Although schizophrenia and bipolar disorder are defined as two different disorders, they have some things in common, according to two studies published online June 17 in the American Journal of Psychiatry. The first study, led by Scot Kristian Hill of Rosalind Franklin University, Chicago, Illinois, finds that people with bipolar disorder who also have bouts of psychosis have mental difficulties similar to, but not as pronounced as, those found in people with schizophrenia. In the second study, Pawel Skudlarski of Yale University, New Haven, Connecticut, and colleagues report disruptions in the structure of the brain’s communication byways for both disorders.
The results suggest that schizophrenia and bipolar disorder with psychosis differ in degree, rather than kind of cognition or brain circuit problems. Overlaps between the two disorders have long been recognized, but the studies reflect the first attempts by the Bipolar and Schizophrenia Network on Intermediate Phenotypes (B-SNIP) group, consisting of six centers across the United States, to pinpoint similarities and differences between the two in a standardized setting. This may help distill the complex symptoms of these disorders into their specific component parts—something that could simplify finding the contributing genes. As a first step, the researchers also examined healthy relatives of the people with schizophrenia or bipolar and found milder forms of the mental difficulties and disrupted brain connections. This suggests these features are inherited and could lead to genes involved in the disorders. (For more details, see the related news story.)—Michele Solis.