Different Mental Health Conditions Share Similar Genetics, Study Says

Key TakeawaysDifferent mental health conditions might be driven by similar geneticsResearchers created five different genetic categories containing the 14 most prominent mental health conditionsMost surprising, schizophrenia and bipolar disorder share 70% of genetics.FRIDAY, Dec. 19, 2025 (HealthDay News) — Psychiatric conditions as varied as schizophrenia and bipolar disorder might be driven by very similar genetic underpinnings, a new study says. Mental health problems can be sorted into five general genetic categories, each with a shared “genetic architecture” driving people’s illness, according to results published in the journal Nature.“Right now, we diagnose psychiatric disorders based on what we see in the room, and many people will be diagnosed with multiple disorders. That can be hard to treat and disheartening for patients,” lead researcher Andrew Grotzinger, an assistant professor of psychology and neuroscience at the University of Colorado-Boulder, said in a news release.“This work provides the best evidence yet that there may be things that we are currently giving different names to that are actually driven by the same biological processes,” he said.The results might explain why more than half of people with one psychiatric disorder will be diagnosed with a second or third in their lifetime, researchers said. About 41% will meet the criteria for four or more.For the study, researchers examined DNA data from more than 1 million people diagnosed with one of 14 mental illnesses. They compared that to data for 5 million people with no mental health problems.Results showed the majority of genetic differences between people with a particular mental disorder and those without it can be boiled down to five general categories involving 238 genetic variants:Disorders with compulsive features like anorexia, Tourette disorder and obsessive-compulsive disorder“Internalizing” disorders like depression, anxiety and post-traumatic stress disorderSubstance use disordersNeurodevelopmental conditions like autism and attention deficit/hyperactivity disorderBipolar disorder and schizophreniaThis last is notable, given that the field of psychology has historically viewed bipolar disorder and schizophrenia as very different, researchers said. Doctors typically will not diagnose an individual with both.But 70% of the genetic signal associated with schizophrenia is also associated with bipolar disorder, the study said.“Genetically, we saw that they are more similar than they are unique,” said Grotzinger.Results also indicate how these genetics might affect a person’s biology to increase their risk of different mental conditions.For example, genes that influence excitatory neurons — brain cells involved in transmitting signals across other neurons — tend to be over-expressed in both bipolar disorder and schizophrenia.Likewise, genetic variants that control specialized cells called oligodendrocytes were more common among people with internalizing disorders like depression and anxiety. Those cells help maintain and protect the brain’s wiring infrastructure.“These findings provide valuable clues for advancing our understanding and treatment of mental illness with greater precision,” senior researcher Dr. Jordan Smoller said in a news release. He’s director of the Center for Precision Psychiatry at Mass General Brigham in Boston.The results suggest some shared genetic factors might play a role in brain development as early as in the womb, while others might have a greater influence later in a person’s adult life, researchers said.These insights could help doctors better diagnose mental conditions and lead to new, more precise treatments, researchers said.“By identifying what is shared across these disorders, we can hopefully come up with ways to target them in a different way that doesn’t require four separate pills or four separate psychotherapy interventions,” Grotzinger said.More informationStanford Medicine has more on genetics and mental health.SOURCE: University of Colorado-Boulder, news release, Dec. 16, 2025 .What This Means For YouDifferent mental health conditions might have similar genetic underpinnings, researchers say..Sign up for our weekly HealthDay newsletter