The study, published in Pediatrics, said the parents of children with autism were about twice as likely to have been hospitalized for mental disorders -- such as schizophrenia -- than the parents of other children.

"We also saw higher rates of depression and personality disorders among mothers, but not fathers," study author Julie Daniels of the University of North Carolina at Chapel Hill said in a statement. "Establishing an association between autism and other psychiatric disorders might enable future investigators to better focus on genetic and environmental factors that might be shared among these disorders."

The study examined 1,237 children born in Sweden between 1977 and 2003 who were diagnosed with autism before age 10, and compared them with 30,925 control subjects matched for gender, year of birth and hospital.

The large sample size enabled researchers to distinguish between psychiatric histories of mothers versus fathers in relation to autism, Daniels said. The association was present regardless of the timing of the parent's diagnosis relative to the child's diagnosis.