A new report suggests schizophrenia or bipolar disorder in first-degree relatives, such as parents or siblings, may be associated with increased risk of autism spectrum disorder (ASD).
To ascertain if a linkage exists, population health registers in Sweden and Israel were examined by Patrick F. Sullivan M.D., and colleagues at the University of North Carolina at Chapel Hill.
Investigators used the national databases to determine if a family history of schizophrenia, bipolar disorder, or both were risk factors for ASD, a group of developmental brain disorders.
In the study, researchers conducted a case-control evaluation of histories of schizophrenia or bipolar disorder in first-degree relatives of probands (the patients who met the criteria for ASD) from three group samples: two in Sweden and a third of conscripts (recruits to military service) in Israel.
The presence of schizophrenia in parents was associated with a nearly three-fold increased risk for ASD in a Swedish national group sample (odds ratio [OR], 2.9) and a Stockholm County, Sweden, group (OR, 2.9).
Schizophrenia in a sibling also was associated with more than a 2.5 times increased risk for ASD in the Swedish national group (OR, 2.6) and a twelve fold increase among the Israeli conscription group (OR, 12.1).
Bipolar disorder showed a similar pattern of association but of a lesser magnitude, the results indicate.
Although the investigation determined a significant association or linkage between ASDS and schizophrenia, researchers do not understand the clinical or etiological (cause or contributing factor) relationship.
“Our findings indicate that ASD, schizophrenia and bipolar disorders share etiologic risk factors. We suggest that future research could usefully attempt to discern risk factors common to these disorders,” the authors comment.
Their results are published online in the Archives of General Psychiatry.
Source: JAMA and Archives Journals