Children whose parents or siblings have been diagnosed with schizophrenia or bipolar disorder have a higher risk of of autism spectrum disorders (ASDs).

The results of a study were published online in the Archives of General Psychiatry, by medical geneticists from North Carolina's School of Medicine University who wanted to evaluate to which degree these disorders are linked in view of the statement "has important implications for clinicians, researchers and those affected by the disorders."

The researchers conducted a case-control study with data obtained from population registers in Sweden and Israel. Patrick F. Sullivan, MD, FRANZCP, professor in the department of genetics and director of psychiatric genomics at UNC declared: "The results were very consistent in large samples from several different countries and lead us to believe that autism and schizophrenia are more similar than we had thought."

Sullivan and his team discovered that the risk for ASD in Stockholm and the entire country of Sweden was nearly three times higher in those whose parents suffered from schizophrenia, whilst siblings with schizophrenia were associated with an approximate 2.5-times higher risk of autism in the Swedish national group and a 12-times higher risk in a sample of Israeli military personnel.

According to the researchers, the higher risk in Israelis could potentially be because of individuals who had an earlier onset of schizophrenia, "which has a higher sibling recurrence."

The results also demonstrated that the linked pattern for bipolar disorder was similar, but of a lesser magnitude.

The researchers conclude that ASD, schizophrenia, and bipolar disorder share etiologic risk factors, saying: "We suggest that future research could usefully attempt to discern risk factors common to these disorders."

Written by Petra Rattue