Male monkeys that avoid touching, grooming or playing with others have low brain levels of the hormone vasopressin.

Girls with an autism diagnosis have more severe impairments in social communication than boys with the diagnosis.

Missing one copy of a stretch of chromosome 16 leads to an enlarged brain; an extra copy of the region has the opposite effect.

Children with autism often have problems understanding others’ thoughts; those who use mental strategies to compensate for these problems may be unusually anxious.

A widely used test for autism misses some children with delays in motor, social and communication skills.

Many women with autism or attention deficit hyperactivity disorder report having been sexually abused as a child.

Many children eventually diagnosed with autism lose social skills between 18 months and 3 years of age. But few parents notice this trend.

A greater proportion of 3-year-old girls than boys with autism have psychiatric features such as anxiety and moodiness.

The proportion of children with autism considered to be minimally verbal in a study depends on the criteria researchers use to identify them.

Children with autism show much less restraint when confronted with one of their interests, compared with their typical peers.