Brain abnormality linked to general risk for mental illness

A new study by researchers at Duke University reports an abnormality in visual regions of the brain that is associated with a person's general risk for mental illness. The findings, published in Biological Psychiatry, indicate a signature abnormality shared between common forms of mental illness, which could help clinicians assess a patient's general risk for developing a mental illness. The signature abnormality was present in participants involved in the study who already had a higher risk of mental illness. This was characterized by a reduced efficiency between visual areas and brain networks important for integrating sensory information and suppressing distracting information.

Researchers have long thought that some aspects of the biology of the risk for psychiatric disorders were specific to particular disorders, and by studying specific groups of patients, may have mistaken general risk factors as specific risk factors. Newer research suggests that a person's risk for developing mental illness is not specific to one form of disorder, but is instead shared across many different disorders. "In other words, there may be a single risk factor that predicts whether an individual develops any form of psychiatric disorder, be it depression, post-traumatic stress disorder, addiction, or even schizophrenia," said first author Maxwell Elliott, a doctoral student in the laboratory of Ahmad Hariri, PhD.

"In this paper by Elliott and colleagues, reduced cortical efficiency may be one of these general risk traits," said John Krystal, MD, Editor of Biological Psychiatry.

The 605 university students included in the study were a subset from the larger Duke Neurogenetics Study. Many of the participants met criteria for psychiatric disorders, including alcohol or substance use disorder, major depressive disorder, and bipolar disorder. However, rather than dividing the participants by a specific diagnosis, Elliott and colleagues gave each person a score that reflected their general mental health liability based on psychiatric assessments.

Functional magnetic resonance imaging (fMRI) of the whole brain identified a relationship between the individual scores and increased connectivity between the visual cortex and specific brain networks important for high level thinking. The networks, referred to as default mode network and frontoparietal network, are critical for behaviors aimed at completing a particular task, and suppressing internal distractions to tease out sensory information relevant to that task.

"These patterns suggest that broad risk for mental illness may reflect subtle problems in how a person is able to integrate their thoughts, plans, and actions with their fundamental experience of the world, which in humans is principally represented by visual information," said Mr. Elliott.

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