Autism can also be divided into syndromal and non-syndromal autism, where the former is as

In a pair of studies, high-functioning autistic children aged 8-15 performed equally well, and adults better than individually matched controls at basic language tasks involving vocabulary and spelling. Both autistic groups performed worse than controls at complex language tasks such as figurative l

Heritability contributes a large fraction of the risk of a child's developing the disorder, although the genetics of autism are complex, and it is generally unclear which genes are responsible. In rare cases, autism is strongly associated with agents that cause birth defects. Other proposed causes, such as the exposure of children to vaccines, are controversial and the vaccine hypotheses are unsupported by convincing scientific evidence.