Observational study finds adults with severe mental illness die 15-20 years earlier — Evidence Review

Adults with severe mental illness in England die 15–20 years earlier than the general population, with nearly five times the risk of dying before age 75 from largely preventable physical illnesses, according to a new analysis by Rethink Mental Illness. These findings are consistent with a broad scientific literature demonstrating significantly increased mortality and reduced life expectancy in people with severe mental illness worldwide.

• Large-scale meta-analyses and cohort studies across multiple countries consistently show that severe mental illness is associated with a reduction in life expectancy of 10–20 years, with mortality rates for physical diseases such as cardiovascular, respiratory, and liver conditions two to three times higher than in the general population 1 2 3 4 5 11 12 13 14.
• The new study's detailed breakdown of cause-specific mortality (e.g., elevated risks for liver disease, respiratory illness, cardiovascular disease, and cancer) is strongly supported by prior research, which also highlights suicide and external causes as major contributors to premature death in this population 3 4 11 12 13 14.
• Existing research also emphasizes the role of modifiable risk factors (such as smoking, obesity, and substance use), healthcare disparities, and "diagnostic overshadowing"—where physical symptoms are misattributed to mental illness—mirroring the drivers identified in the Rethink analysis 12 13 14 15.

Study Overview and Key Findings

This new study arrives at a critical time when health inequalities and the intersection of physical and mental health are under heightened policy scrutiny. Using comprehensive NHS data, Rethink Mental Illness analyzed mortality among adults in England referred to specialist secondary mental health services, focusing on deaths before age 75 due to physical illnesses and suicide. The study quantifies not only the overall reduction in life expectancy but also the disproportionate risk of death from specific diseases and the contribution of social and healthcare system factors to these outcomes.

Property	Value
Organization	Rethink Mental Illness
Population	Adults with severe mental illness
Methods	Observational Study
Outcome	Mortality rates from physical diseases and suicide
Results	Adults with severe mental illness die 15-20 years earlier than peers.

Literature Review: Related Studies

To place these findings in context, we searched the Consensus database (over 200 million papers) using the following queries:

1. severe mental illness life expectancy
2. mental health cancer risk factors
3. chronic disease mortality adults mental illness

Topic	Key Findings
How much does severe mental illness reduce life expectancy?	- Severe mental illness is associated with a 10–20 year reduction in life expectancy compared to the general population 1 2 3 4 5 11 14. - This mortality gap has persisted over decades, with some evidence of slight narrowing in certain countries 5.
What are the leading causes of premature death in people with severe mental illness?	- Physical diseases (cardiovascular, respiratory, liver, cancer) and suicide are the main causes of excess mortality, with natural causes accounting for the majority of deaths 3 4 11 12 13 14. - Suicide and substance abuse contribute disproportionately to external causes of death 3 4 11 12 13.
What factors contribute to excess mortality and can interventions reduce it?	- Modifiable risk factors such as smoking, obesity, physical inactivity, and substance use are major contributors to excess mortality; healthcare disparities and "diagnostic overshadowing" also play a role 12 13 14 15. - Integrated physical and mental healthcare, adherence to guidelines, and preventive interventions can reduce risk, but evidence for long-term mortality reduction is still limited 15.
Is there a link between mental illness and cancer risk or outcomes?	- Depression and anxiety are associated with higher cancer-specific mortality and poorer cancer survival, but not necessarily with higher overall cancer incidence except for lung and smoking-related cancers, where risk factors like smoking may explain the relationship 6 7 10. - Cancer patients with mental illness also experience a high burden of psychological comorbidity 8 9.

How much does severe mental illness reduce life expectancy?

The new Rethink Mental Illness study's finding of a 15–20 year reduction in life expectancy for adults with severe mental illness is in line with a substantial body of international research. Multiple meta-analyses and cohort studies across Europe, North America, and other regions consistently report a 10–20 year gap in life expectancy for people with serious mental illness compared to the general population—a gap that has shown little improvement over time 1 2 3 4 5 11 14.

• Meta-analyses estimate a 14–15 year reduction in life expectancy in schizophrenia and across mental disorders more generally 1 4.
• Large cohort studies from the UK, Nordic countries, and Denmark report similar reductions, with men affected more severely than women 2 3 5 14.
• The mortality gap persists despite improvements in healthcare, and while some narrowing has occurred in certain countries, large disparities remain 5.
• The magnitude of life expectancy loss in severe mental illness is comparable to or greater than that associated with other major risk factors such as smoking and obesity 2.

