Researchers Find Similar Brain-Matter Loss Across Several Psychiatric Disorders

Psychiatric disorders such as schizophrenia, bipolar disorder, and major depression seem fairly distinct from each other when they appear, but a new report suggests they have something in common. Numerous separate psychiatric disorders cause similar brain-matter loss.

The report, published in JAMA Psychiatry, shows a loss of gray matter in three specific brain structures that work within a network associated with high-level functions such as planning and decision-making. The findings indicate there may be more in common between a wide spectrum of psychiatric disorders than previously understood.

The new study used older studies that tended to focus on psychiatric disorders in isolation. Instead, the new research team “have stepped back from the trees to look at the forest and see a pattern in that forest that wasn’t apparent when you just look at the trees,” said Thomas Insel, MD, director of the National Institute of Mental Health, who wasn’t involved in the study but is familiar with its contents.

“In many of these published studies we reviewed, researchers have tended to interpret their biological findings in terms of the one disorder they’re focusing on,” said Amit Etkin, MD, PhD, an assistant professor of psychiatry and behavioral sciences at Stanford and the study’s senior author. Lead authorship is shared by Madeleine Goodkind, PhD, a postdoctoral scholar in Etkin’s group, and Simon Eickhoff, DrMed, a professor of clinical neuroscience and medical psychology at Heinrich-Heine University Dusseldorf.

Etkin says the team started by asking a simple question: “Is there any common biological basis for mental illness?”

To find the answer, Etkin and his team gathered data from 193 separate studies containing, in all, magnetic-resonance images of the brains of 7,381 patients falling into six diagnostic categories: schizophrenia, bipolar disorder, major depression, addiction, obsessive-compulsive disorder and a small group of related anxiety disorders.

By comparing these images with those collected from over 8,500 healthy control participants, the research team saw three distinct brain structures separated by several centimeters which all showed a diminished volume of gray matter. These structures – the left and right anterior insula and dorsal anterior cingulate – are parts of a larger network in the brain which is associated with higher-level executive functions including concentration, multitasking, or task-switching.

The reduction in gray matter was similar across patients with different psychiatric conditions.

Etkin described the structures affected as an alarm bell. “They work together, signaling to other brain regions when reality deviates from expectations—that something important and unpredicted has happened, or something important has failed to happen.”

While the reduction in gray matter was consistent across disorders, many disorders also showed additional gray-matter loss in areas distinct to their diagnosis. People diagnosed with major depression had gray-matter loss in the hippocampus and amygdala, while schizophrenia was marked by a reduced gray matter in several other structures and an increase in gray-matter in the striatum.

“I wouldn’t have expected these results. I’ve been working under the assumption that we can use neuroimaging to help classify the different forms of mental illness,” Insel said. “This makes it harder.”

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