Over half a million take part in the largest ever study of autism

Theories that suggest men have a natural tendency towards autism have been supported by a major study of over half a million people exploring psychological sex differences.

Professor Simon Baron-Cohen. Picture: wikimedia

Scientists working with producers from Channel 4 tested and confirmed two long-standing psychological theories: the empathising-systemising theory of sex differences and the extreme male brain theory of autism.

The testing process was covered in the Channel 4 programme Are You Autistic? which aired in March, with the results from the research published today. The empathising-systemising theory predicts that women, on average, will score higher than men on tests of empathy, the ability to recognise what another person is thinking or feeling, and to respond to their state of mind with an appropriate emotion. Similarly, it predicts that men, on average, will score higher on tests of systemising, the drive to analyse or build rule-based systems.

The extreme male brain theory predicts autistic people will score lower than the population on tests of empathy and the same as or higher than the typical population on tests of systemising. Both theories have been confirmed in previous studies of modest samples, but the new findings come from a massive sample of 671,606 people, including 36,648 autistic people.

They were replicated in a second sample of 14,354 people. In this new study, the scientists used brief ten-item measures of empathy, systemising, and autistic traits. The measures used were statements with participants asked to rate them on a sliding scale from strongly agree to strongly disagree. Examples included – “I am good at prediciting how someone will feel”. Using these short measures, the team identified in the typical population, women, on average, scored higher than men on empathy, and men, on average, scored higher than women on systemising and autistic traits. These sex differences were reduced in autistic people. On all these measures, autistic people’s scores, on average, were “masculinised”: that is, they had higher scores on systemising and autistic traits and lower scores on empathy, compared to the typical population. Men, on average, had higher autistic trait scores than women.

Prof Simon Baron-Cohen, director of the Autism Research Centre at Cambridge said: “This research provides strong support for both theories. This study also pinpoints qualities autistic people bring to neurodiversity. They are, on average, strong systemisers, meaning they have excellent pattern-recognition skills, excellent attention to detail, and an aptitude in understanding how things work.”