AUTISM genes may be linked to higher intelligence, a study of almost 10,000 Scots suggests.

Genetic factors thought to play a role in autism are associated with heightened mental ability in people who do not have the developmental condition, researchers in Edinburgh and Australia have found.

The teams of scientists claim the relationship between autism and intelligence is not clear, with up to 70 per cent of individuals with the condition having an intellectual disability.

However, some people with the disorder have relatively well-preserved, or even higher than average, non-verbal intelligence, the team said.

Researchers at the Edinburgh University and Queensland analysed almost 10,000 people recruited from the general population of Scotland. Individuals were tested for general cognitive ability and had their DNA analysed.

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.

Further evidence of the association emerged when the same tests were carried out on 921 teenagers who were participants in the Australian twin study.

The team said that while autism was a developmental disability that can cause significant language and speech difficulties, non-verbal intelligence enables people to solve complex problems using visual and hands-on reasoning skills requiring little or no use of language.

Dr Toni-Kim Clarke, of Edinburgh University's Division of Psychiatry, who led the study, said: "Our findings show that genetic variation which increases risk for autism is associated with better cognitive ability in non-autistic individuals.

"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."

Co-author Professor Nick Martin, from the Queensland Institute for Medical Research, said: "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.

"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."

The study comes on the back of pioneering research by Aberdeen-based academics which suggests autism sufferers' brains can be "retrained" to understand the gestures and body language which they normally find confusing and which make social interaction challenging.

Aberdeen University scientist Dr James Cusack, who has autism himself, found in his four-year study that generalisations about people with the condition being poorer at interpreting physical cues may be exaggerated and could be overcome by developing their ability to pay attention to signals in their brain which may otherwise go unnoticed.

The results showed that ability to detect subtle differences was significantly higher than previously thought.

Further recent research has also suggested many girls could be suffering with undiagnosed autism as they are better at covering up signs of the disorder compared to boys.

According to the report, teachers are six times more likely to identify boys as having autism spectrum disorder (ASD) than girls, with parents twice as likely to make the same assessment.