A significant genetic study has revealed that various mental health conditions may share more biological similarities than previously thought. Conducted by researchers from the University of Colorado Boulder and Mass General Brigham, the findings could transform the diagnosis and treatment of mental health issues, particularly for individuals living with multiple diagnoses.
The study analyzed DNA from over six million people, including more than one million diagnosed with at least one mental health condition. According to the World Health Organization, over a billion individuals globally live with these disorders.
New Insights into Mental Health Diagnostics
Current diagnostic practices often rely on observable symptoms, leading to many individuals receiving multiple diagnoses. “Right now, we diagnose psychiatric disorders based on what we see in the room, and many people will be diagnosed with multiple disorders. That can be hard to treat and disheartening for patients,” said Andrew Grotzinger, assistant professor of psychology and neuroscience at the University of Colorado Boulder and corresponding author of the study.
The research team focused on 14 psychiatric disorders and discovered that most genetic differences between affected and unaffected individuals could be explained by five broad genetic patterns. These patterns are linked to 238 genetic variants that influence brain development and function.
The researchers categorized the conditions into five groups, including disorders with compulsive traits like anorexia nervosa, Tourette’s disorder, and obsessive-compulsive disorder. Other groups encompassed internalizing conditions such as depression, anxiety, and post-traumatic stress disorder; substance use disorders; neurodevelopmental conditions like autism and attention-deficit hyperactivity disorder; and a final group consisting of bipolar disorder and schizophrenia.
Remarkably, around 70 percent of the genetic signal associated with schizophrenia was also found to be linked to bipolar disorder, despite these conditions historically being viewed as distinct. “Genetically, we saw that they are more similar than they are unique,” stated Grotzinger.
Implications for Future Mental Health Treatments
The results, published in the journal Nature, challenge the long-standing perspective that mental health disorders are primarily separate illnesses. Instead, the study indicates many are driven by shared biological processes. Nonetheless, researchers caution against immediate changes in diagnostic criteria, hoping their findings will inform future revisions of the Diagnostic and Statistical Manual of Mental Disorders, the authoritative guide for mental health professionals worldwide.
“This work provides the best evidence yet that there may be things that we are currently giving different names to that are actually driven by the same biological processes,” Grotzinger noted. The goal is to develop treatment strategies that do not require multiple medications or therapy interventions for overlapping conditions.
The study also identified specific biological pathways associated with different groups of conditions. For instance, genes affecting excitatory neurons, which transmit signals in the brain, were more active in individuals with bipolar disorder and schizophrenia. Meanwhile, genetic variants linked to oligodendrocytes, which maintain and protect the brain’s wiring, were more prevalent in those with depression and anxiety.
Some shared genetic factors seem to influence brain development early in life, even before birth, while others may become more significant later in adulthood. This insight could help clarify why mental health conditions frequently co-occur.
A 2018 review found that over half of those diagnosed with one psychiatric disorder later receive additional diagnoses, with about 41 percent meeting the criteria for four or more throughout their lives. As research continues to uncover the genetic underpinnings of mental health conditions, the potential for more effective, streamlined treatment approaches grows increasingly promising.
