In a new analysis, a German research team looked at data from magnetic resonance imaging (MRI) studies and discovered that four different neuropsychiatric conditions — major depression, bipolar disorder, schizophrenia, and obsessive-compulsive disorder (OCD) — share brain structural abnormalities. They also found brain signatures that were unique to these individual conditions.

On the other hand, the researchers found that attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) did not share brain structural signatures with any other disorders.

The findings are published in the journal Biological Psychiatry.

“We found that 4 major psychiatric disorders — major depression, bipolar disorder, schizophrenia, and obsessive-compulsive disorder — show a surprisingly high level of similarity in their brain structural abnormalities,” said co-first author Nils Opel, MD. from the University of Münster, Germany,

The shared brain areas showing structural abnormalities were mainly in cortical areas associated with cognitive processing, memory and self-awareness.

On the other hand, Opel added, “we were able to identify regional abnormalities with high specificity for certain disorders.” Interestingly, these distinct structural differences sometimes appeared in the same area for two disorders, but in opposite directions from the norm.

Interestingly, attention-deficit/ hyperactivity disorder and autism spectrum disorder did not share brain structural signatures with any other disorders. This may be due to the fact that these disorders are considered developmental diseases with distinct underlying mechanisms separate from the other psychiatric conditions, which have more in common.

The researchers do not yet understand the mechanisms behind the shared structural elements, but a growing body of evidence reveals that these psychiatric disorders also share common genetic as well as environmental influences, which might underlie the current findings.

For the study, the research team analyzed data collected as part of the effort by an international research consortium called ENIGMA, for “Enhancing Neuro Imaging Genetics through Meta Analysis,” which uses genetic and imaging studies to understand brain diseases. The 11 multi-center studies collected brain-imaging data from more than 12,000 people.

“Our understanding arising from brain imaging studies of the biology of neuropsychiatric disorders is changing,” said John H. Krystal, MD, Editor of Biological Psychiatry. “Initially, we focused on the individual properties of particular patient groups. Then, some imaging studies suggested that neuropsychiatric disorders were dimensionally related. This new study affirms the dimensional relationship among some disorders, but suggests that some categorical distinctions may exist at the biological level.”

The current finding of regional abnormalities specific to individual conditions “could help shift the focus of future psychiatric and neuroscientific research on brain regions that appear to be central to disorder-specific biological processes and hence might facilitate the discovery of mechanisms underlying the development of specific psychiatric disorders,” said Opel.

Opel (together with Janik Goltermann, MSc) said of the work, “the identification of shared and disorder-specific brain structural signatures might enhance the future development of biologically informed diagnostic applications in psychiatry.”

The study was led by Bernhard T. Baune, MD, PhD, and Udo Dannlowski, MD, PhD, from the University of Münster in Germany.

The new article, titled “Cross-Disorder Analysis of Brain Structural Abnormalities in Six Major Psychiatric Disorders – A Secondary Analysis of Mega- and Meta-Analytical Findings from the ENIGMA Consortium,” appears in the journal Biological Psychiatry, published by Elsevier.

Source: Elsevier