A new study published online in the Archives of General Psychiatry on July 2 found that a family history of schizophrenia and/or bipolar disorder is a risk factor for autism.

Patrick F. Sullivan, M.D., Professor and Director of Psychiatric Genonomics at the University of North Carolina School of Medicine was the lead author of the new study. Dr. Sullivan was a recipient of a NARSAD Distinguished Investigator Grant in 2010. Sullivan and colleagues found that the autism risk was almost three-times greater with schizophrenia in parents and 2.6- to 12.1-times greater with schizophrenia in a sibling across various cohorts. Bipolar disorder showed a similar pattern of association but of a lesser magnitude.

The study authors wrote that the degree to which the three illnesses share a basis in causation “has important implications for clinicians, researchers and those affected by the disorders.” The findings suggest that schizophrenia, bipolar disorder, and autism are different manifestations of the same root causes. The common factors could be shared DNA sequence variation, a common environmental risk factor the whole family is exposed to, or a gene-environment interaction, Sullivan and colleagues suggested.

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