A new genetic study of over one million people has found that many psychiatric disorders share common biological underpinnings, challenging traditional diagnostic categories, according to research published today in Nature. The analysis indicates that conditions such as depression, anxiety, schizophrenia, and autism often overlap at the genetic level, suggesting that they are less distinct than previously thought.
Researchers identified 14 major psychiatric disorders and grouped them into five categories, each with shared genetic risk factors. The neurodevelopmental category, for instance, includes attention deficit hyperactivity disorder (ADHD) and autism—conditions that are traditionally treated as separate. Other categories include a schizophrenia/bipolar cluster, an internalizing group (depression, anxiety, PTSD), a compulsive category (OCD and anorexia), and a substance-use group encompassing alcohol and nicotine dependence.
“Many psychiatric conditions are ultimately more overlapping than they are distinct, which should offer patients hope,” said study co-author Andrew Grotzinger, a psychiatric geneticist at the University of Colorado Boulder. “You can see the despair on someone’s face [when] you give them five different labels as opposed to one label.”
The researchers also identified 238 genomic regions associated with at least one of the shared categories. For example, a region on chromosome 11 influences dopamine signalling and increases risk for eight separate disorders. Additionally, they uncovered a general psychopathology factor, or p-factor, representing a shared genetic vulnerability across nearly all psychiatric conditions. Many of these genes are involved in fetal brain development, suggesting that susceptibility to psychiatric disorders is rooted in early life.
The study further found that different categories are linked to distinct brain cell types. The schizophrenia/bipolar cluster is associated with excitatory neurons that transmit electrical signals, while internalizing disorders relate to oligodendrocytes, cells that support and insulate neurons.
These findings may transform how mental-health disorders are classified, shifting from symptom-based manuals to biology-based frameworks, said clinical psychologist Terrie Moffitt of Duke University. Clinicians could use this knowledge to help patients with one disorder reduce their risk for others, emphasizing strategies such as stress management, while researchers could develop treatments targeting multiple conditions simultaneously.
The work, published in Nature, provides compelling evidence that the high prevalence of co-occurring psychiatric disorders reflects shared genetic foundations rather than coincidence, marking a major step toward a more biologically grounded understanding of mental health.
