Magazine article Clinical Psychiatry News

Schizophrenia-Bipolar I Theory Gains Traction

Magazine article Clinical Psychiatry News

Schizophrenia-Bipolar I Theory Gains Traction

Article excerpt

NEW YORK -- From their first classification by Emil Kraepelin late in the 19th century, bipolar I disorder and schizophrenia have been considered distinct disease entities. But in recent years, clinicians and researchers have increasingly questioned whether the diagnoses represent points on a single continuum.

"There's more and more evidence for the continuity theory," Dolores Malaspina, M.D., said at a conference on schizophrenia sponsored by Columbia University.

Common genetic and other risk factors, similarities in epidemiology, and overlapping signs and symptoms argue against a strict dichotomy between the disorders, she said.

The prevalence of schizophrenia and bipolar I disorder is comparable--about 1% for each--and both are equally distributed between men and women. The mean age of onset for each is before the end of the 20s, and both are associated with increased risk of suicide, cigarette smoking, and substance abuse, said Dr. Malaspina, professor of clinical psychiatry at the university.

Brain imaging studies show similarities as well. Ventricles are enlarged, and frontal lobe and hippocampal volumes are reduced in both disorders, as is cortical gray matter. The frontal lobe reductions are attributable to losses in different neural networks, however, and anatomical changes are more striking and progressive in schizophrenia, she said.

Extreme sensitivity to stress is a common factor. Even daily hassles may lead to deterioration and cognitive problems. The impact of stress on dopamine release may be the underlying mechanism in bipolar and schizophrenia exacerbations.

Both disorders clearly involve a mix of environmental and genetic factors. Illness in first-degree relatives increases risk in comparable ways: having one affected parent carries a 10% risk in the case of schizophrenia, and a 25% risk for bipolar disorder; if both parents are affected, the risk rises to 25% for schizophrenia and 50% for bipolar disorder. …

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