A new review finds that psychiatric disorders are characterized by common alterations of connectivity among three core brain networks involved with cognition. The meta-analysis discovered the network alterations were localized in brain regions underlying general cognitive performance.
The finding suggests traditional imaging studies and biomarkers reflect symptom-related issues and not so much the underlying disease pathology.
Researchers explain that although psychiatric illnesses are considered to be distinct disorders, cognitive dysfunction appears in most of them. This overlap of symptoms across psychiatric disorders has been a major challenge to precisely categorize patients.
The new study suggests that the alterations in brain networks that influence cognitive dysfunction are present in multiple psychiatric disorders. Investigators performed a meta-analysis of 242 functional brain imaging studies in people with a variety of psychiatric disorders. They discovered alterations in functional connectivity among three large-scale networks considered to be particularly important for complex cognition.
The review appears in the journal Biological Psychiatry.
The brain systems involved with cognitive impairment include the default mode network, the frontoparietal network, and the salience network. Furthermore, analysis of 363 structural brain imaging studies revealed reduced gray matter associated with the altered networks, tightly linking structural and functional alterations.
Importantly, the study provides the first evidence from a meta-analysis of common functional connectivity alterations in neurocognitive networks across psychiatric disorders. “This new knowledge calls for studying brain-based diagnostic biomarkers of psychiatric disorders that are beyond traditional diagnostic boundaries,” said senior author Yong He, PhD, Beijing Normal University, China.
Although enormous progress has been made in characterizing the neural correlates of diagnoses and symptoms over the past 25 years, neuroimaging biomarkers have yet to contribute to the psychiatric diagnostic process.
“Dr. He and colleagues provide an important clue as to why neuroimaging diagnostic biomarkers have made limited progress,” said John Krystal, MD, Editor of Biological Psychiatry.
“This finding pushes us to rethink the potential role of neuroimaging in the diagnostic process.”
The shared neurocognitive network alterations suggest that neuroimaging may be providing a measure of symptom-related pathology not directly related to the disease process.
Therefore, this could pose a problem, as the study of psychiatric disorders–which are defined by collections of symptoms–is primarily limited to the study of behaviors.