In a startling revelation, new study demonstrates that relatives of people with autism may display autistic brain differences and behaviours linked to the condition, even though they may not suffer from the disorder themselves.
The work, reported in the New Scientist , was presented at the annual meeting of the Society of Neuroscience, in Washington DC by Dr Eric Peterson, from the University of Colorado in Denver, USA.
Autism, which affects about 5 in 10,000 people, predominantly boys and men, is often also associated with learning disabilities. This disorder makes it hard for the individual to relate socially and emotionally to others.
Dr Peterson compared the brain scans of 40 parents with autistic children with those of 40 matched parents whose children were normal.
It was found that the parents of autistic children shared several differences in brain structure with their offspring, including an unexpected increase in the size of the motor cortex and basal ganglia, both areas linked to movement planning and imitation.
However, the results showed that the neighbouring region - somatosensory cortex, which is important for understanding social information such as facial expressions, a skill which autistic people often lack, was by contrast, smaller than average.
Also, reductions in the cerebellum region were obtained. The cerebellum is important for co-ordinating movement, and is considered to play a key role in understanding the intentions of others.
Experts hope that the work could make it easier to spot families at risk of having an autistic child, and could also help in the quest to find genetic and environmental triggers for the condition.