Five genetic groups underlie 14 mental disosrders - New data support suggest new classifications and treatment possibilities

By: Tom Cloyd - 4 minute read

(Reviewed: 2026-01-17:0851 Pacific Time (USA))

Five trees in a forest

Photo by Dibbendu Koley on Unsplash

From our genes and our personal history come all our physical and mental characteristics. Biologists and physicians have long known this, but how this applies to mental disorders has never been at all clear. We know more about the genetic basis of cancer than we do of mental illness.1 This is now changing.

In biology until recent times, animals and plants as well as bacteria were classified on the basis of appearance and behavior. There was nothing else to use. The same approach has long been used with mental illness. There are major drawbacks to this approach.

Judging from appearance alone, it would hardly seem rational to think that a chihuahua and a Great Dane are the same animal, but they are in fact the same species. Genetics makes this clear. Could we be approaching this sort of reconceptualization with some mental illnesses? It appears increasingly likely.

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The international Psychiatric Genomics Consortium (PGC) has reported a major new study of a very large number of people, focusing on 14 psychiatric disorders.2 It found that the disorders group into five categories on the basis of 238 genetic variations found in diagnosed individuals but not in others1 This implies a fundamental genetic basis for disorders which to this point have been seen as fundamentally different when viewed solely in terms of people’s experiences and behaviors.

This finding was not unexpected, as earlier studies have indicated that genetic similarities exist between a number of disorders usually seen as distinct. This new study details many more genetic similarities, not all of which are negative. A striking example of this is that “the genetic overlap between schizophrenia and bipolar disorder is also associated with traits that can support academic success, such as creativity and persistence.”3

Using traditional psychiatric diagnostic categories to characterize the individuals found to have genetic similarities, here are the five groups found by this large-scale genetic study:13

  • Compulsive disorders: anorexia nervous, Tourette’s syndrome and obsessive-compulsive disorder
  • Neurodevelopment disorders: autism, attention-deficit/hyperactivity disorder
  • Internalizing disorders: anxiety, depression, PTSD
  • Substance use disorders: Alcohol, cannabis, nicotine, and opioid dependence
  • Schizophrenia and bipolar disorder

We already know that some apparently distinct disorders can respond to the same treatment. “Some antidepressants seem to work, not only for depression, but also for anxiety and post-traumatic stress disorder.”1 Knowing that disorders share a common genetic variation pattern can “offer new entry points for developing treatments that target risk pathways common to frequently co-occurring conditions.”4 It is possible that new treatments may be found that work well for disorders now known to be genetically similar.

There is an increasing trend in medication to individualize treatments. Genetic distinctions already do this for cancer, for example. But precision psychiatry is not yet possible, as the genetic distinctions that can be made cannot yet be related precisely enough to specific mental disorders and their variations. However, the increase in precision offered by this new genetic study clearly moves the hope for precision psychiatry in the right direction.5

How we think about mental disorders is likely to be affected by these new genetic findings, for they provide more “support to the notion that current psychiatric diagnoses do not represent distinct pathogenic entities, which may inform ongoing attempts to reconceptualize psychiatric nosology” (classification schemes).5

The experience those affected by mental disorders is also likely to change if our way of classifying disorders is simplified. Instead of being hit with 3 or more distinct diagnoses, it may make more sense to use but one, followed by a similar simplification in the treatment offered.1. This would lighten the burden of the affected in several ways.

Genetics aren’t fate. “A person can have a genetic predisposition for a given disorder but not ultimately develop it unless they encounter certain adverse events, whether trauma or environmental hazards.”3

In addition, the genetic variations found do not account for all the genetic risk associated with these 14 disorders. About a third remains unaccounted for.4

The study subjects were all of European ancestry, which limits the scope of generalization the study supports. Efforts are underway to expand the genetic scope of the data.1

Andreassen, O. A., Hindley, G. F. L., Frei, O., & Smeland, O. B. (2023). New insights from the last decade of research in psychiatric genetics: Discoveries, challenges and clinical implications. World Psychiatry, 22(1), 4–24. https://doi.org/10.1002/wps.21034

Brincat. C. (2025, December 15). 5 genetic “signatures” underpin a range of psychiatric conditions. Live Science. https://www.livescience.com/health/genetics/5-genetic-signatures-underpin-a-range-of-psychiatric-conditions

Grotzinger, A. D., Werme, J., Peyrot, W. J., Frei, O., de Leeuw, C., Bicks, L. K., Guo, Q., Margolis, M. P., Coombes, B. J., Batzler, A., Pazdernik, V., Biernacka, J. M., Andreassen, O. A., Anttila, V., Børglum, A. D., Breen, G., Cai, N., Demontis, D., Edenberg, H. J., … Smoller, J. W. (2026). Mapping the genetic landscape across 14 psychiatric disorders. Nature, 649(8096), 406–415. https://doi.org/10.1038/s41586-025-09820-3

Johnson, M. (2026, January 16). Mental illnesses share genetic similarities, suggesting need for fewer pills. Washington Post. https://www.washingtonpost.com/health/2026/01/01/psychiatric-disorders-genetic-bipolar-schizophrenia/

University of Oslo, Faculty of Medicine. (2025, December 11). Shared genetic roots of 14 psychiatric disorders revealed. News-Medical Net. https://www.news-medical.net/news/20251211/Shared-genetic-roots-of-14-psychiatric-disorders-revealed.aspx

  1. Johnson, M. (2026, January 16) ^ ^2 ^3 ^4 ^5 ^6

  2. Grotzinger, A. D., et al. (2026) ^

  3. Brincat. C. (2025, December 15). ^ ^2 ^3

  4. University of Oslo, Faculty of Medicine. (2025, December 11) ^ ^2

  5. Andreassen, O. A., et. al. (2023). ^ ^2

 

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