Study Reveals Shared Genetic Roots Across Multiple Psychiatric Disorders

Psychiatric disorders can share common genetic influences, new research suggests, potentially explaining why many mental health conditions frequently occur together. The groundbreaking study, published in Nature and led by researchers at Texas A&M University, has identified specific DNA patterns that may underlie multiple mental disorders.

The research team analyzed DNA data from more than one million individuals diagnosed with any of 14 childhood and adult-onset psychiatric disorders, comparing it against genetic information from five million people without these conditions. This extensive analysis represents one of the largest genomic studies of mental health ever conducted.

Researchers organized the disorders into five distinct groups: compulsive disorders (including OCD and anorexia), schizophrenia and bipolar disorder, neurodevelopmental disorders (such as autism and ADHD), internalizing disorders (depression, anxiety, PTSD), and substance-use disorders.

“By uncovering shared genetic roots, we can start thinking about treatments that target multiple disorders instead of treating each one in isolation,” explained co-author John Hettema, M.D., Ph.D. This perspective represents a significant shift from the traditional approach of addressing mental health conditions as entirely separate entities.

Each pattern identified in the study is linked to 238 small genetic differences that influence brain function and development. These variations offer valuable insights into why certain conditions overlap while others remain distinct. Notably, some traits—including suicidal thoughts and loneliness—showed genetic connections across all five disorder groups.

The specific biological mechanisms varied between disorder groups. For the schizophrenia-bipolar group, the strongest genetic associations appeared in brain cells that send “go” signals and facilitate communication between different regions. In contrast, internalizing disorders like depression and anxiety showed stronger links to cells that help brain signals travel faster.

To identify these patterns, scientists employed genome-wide association studies (GWAS), which compare DNA from large populations with and without specific conditions. These studies scan millions of common genetic markers to detect subtle differences more prevalent in people with particular disorders. The team then used genetic correlation techniques to determine how much genetic risk overlapped between different conditions.

Dr. Daniel Amen, a psychiatrist and founder of Amen Clinics in California who wasn’t involved in the study, called the findings confirmation that “mental health disorders share deep genetic connections, especially involving brain development and synaptic function.”

“What this means is that conditions like depression, bipolar disorder, schizophrenia and ADHD aren’t isolated silos—they’re part of overlapping biological systems that start in the brain, often as early as in utero,” Amen noted. He emphasized that this research adds “another layer of biological insight” that could eventually lead to screening tools identifying vulnerabilities in childhood, allowing for earlier interventions.

The researchers were careful to point out that genetics alone don’t determine whether someone will develop these disorders. Rather, genetic traits “set the stage” by increasing or decreasing inherent risk, which can then be triggered by environmental factors like stress, trauma, or other life experiences.

“Just because a gene is linked to a disorder doesn’t mean it causes it—or that changing it changes the outcome,” Amen cautioned. “The environment still matters. Genetics load the gun, but stress, trauma, diet, infections, toxins and head injuries pull the trigger.”

This research may ultimately transform the approach to psychiatric diagnosis and treatment. Rather than relying solely on observable symptoms, future mental health care could incorporate genetic profiles alongside other biological markers to develop more personalized treatment strategies that address the underlying shared mechanisms of related disorders.

“If we get this right—and combine genetic research with brain imaging, digital phenotyping and clinical neuroscience—the entire landscape of mental health care will change,” Amen predicted. “We’ll no longer be diagnosing based on symptoms alone. We’ll be diagnosing based on objective, biological data.”