LONDON — Most Britons underestimate how much severe mental illness (SMI) reduces life expectancy. New research shows the public thinks SMI cuts lives by only seven years, but the real gap reaches 15 to 20 years.
A collaboration between King’s Health Partners, Maudsley Charity, and the Policy Institute at King’s College London uncovered this major misunderstanding. Their study highlights a “hidden health crisis” affecting more than 500,000 people in the UK who live with schizophrenia, psychosis, or bipolar disorder.
Only 11 percent of surveyed adults correctly estimated the mortality gap.
The researchers found that SMI reduces life expectancy more sharply than diabetes, severe obesity, or smoking, which each cut lifespan by up to 10 years.
The survey, which involved 2,000 adults, also revealed confusion about what drives early death among people with SMI. Half of respondents believed suicide causes most of the excess deaths, although suicide accounts for only about 9 percent.
Most respondents did not recognize that cardiovascular and respiratory diseases cause the largest share of premature deaths in people with SMI.
Gaps in awareness around inequalities remain just as wide. Only 14 percent of the public knew that SMI appears more often among Black African and Black Caribbean Britons. Less than half understood its strong association with poverty and urban living.
Despite these misconceptions, most people support action. Two-thirds (67 percent) believe better healthcare could help people with SMI live longer. Opinions split, however, on whether the NHS can deliver that improvement or should prioritize it.
The study also tracks shifts in how the public views major health threats. Around 45 percent now see mental health and cancer as the UK’s biggest health challenges. Although 72 percent believe mental and physical health deserve equal attention, only 33 percent think the healthcare system treats them equally.
Professor Matthew Hotopf, deputy executive director at King’s Health Partners, emphasized the urgency of the issue.
“People with severe mental illness face one of the greatest health inequalities of our time, dying 15 to 20 years early,” he said. “Our findings show that many people do not see the scale of this gap or understand that treatable physical health conditions drive most of these deaths. This crisis needs urgent attention, and King’s Health Partners intends to push for that change.”
Sources:
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King’s Health Partners, Maudsley Charity, and Policy Institute at King’s College London — UK public attitudes survey on severe mental illness (2025).
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Anadolu Agency report: Severe mental illness shortens lives more than smoking, obesity, London, 2025.
