Autism may shape the brains of women differently to those of men. The condition seems to cause female, but not male, brains to look more masculine, suggesting that one controversial view of autism – as an extreme version of the male brain – may need rethinking.
Simon Baron-Cohen at the Autism Research Centre in Cambridge, UK, has previously found that men tend to be better at systematising tasks and females better at ones involving empathising. As people with autism tend to be good systematisers and below-average empathisers, he has argued that autism may be an extreme version of the male brain, or EMB.
However, the theory is contentious. “The jury is still out,” says autism researcher Uta Frith of University College London. That’s partly because of the difficulty in pinning down the source of the gender differences. “It’s far from clear which male-female differences are biological and which are cultural,” says developmental psychologist Caspar Addyman, of the Birkbeck Babylab at the University of London.
In their latest study, Baron-Cohen’s team used MRI scans to look for differences in the volume of brain regions in 120 adults, split into four equal groups – men and women, with and without autism. The researchers first compared the brains of males with and without autism, then did the same for female brains. They then compared these two differences. “If autism manifests the same in both genders, these two differences should be alike,” says Baron-Cohen’s colleague at the Autism Research Centre Meng-Chuan Lai, “but if not, they should be different – and this is what we found.”
Some of these differences were in the size of certain areas. The researchers also found that autism affected almost completely different brain regions in men and women.
Differences between females with and without autism resembled the differences between non-autistic male and female brains, supporting the EMB theory. However, the brains of males with autism were no more male than those without.”The theory seems to fit with the female brain findings, but not the male brain,” says Frith. “This is unexpected and will lead to a modification of EMB theory.”
It may be harder to see increased maleness in already male brains. The results also hinted that the brains of males with autism are feminised, perhaps implying that the condition is associated with less-gendered brains – but these effects were less clear-cut.
Lai cautions that they only included high-functioning adults with autism in the study. This means, Lai says, that these results should not be generalised to other age groups or those people with intellectual disabilities as well as autism. “We need other studies to investigate whether these differences are present in these other groups,” he says.