Many vastly different mental-health disorders, ranging from schizophrenia to depression, stem from the same brain regions, according to a new study.
In the study, researchers compared the results of hundreds of brain imaging studies covering six major psychiatric disorders. They found that most of the disorders were linked to gray matter loss in a network of three brain regions involved in higher cognitive functions, such as self-control and certain types of memory.
Given these similarities in brain structure, treatments for one mental-health condition may be effective in others, the researchers said. [5 Controversial Mental Health Treatments]
For the past four decades, psychiatrists have diagnosed mental disorders according to a checklist of symptoms specified in the Diagnostic and Statistical Manual of Mental Disorders (DSM), said Dr. Amit Etkin, a psychiatrist and neuroscientist at Stanford University and senior author of the study, published today (Feb. 4) in the Journal of the American Medical Association Psychiatry.
"We wanted to test a very simple question that simply hadn't been asked" — whether common psychiatric disorders have a common structure in the brain, Etkin told Live Science.
To find out, Etkin and his colleagues turned to the medical literature. They sifted through nearly 200 structural brain imaging studies that involved more than 7,000 people with schizophrenia, bipolar disorder, depression, addiction, obsessive-compulsive disorder or anxiety, as well as some 8,500 healthy individuals.
When the researchers compared the findings from different psychiatric disorders, they found that all of them showed loss of gray matter— tissue that contains the bodies of nerve cells — in three regions deep in the brain: the dorsal anterior cingulate cortex (dACC), the right insula and the left insula. This network of areas is linked to executive functioning, which Etkin defined as the things that allow a person to function in life — for instance, hold down a job, maintain a relationship, not act on impulses, resist distractions and so on.
The fact that many psychiatric disorders share a common structural root will make it easier to apply therapies for one disorder to another, Etkin said. For example, computer cognitive training has shown some promise in treating schizophrenia, and may also be useful in treating other disorders, he said.
"I think clinicians tend to think this way already, but we had not had the connection to the science," Etkin said. "As a clinician, I see commonalities between patients [with different diagnoses], but until I did this study, I was unable to understand what they were and how they operate."
For the most part, the researchers found brain similarities among the different disorders. However, they did find some differences. For example, schizophrenia differed from other mental-health disorders in the amount of gray-matter loss, and depression also involved shrinkage of the amygdala and hippocampus, brain regions involved in emotion and memory, respectively, the researchers found.
In the future, Etkin plans to investigate whether brain activity, in addition to brain structure, shows similarities across the different disorders. In addition, his team is developing tools to apply noninvasive brain stimulation to the brain regions studied, to see whether zapping them could help treat people with these conditions.
Such treatments may be available "not off in the imaginary future, but in the next couple of years," Etkin said.