The study, conducted by the Psychiatric Genomics Consortium Cross-Disorder Working Group and published in Nature, analysed DNA from more than six million people worldwide. This makes it the most comprehensive genetic study of mental health to date.
Five main genetic groups
The analyses revealed five major genetic groups that link many psychiatric disorders. For example, anorexia nervosa, OCD and Tourette's syndrome were found to share some of the same genetic characteristics. Depression, anxiety and PTSD were also found to be strongly genetically related, as were schizophrenia and bipolar disorder.
In addition, autism and ADHD together formed a distinct genetic group, while substance use - such as alcohol or drug addiction - formed its own cluster. This classification shows that disorders we traditionally think of as separate often overlap biologically.
Key genetic pathways in the brain
The researchers found 238 genetic variants clearly associated with the five groups. Those variants point to specific processes in the brain. For example, in schizophrenia and bipolar disorder, genes in excitatory neurons mainly play a role. Depression and anxiety, on the other hand, more often involve genes active in oligodendrocytes, cells that help in signal conduction in the brain.
What does this mean for society?
The results underline that mental disorders are often not unrelated: they share a biological foundation. That insight can have an impact in several ways:
- Better diagnostics: By understanding which disorders are genetically related, doctors and researchers can work towards a classification that is more in line with biology than the current symptomatic classification.
- More targeted treatments: The genetic pathways identified offer new entry points for future drugs and therapies, especially for people who have multiple mental disorders at the same time.
- Reduced stigma: By highlighting that many mental disorders stem from shared biological factors, the research may contribute to greater understanding and reduced guilt among patients and those around them.
The researchers, including neuroscientist Christiaan de Leeuw of Vrije Universiteit Amsterdam, call their work "a step towards a biologically informed map of mental disorders" a map that in the future could help in better prevention, faster recognition and more effective treatment of mental problems.