Using Brain-based Biomarkers, Researchers Identify Three Psychosis Biotypes
A research team has established a set of empirical biomarkers to aid in the diagnosis and treatment of psychosis. The study, published in the American Journal of Psychiatry, identifies a trio of neurobiologically distinct biotypes that do not always match with conventional, symptom-based diagnoses.
"In a sense, we have totally deconstructed and rethought the basis for diagnosis in psychosis," said researcher Carol Tamminga, MD, chair of psychiatry at the UT Southwestern Medical Center in Dallas. "Building diagnoses based on biology, not just phenomenology, makes it possible for the biological bases of these brain disorders to stand out as molecular targets for disease definition and novel treatments."
"In the end, we found the term 'psychosis' might actually describe a number of unique psychiatric disorders, just as the term 'congestive heart failure' might describe a range of cardiac, renal, and pulmonary disorders, each having distinctive mechanisms and treated with specific remedies," added researcher Elena Ivleva, MD, PhD, assistant professor of psychiatry at UT Southwestern.
Researchers identified three distinct “biotypes” of psychoses after evaluating 711 people with psychosis, 883 of their first-degree relatives, and 278 healthy control subjects. Each participant went through a series of cognitive, eye tracking, electroencephalography (EEG), and magnetic resonance imaging tests.
Of the observed biotypes:
- Biotype 1 was the most impaired, according to researchers. Patients demonstrated poor cognition and eye tracking and the most brain tissue damage. All of the usual psychosis diagnoses appeared in Biotype 1, but schizophrenia cases were slightly predominant.
- Biotype 2 demonstrated cognitive impairment, poor eye tracking, and high brain wave response, with patients often rated as overstimulated, hyperactive, or hypersensitive. Biotype 2 had worse scores on mood scales, such as depression and mania.
- Biotype 3 was the least impaired. Subjects had near-normal evaluations of cognition, EEG function, and brain structure and were slightly more likely to be diagnosed with bipolar disorder.
"What's puzzling and fascinating at the same time,” said Dr. Tamminga, “is that all three biologically driven disease constructs, or biotypes, might be clinically diagnosed as having schizophrenia, schizoaffective, or bipolar disorder.”
The Bipolar-Schizophrenia Network on Intermediate Phenotypes research team included researchers from UT Southwestern, Harvard University, Yale University, the University of Chicago, and the University of Georgia.
—Jolynn Tumolo
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