Study: 14 Psychiatric Conditions Share Genetic Roots
A global study of more than 6 million people identified overlapping genes associated with five clusters of psychiatric conditions, including ADHD and autism spectrum disorder.
March 17, 2026
Some psychiatric disorders commonly co-exist because they share genes, according to a large study published in Nature that analyzed the genetic data of more than 6 million people worldwide.1
International researchers examined and traced genetic connections among 14 conditions, including ADHD, anxiety disorders, autism spectrum disorder, bipolar disorder, major depression, schizophrenia, obsessive-compulsive disorder, Tourette syndrome, post-traumatic stress disorder (PTSD), and substance use disorders, such as opioid-use disorder, cannabis-use disorder, and nicotine dependence.
They identified 428 genetic variants linked to more than one disorder, along with 101 regions, or “hot spots,” on chromosomes with high concentrations of shared genetic variants.
Using statistical modeling, the researchers determined that the 14 studied conditions clustered into five groups of conditions that shared high genetic overlap:
- compulsive disorders: obsessive-compulsive disorder, anorexia nervosa, and, to a lesser extent, Tourette disorder and anxiety disorders
- internalizing disorders: major depressive disorder, anxiety disorders, and PTSD
- neurodevelopmental disorders: ADHD, autism spectrum disorder, and, to a lesser extent, Tourette disorder
- schizophrenia and bipolar disorder
- substance use disorders: opioid use disorder, cannabis use disorder, alcohol use disorder, nicotine dependence, and, to a lesser extent, ADHD
The internalizing and substance use disorder groups demonstrated particularly high levels of shared genetic risk: Major depression, anxiety disorders, and PTSD shared about 90% of their genetic risk; schizophrenia and bipolar disorder shared roughly two-thirds of their genetic markers.
ADHD and autism spectrum disorder showed a strong genetic correlation, suggesting the two conditions share many of the same genetic risk factors. A separate study published in October 2025 found that later-diagnosed autism (after age 10) had a more significant genetic correlation to ADHD, as well as mental health conditions like depression and PTSD, compared to autism diagnosed at age 6 or younger. 2
The researchers also found that disorders with shared genetic risk often exhibit similar biological patterns in the specific genes active during development and the types of brain cells they affect. For example, genes active in oligodendrocytes (brain cells responsible for maintaining neuronal health in the central nervous system) were more strongly associated with internalizing disorders. In contrast, genes active in excitatory neurons, which stimulate other neurons, were more closely associated with schizophrenia and bipolar disorder.
About half of all people who meet the criteria for one psychiatric disorder will be diagnosed with a second or third condition in their lifetime.3, 4 According to a 2023 ADDitude survey of 1,500 readers, anxiety and depression are the two most common co-occurring conditions diagnosed alongside ADHD in adults, with co-diagnosis rates of 72% and 70%, respectively.
According to the researchers, this study represents the largest and most comprehensive analysis to date of genetic overlap among 14 psychiatric conditions. Findings from the study may help researchers and clinicians better understand the biological connections among psychiatric conditions and lead to more tailored treatments for patients.
Source
1Grotzinger, A.D., Werme, J., Peyrot, W.J. et al. (2026). Mapping the genetic landscape across 14 psychiatric disorders. Nature. https://doi.org/10.1038/s41586-025-09820-3
2Zhang, X., Grove, J., Gu, Y., Buus, C. K., Nielsen, L. K., Neufeld, S. A., Koko, M., Malawsky, D. S., Wade, E. M., Verhoef, E., Gui, A., Hegemann, L., Geschwind, D. H., Wray, N. R., Havdahl, A., Ronald, A., St Pourcain, B., Robinson, E. B., Bourgeron, T., Warrier, V. (2025). Polygenic and developmental profiles of autism differ by age at diagnosis. Nature. https://doi.org/10.1038/s41586-025-09542-6
3 Kessler, R.C. et al. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Arch. Gen. Psychiatry. https://doi.org/10.1001/archpsyc.62.6.593
4Kessler, R.C., Chiu, W.T., Demler, O. & Walters, E.E. (2005). Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication. Arch. Gen. Psychiatry. https://doi.org/10.1001/archpsyc.62.6.617
