the time, not reported previously,” Dr Kirkovski said. 

“It was one of the early studies looking at the functional neurobiological underpinnings of sex differences in autism. It’s suggesting that we need to look more closely at this,” she said.

The study concludes that the findings could serve as an important guide for future brain-based intervention for autism.

“Understanding the differences between the sexes is really important for understanding how we diagnose Autism Spectrum Disorder and, in the future, how we treat it,” Dr Kirkovski said. “Further research would also help us tailor treatment to clinical needs,” she said.

The study was part of a PhD project that earned Dr Kirkovski, a neuroscientist, the 2016 International Society for Autism Research (INSAR) Distinguished Dissertation Award, which she received at the society’s annual conference in Baltimore in May.

She said that researchers at conferences elsewhere have also expressed interest in the study and that the study participants appreciated it.

Dr Kirkovski is now a research fellow at Deakin University's Cognitive Neuroscience Unit.

Kirkovski M, Enticott PG, Hughes ME, Rossell SL, Fitzgerald PB. Atypical Neural Activity in Males But Not Females with Autism Spectrum Disorder. J Autism Dev Disord. 2016 Mar;46(3):954-63. doi: 10.1007/s10803-015-2639-7.