What are the leading causes of premature death in people with severe mental illness?

Consistent with the Rethink findings, the literature shows that most premature deaths among people with severe mental illness are due to common physical diseases—particularly cardiovascular disease, respiratory diseases, and cancer—followed by external causes such as suicide and substance abuse 3 4 11 12 13 14. Natural causes account for the majority, but suicide and external causes are disproportionately elevated.

• Studies report mortality from cardiovascular and respiratory diseases is two to three times higher in people with severe mental illness 3 4 11 12 13 14.
• Suicide risk is dramatically increased, especially in affective and personality disorders, and contributes significantly to years of life lost 3 4 11 13.
• Substance use, accidents, and ill-defined causes are also major contributors to excess mortality 3 12 13.
• The breakdown of causes in the Rethink study closely parallels patterns seen internationally 3 4 11 12 13 14.

What factors contribute to excess mortality and can interventions reduce it?

Research highlights several modifiable risk factors and systemic barriers that contribute to the premature mortality observed in severe mental illness. These include high rates of smoking, obesity, sedentary lifestyle, substance use, medication side effects, poverty, and fragmented healthcare. "Diagnostic overshadowing," where clinicians misattribute physical symptoms to mental illness, can delay diagnosis and treatment of serious conditions 12 13 14 15.

• Physical health disparities and delayed care are key drivers of excess mortality 12 13 14.
• Evidence suggests that integrated care and guideline-based management of physical health can improve risk factor profiles, but robust evidence for sustained reductions in mortality is still lacking 15.
• Adherence to antipsychotic and antidepressant medications, when properly managed, may offer some protective effect 15.
• Policy and practice interventions targeting both clinical care and social determinants are recommended, echoing the priorities highlighted by Rethink 14 15.

Is there a link between mental illness and cancer risk or outcomes?

The relationship between mental illness and cancer is complex. Several studies indicate that depression and anxiety are associated with poorer cancer outcomes—including higher cancer-specific mortality and reduced survival—but do not generally increase overall cancer incidence, except for lung and other smoking-related cancers where shared risk factors (notably smoking) likely explain the association 6 7 10. Additionally, cancer patients face elevated rates of depression, anxiety, and other psychological disorders, increasing the burden of morbidity 8 9.

• Cancer-specific mortality is elevated in people with severe mental illness, and survival rates are poorer, especially in those with comorbid depression or anxiety 6 7 10.
• The observed higher incidence of lung and smoking-related cancers in people with mental illness is likely mediated by behavioral risk factors such as tobacco use 10.
• Mental health comorbidities are highly prevalent among cancer patients, yet psychological support is often underutilized 8 9.
• These findings support the Rethink study's emphasis on cancer as a leading cause of death and highlight the need for integrated physical and mental healthcare.

Future Research Questions

While the evidence base for excess mortality in severe mental illness is robust, important gaps remain. Future research should address the mechanisms underlying these disparities, evaluate the effectiveness of integrated interventions, and explore ways to reduce diagnostic overshadowing and systemic barriers to care.

Research Question	Relevance
What are the most effective interventions for reducing premature mortality in severe mental illness?	Identifying interventions that produce sustained reductions in mortality is crucial, as current evidence for long-term benefits remains limited despite promising results from integrated and guideline-based care 14 15.
How does diagnostic overshadowing impact physical health outcomes in people with severe mental illness?	Diagnostic overshadowing is recognized as a significant barrier to timely diagnosis and treatment of physical illness, but more research is needed on its prevalence and impact on outcomes 12 13 14.
What is the role of social determinants (such as poverty and housing) in excess mortality among people with severe mental illness?	The contribution of social determinants is acknowledged, but further research could inform policy and intervention design to address these upstream factors 14 15.
How can healthcare systems improve integration of physical and mental health services for this population?	Fragmented care is a key driver of poor outcomes; understanding how to effectively integrate services remains an important area for research and practice innovation 14 15.
Are there specific biological mechanisms linking severe mental illness to increased risk for physical diseases?	Exploring molecular and physiological pathways could offer new targets for prevention and treatment, complementing behavioral and healthcare system approaches 7 14.

Continued research and policy efforts are needed to address the stark mortality gap faced by people with severe mental illness, with an emphasis on both effective medical interventions and broader social and healthcare reforms.