The 15-to-20-Year Mortality Gap for Severe Mental Illness Explained
Adults with severe mental health problems in England die 15 to 20 years earlier than the wider adult population, according to a Rethink Mental Illness analysis of NHS data The Guardian. Adults with severe mental illness are 4.8 times more likely to die before age 75 than the general population.
What the data show
Secondary mental health services are specialist NHS services for more complex conditions, usually after referral from primary care. Among adults under 75 referred to those services, the risk of death is higher across physical diseases and suicide. Compared with people who were not referred, they are 6.3 times as likely to die from liver disease, 6 times as likely to die from respiratory illness, 3.8 times as likely to die from cardiovascular disease and 2.3 times as likely to die from cancer. They are 14.6 times as likely to die due to suicide.
Cancer, cardiovascular disease, liver disease and respiratory disease accounted for 56.5% of deaths among 18- to 74-year-olds with severe mental health problems in England in 2022-2024. Suicide makes up a smaller share of all deaths but has the highest relative risk.
Why physical illness matters most
Rethink Mental Illness published the 'Closing the Mortality Gap' report on tackling health inequalities for people living with severe mental illness Rethink Mental Illness. The organisation states that early deaths are mostly due to preventable physical illnesses rather than mental illness itself. People living with severe mental illness are more likely to develop long-term conditions such as cardiovascular disease, diabetes and respiratory illnesses.
Smoking, poor diet and low physical activity affect people living with severe mental illness at higher rates. Rethink Mental Illness defines diagnostic overshadowing as "physical health symptoms being wrongly put down to someone's mental illness, meaning real physical health problems can be missed or ignored." Its report recommends integrating mental and physical healthcare for tailored, person-centred support.
Earlier data provide context. In England in 2018 to 2020, 120,273 adults with severe mental illness aged 18 to 74 died, an average of just over 40,000 per year. A 2018 study on premature mortality among people with severe mental illness reported a mean age at death of 72.7 years with a range of 15 to 108 years in the combined cohort.
What would have to change
The broader context here is that mental and physical health care often operate separately, like separate clinics treating the same patient from different files. For clinicians and commissioners working in integrated care systems, which are local partnerships that plan NHS services, a referral to secondary mental health care identifies a group with sharply higher risk from common, treatable conditions, not only from psychiatric crisis. That affects screening, follow-up and who takes responsibility for physical health monitoring.
Looking at what this means for policy, the question is where accountability for closing the gap sits. Prevention is possible. Smoking cessation, cardiometabolic monitoring — regular checks of heart health, blood pressure, weight and blood sugar — cancer screening uptake, liver and respiratory disease management, and safeguards against diagnostic overshadowing fall across primary care, secondary mental health services and public health. The test will be whether integration moves from referral pathways and co-location to shared records, joint responsibility for physical health checks, and measurable reductions in premature mortality among 18- to 74-year-olds.
