The analysis of data on the DNA of more than six million people, among whom over a million had at least one mental disorder, showed that there are common genetic patterns that can explain many disorders.
According to the World Health Organization, more than a billion people live with mental disorders. Andrew Grotzinger, an assistant professor of psychology and neuroscience at the University of Colorado, noted that modern diagnostic practices are based on clinical manifestations, which complicates the treatment of patients with multiple diagnoses.
The study examined 14 different psychiatric disorders. Researchers found that most genetic differences between people with these disorders can be explained by just five major genetic patterns associated with 238 genetic variants that affect brain function and development.
The first category included disorders with compulsive symptoms, such as anorexia nervosa, Tourette syndrome, and obsessive-compulsive disorder. The second group encompasses internal disorders, such as depression and anxiety disorders. The third includes disorders related to substance use, while the fourth group includes neurodevelopmental disorders, such as autism and ADHD. Finally, bipolar disorder and schizophrenia form the fifth category. The study showed that about 70% of the genetic factors associated with schizophrenia are also related to bipolar disorder.
Grotzinger noted that from a genetic standpoint, these two conditions have more in common than differences, which calls into question traditional approaches to their diagnosis.
Potential Implications for Patients
The results of the study, published in the journal Nature, challenge the notion that mental disorders are isolated diseases. Instead, the research suggests that many of them share common biological processes.
However, scientists caution against hasty changes in diagnostic approaches. The team hopes that the findings will serve as a foundation for future updates to the Diagnostic and Statistical Manual of Mental Disorders (DSM), used by professionals worldwide.
Grotzinger added that this work represents the most compelling evidence that disorders with different names may be caused by similar biological processes. Identifying common features could lead to the development of new treatment strategies that are more integrated and effective.
The study also highlighted important biological pathways associated with different groups of disorders. For example, genes responsible for neuron excitation were more active in people with bipolar disorder and schizophrenia. Patients with depression and anxiety disorders exhibited genetic variants associated with oligodendrocytes, cells that support brain function.
Some of the common genetic factors, it turned out, may influence brain development even before birth, while others begin to act at a later age. This may explain why mental disorders often overlap.
According to a review conducted in 2018, more than half of people with one psychiatric diagnosis subsequently receive at least one more, and about 41% meet the criteria for four or more diagnoses during their lifetime.
