Researchers in Sweden are assembling a large group of identical twin pairs, with only one twin in each pair having autism.

The MacArthur Foundation honors neuroscientist Beth Stevens, and researchers pin down factors that influence the placebo effect in autism trials.

Autism is not a developmental disorder, but rather the brain’s adaptive response to early genetic or environmental disturbances, says Mark Johnson.

The National Institutes of Health is reviving a defunct study that aimed to identify environmental risk factors for autism and other childhood disorders. Some researchers say the do-over is unlikely to live up to the original project’s promise.

Contrary to previous findings, children born by cesarean section are not at an increased risk of autism, says a Swedish sibling study.

Marmosets exposed to an epilepsy drug in the womb do not recognize reciprocity — the social give-and-take that is a challenge for some people with autism — suggests a new study. The findings add to mounting evidence that these tiny monkeys offer clues about autism.

Women who are overweight while pregnant have an increased risk of having a child with autism. But a new study suggests that genetics, not the obesity per se, underlies the association.

Telomeres, the structures at the tips of chromosomes, tend to be unusually short in people with autism and their immediate family members.

Older women and men are at high risk of having a child with autism — and so are teenage girls and parents whose age differs by at least a decade, according to a multinational study of more than 5 million children.

Monkeys whose mothers are infected with a mock virus while pregnant show abnormal branching of certain brain cells. The findings may help explain why infection during a woman’s pregnancy ups the risk of autism in her children.