Scientists suggest this discovery may partially explain the high rates of co-occurring mental health conditions.
Mental health conditions such as anxiety and depression can often occur together. Because of this overlap, scientists suspect there may be a neurobiological explanation for several different psychiatric disorders.
To investigate this theory further, researchers from Brigham and Woman’s Hospital examined 193 studies to determine if various mental health conditions share a common brain network. Their findings appear in Nature Human Behavior.
The team analyzed the brain data from over 15,000 people without a mental health condition and those diagnosed with depression, schizophrenia, bipolar disorder (BD), anxiety, obsessive-compulsive disorder (OCD), and substance use disorder (SUD).
In one-third of the studies examined, the scientists found decreased gray matter in the anterior cingulate and insula — two brain regions associated with mental health conditions. However, neurodegenerative disorders also showed reductions in gray matter in these regions.
But when the team used a wiring diagram of the brain to test network connections, they found a transdiagnostic network specific to gray matter changes associated with mental health conditions — not neurodegenerative disorders.
Investigating further, the team found that no individual mental health condition was responsible for the network they found.
In addition, after analyzing the brain imaging from people with head trauma and a mental health condition, the team found that trauma-induced lesions in the transdiagnosis network increased the likelihood of multiple psychiatric conditions. Moreover, neurosurgical ablation brain data from people with severe mental health disorders also aligned with the network.
According to a news release, the authors note their discovery seems to challenge the idea that decreases in anterior cingulate and insula gray matter are causally associated with mental health disorders.
They explain that, instead, the posterior parietal cortex is the brain network node most likely to be causally associated with mental health conditions.
“We found that lesions to those regions were correlated with less psychiatric illness, not more, so atrophy in that cingulate and insula may be a consequence or a compensation for psychiatric illness rather than a cause of it,” corresponding author Joseph J. Taylor, MD, PhD, said in the news release.
The study authors suggest that their discovery opens an avenue of new research looking into circuit-based differences in mental health disorders. Their plan for future investigations includes using Transcranial Magnetic Stimulation (TMS) to modify the posterior parietal region of the brain. Moreover, the scientists hope to identify neuromodulation targets for people with comorbid mental health conditions.