Parents of autistic children are twice as likely to have been hospitalized for a serious mental disorder than the parents of children without the disorder, suggests new research.

A review of Swedish birth and hospital records by U.S. researchers reveals that if a child is autistic, their parents are twice as likely as other parents to have been hospitalized for a psychiatric disorder like schizophrenia.

Depression and personality disorders were more common among mothers of autistic children (1.2 times more likely) than among mothers of non-autistic kids, suggests the study, published in Monday's issue of the journal Pediatrics.

The study looked at 1,237 children born between 1977 and 2003 who were diagnosed with autism before age 10. To be deemed autistic, the children all had to have received a diagnosis of autism disorder, Asperger Syndrome or pervasive developmental disorder.

Asperger Syndrome is a variant of autism in which individuals often exhibit extensive knowledge of a specific interest. Symptoms of pervasive developmental disorder include impairments in social interaction, imaginative activity, verbal and non-verbal communication skills, and a limited number of interests and activities that tend to be repetitive.

Seventy-seven per cent of the children involved in the study were boys.

"These results support those of smaller studies that indicated an increase in psychiatric conditions among parents of children with autism, specifically schizophrenia, neurotic disorders and depression," write the authors. "Identifying families with a propensity for rare psychiatric conditions may help uncover rare genes that contribute to the susceptibility of both disorders."

Other mental conditions in parents evaluated in the study were affective disorders, neurotic and personality disorders, and non-psychotic disorders, alcohol and drug addiction, and abuse.

The autistic children were compared to 30,925 kids who were matched in terms of gender, age and hospital.