Genes linked with a greater risk of developing autism may also be associated with higher intelligence, a new study suggests. The findings provide new evidence linking genetic factors associated with autism to better cognitive ability in people who do not have the condition.
The research was published this week in the journal Molecular Psychiatry.
“Our findings show that genetic variation which increases risk for autism is associated with better cognitive ability in non-autistic individuals,” said the study’s lead author, Dr. Toni-Kim Clarke, of the University of Edinburgh’s Division of Psychiatry. “As we begin to understand how genetic variants associated with autism impact brain function, we may begin to further understand the nature of autistic intelligence.”
The relationship between autism and intelligence is not clear, researchers say. Although up to 70 percent of individuals with autism have an intellectual disability, some people with the disorder have relatively well-preserved, or even higher than average, non-verbal intelligence, the team says.
Non-verbal intelligence enables people to solve complex problems using visual and hands-on reasoning skills requiring little or no use of language, which is often impaired in children with autism.
For the study, researchers analyzed almost 10,000 people recruited from the general population of Scotland. Individuals were tested for general cognitive ability and had their DNA analyzed.
The team found that even among people who never develop autism, carrying genetic traits associated with the disorder is, on average, linked to scoring slightly better on cognitive tests. The researchers found further evidence of a link between autism-associated genes and intelligence when they carried out the same tests on 921 adolescents who were part of the Brisbane Adolescent Twin Study.
“Links between autism and better cognitive function have been suspected and are widely implied by the well-known ‘Silicon Valley syndrome’ and films such as Rain Man as well as in popular literature,” noted co-author Dr. Nick Martin, of the Queensland Institute for Medical Research.
“This study suggests genes for autism may actually confer, on average, a small intellectual advantage in those who carry them, provided they are not affected by autism,” added Dr. Martin.