Research from the University of Colorado Boulder and Mass General Brigham suggests that many mental health conditions may share more genetic similarities than previously understood. This groundbreaking study, which analyzed DNA from over six million individuals—more than one million of whom had a diagnosed mental health condition—could significantly alter the way these disorders are diagnosed and treated.
According to the World Health Organization, over one billion people worldwide live with mental health conditions. As mental health diagnoses often overlap, understanding the genetic connections could lead to more effective treatment strategies. “Right now, we diagnose psychiatric disorders based on what we see in the room,” said Andrew Grotzinger, assistant professor of psychology and neuroscience at the University of Colorado Boulder and the study’s corresponding author. “Many people will be diagnosed with multiple disorders. That can be hard to treat and disheartening for patients.”
Significant Findings on Genetic Patterns
The study focused on 14 psychiatric disorders and discovered that most genetic differences between those with and without these conditions could be attributed to just five broad genetic patterns. These patterns linked to 238 genetic variants affect brain development and functioning. Based on these shared genetic features, researchers categorized the disorders into five groups.
The first group consisted of disorders with compulsive traits, including anorexia nervosa, Tourette’s disorder, and obsessive-compulsive disorder. The second group encompassed internalizing conditions, such as depression, anxiety, and post-traumatic stress disorder. A third group focused on substance use disorders, while a fourth included neurodevelopmental conditions like autism and attention-deficit hyperactivity disorder. Lastly, bipolar disorder and schizophrenia formed a fifth group, revealing that approximately 70 percent of the genetic signals linked to schizophrenia were also associated with bipolar disorder. Traditionally viewed as distinct, these two conditions may actually be more genetically similar than clinicians have recognized.
“Genetically, we saw that they are more similar than they are unique,” Grotzinger explained. This insight challenges the prevailing notion that mental health conditions are largely separate illnesses, suggesting instead that many are driven by shared biological processes.
Implications for Future Diagnoses and Treatments
While the findings are promising, researchers emphasize that it is premature to revise diagnostic criteria based on this study alone. The team hopes their research will influence future updates to the Diagnostic and Statistical Manual of Mental Disorders, the globally recognized handbook for mental health professionals.
“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 stated. By identifying the shared characteristics across these disorders, researchers aim to develop treatment strategies that do not rely on multiple medications or therapy interventions.
The study also revealed specific biological pathways associated with various groups of conditions. For instance, genes that affect excitatory neurons, which transmit signals in the brain, were more active in individuals with bipolar disorder and schizophrenia. In contrast, genetic variants linked to oligodendrocytes, which maintain and protect the brain’s wiring, were more prevalent in those with depression and anxiety.
Some of these shared genetic factors may influence brain development from an early stage, even before birth, while others could have a more significant impact later in adulthood. This understanding may help explain why mental health conditions frequently overlap. A review conducted in 2018 found that more than half of individuals diagnosed with one psychiatric disorder eventually receive at least one additional diagnosis, with around 41 percent meeting the criteria for four or more disorders during their lifetime.
As this research continues to unfold, the hope is that a clearer understanding of the genetic underpinnings of mental health conditions will lead to better diagnostic practices and more effective treatments for those affected.
