Rethinking How We Diagnose Psychosis - A new study opens a door to more biologically based categories of major mental illness

Moving psychiatry into a new era of biologically based diagnosis has been a long sought goal—and a priority at the National Institutes of Mental Health (NIMH)

A study led by neuroscientist Brett Clementz of the University of Georgia, psychiatrist Carol Tamminga of the University of Texas, and colleagues at Yale and Harvard found distinct “biotypes” of psychosis that can be identified with quantitative biomarkers.

In this study, from the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) consortium, 711 people with a diagnosis of schizophrenia, bipolar disorder, or schizo-affective disorder (a hybrid of schizophrenia and bipolar disorder) were assessed with what the investigators call a brain-based panel of cognitive tests, studies of eye movements, a test of cognitive control, and electro-encephalogram. In addition, each subject had a brain imaging scan.

Ignoring the clinical diagnosis, researchers pooled the data and analyzed it with unbiased, criterion-free statistical methods to look for what they called biotypes. Perhaps it is not surprising that the computer analysis from a large population with three diagnostic categories would find three clusters or biotypes.

But the three biotypes have very little relationship to the three diagnostic categories. In fact, people with schizophrenia and bipolar and schizo-affective disorders were distributed across the three biotypes.

And the biotypes did not differ simply by symptom severity or the presence of mania-related symptoms.

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