The data indicate that the autism rise is partly the result of students being moved from one category to another, Girirajan says.
For him, one lesson is that autism encompasses a potpourri of symptoms. It can also occur hand-in-hand with other conditions including intellectual disabilities, epilepsy, and attention-deficit hyperactivity disorder. That mixture makes it hard to pin down how common autism really is, and lends itself to shifting diagnoses, he says.
The findings, reported today in the
American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, underscore the growing acceptance within institutions and families of a condition once either ignored or avoided as a mark of shame, says Roy Richard Grinker, an anthropologist at George Washington University in Washington, D.C., who has studied autism rates and wrote a book about autism,
Unstrange Minds. He points to a recent
Washington Post article about the emergence of groups of autistic adults advocating for acceptance through events like "Autistic Pride Day."
"What this paper is saying is that autism is increasingly being embraced as a useful, acceptable, less stigmatizing framework," says Grinker, who has an autistic daughter.
There are some risk factors that might account for a small amount of the increase in autism cases, says Jon Baio, a Centers for Disease Control and Prevention (CDC) epidemiologist and principal investigator for an autism monitoring program. That includes children born premature or underweight. A recent study in the journal
Molecular Psychiatry found that older fathers, and older or teenage mothers had a higher risk of having children with autism.
