What did the study find about the genetic links between schizophrenia and bipolar disorder?

The study found that approximately 70% of the genetic signal associated with schizophrenia was also linked to bipolar disorder, indicating substantial overlap in their genetic foundations.

Are schizophrenia and bipolar disorder the same illness?

No. They remain separate psychiatric diagnoses with different characteristic symptoms and diagnostic criteria. However, both conditions can involve psychosis, and the study found similarities in their genetic factors.

Why can schizophrenia and bipolar disorder be difficult to distinguish?

Both conditions may involve psychotic symptoms, such as hallucinations and delusions. Bipolar disorder can also include psychosis during severe mood episodes, while schizophrenia primarily affects perception of reality, thinking and interpretation of surroundings.

Could the findings change treatment for schizophrenia or bipolar disorder?

The findings could guide future research into treatments targeting biological processes shared by multiple psychiatric conditions. They do not currently change diagnostic criteria or treatment recommendations.

Schizophrenia and Bipolar Disorder Share 70% of Their Genetic Roots. Could They Be More Alike Than We Thought?

Q: Does genetic susceptibility determine whether someone develops a psychiatric disorder?

No. Genetic susceptibility is only one factor. Environmental influences, life experiences and other biological factors also contribute to the development of psychiatric disorders.

Schizophrenia and bipolar disorder are generally understood as two distinct psychiatric conditions, with different symptoms, diagnostic criteria, and treatment approaches. However, new research suggests they may have considerably more in common than previously thought, with scientists uncovering a striking overlap in their genetic foundations.

A landmark study published in Nature found that approximately 70% of the genetic signal associated with schizophrenia is also linked to bipolar disorder, raising fresh questions about how mental illnesses are classified and understood.

The findings emerged from an extensive investigation involving more than one million people diagnosed with at least one of 14 psychiatric disorders, alongside approximately five million individuals without a recorded diagnosis.

What Did Researchers Discover About the Two Conditions?

Led by researchers including Andrew Grotzinger of the University of Colorado Boulder, the international team examined genetic data to identify common and distinct biological factors associated with psychiatric conditions.

Published on 10 December 2025, the study identified five underlying genetic groupings that accounted for approximately 66% of the genetic variance across the disorders examined.

Schizophrenia and bipolar disorder formed one of these groups, with researchers finding substantial overlap in the genetic variants associated with both conditions.

The investigation also identified 238 genetic locations, known as pleiotropic loci, associated with multiple psychiatric disorders.

Other groupings included neurodevelopmental conditions such as autism and attention-deficit/hyperactivity disorder (ADHD), as well as internalising conditions such as depression, anxiety and post-traumatic stress disorder (PTSD).

Why Are Schizophrenia and Bipolar Disorder So Difficult To Distinguish?

Although they are separate diagnoses, schizophrenia and bipolar disorder can involve overlapping psychiatric symptoms, particularly psychosis.

Schizophrenia is a serious mental illness that can affect how people perceive reality, think and interpret their surroundings. Symptoms may include hallucinations, delusions, disorganised thinking and difficulties with everyday functioning.

Bipolar disorder, meanwhile, is primarily characterised by significant changes in mood, energy and activity levels. People may experience episodes of depression and mania or hypomania, depending on the type of bipolar disorder.

However, some people with bipolar disorder experience psychotic symptoms during severe mood episodes, making certain presentations difficult to distinguish from schizophrenia.

The newly identified genetic similarities could help explain why the conditions sometimes share clinical features and why some individuals experience diagnostic uncertainty.

Could the Findings Change Mental Health Treatment?

Researchers believe understanding shared genetic mechanisms could eventually help develop treatments targeting biological processes involved in multiple psychiatric conditions.

Rather than approaching every diagnosis as an entirely separate biological problem, future research could investigate therapies that address overlapping genetic vulnerabilities.

The findings may also contribute to more precise psychiatric assessments, particularly for people who experience symptoms associated with multiple conditions.

However, the discovery does not mean schizophrenia and bipolar disorder are the same illness, nor does it immediately change existing diagnostic criteria or treatment recommendations.

What Does This Mean for People at Risk?

Genetic susceptibility is only one part of the picture. Environmental influences, life experiences and other biological factors also contribute to the development of psychiatric disorders.

The researchers also acknowledged an important limitation: much of the genetic data used in the investigation came from people of European ancestry, meaning further research involving more diverse populations is necessary.

Although the findings do not yet offer a new diagnostic test or treatment, they provide compelling evidence that psychiatric conditions may be more biologically interconnected than traditional classifications suggest.

For researchers, understanding those connections could eventually change how mental illnesses are investigated, diagnosed and treated.