Mental disorders, such as obsessive-compulsive disorder (OCD) and bipolar disorder, can strongly affect daily life. They are usually caused by a mix of genetic risk and environmental factors like stress or adverse life events. But understanding how these influences work together has been a major challenge.

Epigenetics helps explain this link. It refers to chemical changes that affect how genes work, without changing the DNA sequence itself.

One key mechanism is DNA methylation — small chemical “marks” that can be influenced by both our genes and our experiences, especially early in life.

Clear differences in patients

In two new studies, researchers from the University of Bergen compared DNA methylation patterns in people with either OCD or bipolar disorder to those of healthy controls. The studies have been published in Biological Psychiatry and Lancet eBiomedicine, respectively.

They found clear differences between the groups.

Many of these changes were linked to genes involved the immune system, suggesting that immune processes may play an important role in both disorders. Other genes implicated were relevant to neuronal functions and were relevant for the respective disorders.

Importantly, some of the DNA changes overlapped with known genetic risk factors, which may help explain how genetic risk may increase the disease liability. Others were independent of genetics, likely reflecting the impact of environmental factors such as stress.

In bipolar disorder, researchers showed that a global “methylation score” could improve prediction models when added to genetic information—an important step toward precision psychiatry.

A growing research tool

Together, the findings show that epigenetic research is becoming a powerful addition to genetic studies in psychiatry.

While larger studies are still needed, international collaboration is already making it possible to uncover new biological insights, and move closer to more tailored treatments for mental disorders.

Links to the publications:
www.biologicalpsychiatryjournal.com/article/S0006-3223(26)01133-9/fulltext

https://www.sciencedirect.com/science/article/pii/S2352396426001660