A new study published in Translational Psychiatry is drawing attention to a question at the intersection of mental health, genetics and preventive medicine: why are people with a higher inherited susceptibility to severe mental illness also more likely to develop physical diseases during their lives? The research, led by U. Isayeva, S. Guloksuz and B.D. Lin and colleagues, examines how genetic liability and everyday lifestyle factors may be connected to the risk of developing new somatic illnesses—medical conditions affecting the body rather than the mind.
The study focuses on severe mental illness, a term generally used for conditions such as schizophrenia, bipolar disorder and other psychiatric disorders that can substantially affect functioning, long-term health and life expectancy. Although these disorders are diagnosed through psychological and behavioral symptoms, their consequences are not limited to the brain. People living with severe mental illness frequently experience higher rates of cardiovascular disease, metabolic disorders, respiratory problems and other chronic physical conditions. The new research investigates whether this pattern can be partly explained by inherited biology, lifestyle, or an interaction between the two.
To explore genetic vulnerability, researchers use a concept known as genetic liability. This is commonly estimated through a polygenic risk score, a statistical measure that combines the effects of many genetic variants, each of which may contribute only a very small amount to disease susceptibility. Unlike a single-gene test, a polygenic score does not predict with certainty whether an individual will develop a psychiatric disorder. Instead, it places people along a spectrum of inherited risk and allows scientists to examine whether that risk is associated with other health outcomes.
The study also considers lifestyle, a potentially modifiable component of long-term health. Lifestyle research typically includes factors such as smoking, alcohol consumption, physical activity, diet, sleep and body weight. These behaviors can influence the immune system, blood pressure, glucose regulation and inflammation—biological pathways that may contribute to both psychiatric and physical illness. By examining lifestyle alongside genetic liability, the researchers aim to move beyond explanations that treat mental illness or somatic disease as the result of a single cause.
This combined approach is important because genetic susceptibility and behavior are not independent forces operating in separate compartments. Genetic factors may influence traits related to impulsivity, appetite, sleep, stress response or sensitivity to substances. At the same time, living with severe mental illness can make healthy routines more difficult to establish. Symptoms, medication side effects, poverty, stigma, social isolation and limited access to medical care may all affect physical health behaviors and the ability to receive preventive treatment.
A major scientific challenge is distinguishing correlation from causation. If people with greater genetic liability for severe mental illness show higher rates of physical disease, that association does not automatically mean the genetic variants directly cause those illnesses. The relationship could reflect shared biological pathways, medication exposure, environmental stress, healthcare disparities or lifestyle patterns. Researchers therefore need statistical models that account for multiple potential influences and carefully define when a physical disease first appears, a measure known as incident illness.
The focus on incident somatic illnesses is especially valuable for prevention. Studying diseases that arise after the beginning of observation can help researchers identify risk factors that precede diagnosis, rather than simply describing health problems that already exist. This distinction may reveal opportunities for earlier screening, personalized counseling and coordinated care. For example, people identified as having elevated cardiometabolic risk could potentially receive more frequent monitoring of blood pressure, cholesterol and blood glucose, alongside psychiatric treatment.
The findings also speak to a broader shift in medicine. Mental and physical health are increasingly understood as parts of one interconnected biological system rather than as separate domains. Chronic inflammation, hormonal regulation, sleep disruption and autonomic nervous-system activity can affect both brain function and the rest of the body. However, genetic-risk research must be interpreted carefully. A polygenic score reflects probabilities derived from a specific population and research dataset; it is not a diagnosis, and its accuracy can vary across ancestral groups because many genetic studies have historically relied heavily on people of European descent.
The study by Isayeva, Guloksuz, Lin and colleagues therefore contributes to a growing effort to understand why severe mental illness is associated with poorer physical health and how that gap might be reduced. Its central message is not that genes determine a person’s future, nor that lifestyle alone explains complex disease. Rather, the research examines how inherited vulnerability and modifiable behavior may combine over time. That framework could help transform psychiatric care from a narrow focus on symptoms into a more complete model of prevention—one that treats the brain and body as inseparable parts of human health.
Subject of Research: Associations among lifestyle factors, genetic liability for severe mental illness and the risk of developing somatic illnesses.
Article Title: Associations between lifestyle, genetic liability for severe mental illness and risk of incident somatic illnesses.
Article References: Isayeva, U., Guloksuz, S., Lin, B.D. et al. “Associations between lifestyle, genetic liability for severe mental illness and risk of incident somatic illnesses.” Translational Psychiatry (2026).
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41398-026-04332-8
Keywords: severe mental illness, genetic liability, polygenic risk, lifestyle, somatic illnesses, physical health, psychiatric disorders, preventive medicine, Translational Psychiatry
