A massive genetic analysis of more than 6 million people is revealing new clues about why mental health disorders frequently overlap.
An international group of scientists has uncovered new evidence explaining why many mental health disorders tend to occur together. By examining genetic data from more than 6 million people, the researchers explored how over a dozen psychiatric conditions may be connected, including depression, anxiety, schizophrenia, bipolar disorder, ADHD, PTSD, and substance use disorders.
The study, published in Nature, was co-authored by Drs. John Hettema and Brad Verhulst of the Texas A&M University Department of Psychiatry and Behavioral Sciences in the Naresh K. Vashisht College of Medicine.
Because of its massive scale, the research offers one of the clearest views so far of how genetic risk is shared across different psychiatric conditions. The team analyzed DNA data for 14 childhood and adult onset disorders. The dataset included more than 1 million people diagnosed with a psychiatric disorder and about 5 million people with none of the studied conditions.
Genetic links between mental health disorders
“Genetic risk” refers to the likelihood of developing a disease or health condition based on inherited variations in DNA.
The researchers found that the psychiatric disorders in the study share a substantial amount of genetic risk. These risks formed five broad categories:
Compulsive disorders (like OCD and anorexia)
Schizophrenia and bipolar disorder
Neurodevelopmental disorders (such as autism and ADHD)
Internalizing disorders (depression, anxiety, PTSD)
Substance use disorders
These results suggest that the same genetic influences often affect multiple disorders. This overlap may help explain why people frequently experience more than one mental health condition.
