Transdiagnostic Brain Network for Psychiatric Illness Identified
Researchers from Brigham and Women’s Hospital, Boston, Massachusetts, have identified a significant, sensitive, and specific transdiagnostic network underlying several psychiatric illnesses. They published their study online ahead of print in Nature Human Behavior.
“Psychiatric disorders are brain disorders, and now we’re just beginning to have the tools to study and modulate their underlying circuitry,” said corresponding author Joseph J. Taylor, MD, PhD, medical director of Transcranial Magnetic Stimulation at the Brigham’s Center for Brain Circuit Therapeutics and an associate psychiatrist in the department of psychiatry. “There may be more in common across these disorders than we originally thought.”
An analysis of structural brain data from over 15,000 healthy controls and patients with schizophrenia, bipolar disorder, depression, addiction, obsessive-compulsive disorder, or anxiety revealed gray matter decreases in anterior cingulate and insula, the research team explained. Although the two brain regions are commonly linked with psychiatric illness, the gray matter decreases occurred in just a third of studies — and similar decreases were found in patients with neurodegenerative disorders.
The team then used a human connectome to see if gray matter changes in psychiatric illness better mapped to a common brain network rather than to regions. Testing revealed a transdiagnostic network in which up to 85% of studies showed gray matter decreases specific to psychiatric disorders. When investigators re-ran the data, leaving out one psychiatric diagnosis at a time, the network remained robust. In other words, no single psychiatric disorder was disproportionately responsible.
In another analysis of 194 veterans with and without penetrating head trauma, lesion damage to the transdiagnostic network correlated with a higher likelihood of multiple psychiatric illnesses, according to the research team. In a final test, data from neurosurgical ablations for patients with extreme psychiatric illness showed that the ablation targets aligned with the identified transdiagnostic network.
Interestingly, findings challenged the idea that gray matter decreases in anterior cingulate and insula are causally associated with psychiatric illness, Dr Taylor pointed out.
“We found that lesions to those regions were correlated with less psychiatric illness, not more,” he said, “so atrophy in that cingulate and insula may be a consequence or a compensation for psychiatric illness rather than a cause of it.”
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