How much does loneliness actually raise your risk of heart disease?
The numbers are striking and consistent across different populations. A massive UK Biobank study of over 442,000 people found that feeling lonely increased the risk of developing coronary heart disease by 15% over nearly 15 years, and being socially isolated raised the risk by the same amount [1]. A study of older Chinese adults found an even larger effect: lonely individuals had a 28% higher risk of cardiovascular disease, and those who lived alone and often felt lonely had more than double the risk [8]. Another Chinese study of people aged 45 and older reported a 43% higher risk of heart disease and a 28% higher risk of stroke among those who felt lonely [7]. These figures come from studies that controlled for other risk factors like age, smoking, physical activity, and depression, meaning loneliness appears to be an independent risk factor, not just a side effect of being unhealthy or depressed.
Is it worse to be socially isolated or to feel lonely?
This is where the research gets nuanced. Social isolation (having few social contacts) and loneliness (feeling disconnected even if you have contacts) are related but distinct, and they affect heart health differently. A study of over 11,000 older Australians found that social isolation and low social support predicted future heart attacks and strokes, but loneliness alone did not [6]. Similarly, a large UK Biobank analysis showed that social isolation was a stronger predictor of cardiovascular death in men, while loneliness was more strongly linked to death in women [4]. However, the combination is the most dangerous: a study of nearly 58,000 older women found that those who were both socially isolated and lonely had a 13% to 27% higher risk of cardiovascular disease than those with neither [2]. The bottom line: having few social connections is a clear risk factor, but feeling lonely even when you have connections also matters—and having both is worse than either alone.
How could loneliness physically damage your heart?
Researchers are uncovering several biological pathways. One study of young adults (ages 18-35) found that higher loneliness was linked to stiffer arteries—a subclinical marker of cardiovascular disease—even after accounting for depression and social anxiety [9]. This suggests loneliness may directly affect the vascular system. Another study of heart disease patients found that loneliness and repetitive negative thinking (rumination) explained nearly half of the psychological distress patients experienced, and that social support reduced cardiac distress by decreasing both loneliness and rumination [3]. Loneliness also affects behavior: a longitudinal study of coronary heart disease patients found that increases in loneliness over time predicted worse medication adherence, meaning lonely patients were less likely to take their heart medications as prescribed [5]. This creates a vicious cycle where loneliness worsens both the physical and behavioral aspects of heart disease.
About These Sources
This answer is built on 9 peer-reviewed studies — published from 2021 to 2026, 7 from 2024 or later, 7 in Q1 journals, collectively cited 369 times — selected as the most relevant from 15 studies that passed quality screening, drawn from 61 papers retrieved from a database of over 500 million.
Sources used in this answer
Social isolation and loneliness increase the risk of coronary heart disease: Insights from a prospective cohort study
In a UK Biobank study of 442,811 people, both social isolation and loneliness independently increased coronary heart disease risk by 15% over 14.77 years, with Mendelian randomization supporting a causal link.
Evaluation of Social Isolation, Loneliness, and Cardiovascular Disease Among Older Women in the US
Among 57,825 older US women, high social isolation raised cardiovascular disease risk by 8% and high loneliness by 5%, with the combination increasing risk by 13-27%.
Loneliness and repetitive negative thinking mediate the link between social health and cardiac distress in heart disease patients
In 400 heart disease patients, social isolation and repetitive negative thinking were strongly linked to cardiac distress, and social support reduced distress by lowering loneliness and rumination.
Sex differences in the impact of social isolation and loneliness on mortality
In 322,558 UK Biobank participants, social isolation predicted higher cardiovascular mortality in both sexes (stronger in men), while loneliness predicted all-cause mortality only in women.
Loneliness, perceived social support, and their changes predict medical adherence over 12 months among patients with coronary heart disease
In 255 coronary heart disease patients, increases in loneliness over 12 months predicted worse medication adherence, while increases in social support predicted better adherence.
Social isolation, social support and loneliness as predictors of cardiovascular disease incidence and mortality
In 11,486 healthy older Australians, social isolation and low social support predicted incident cardiovascular disease and stroke, but loneliness alone did not.
Association of loneliness with incident cardiovascular diseases in middle-aged and older Chinese adults.
In 8,046 Chinese adults aged 45+, loneliness was associated with a 43% higher risk of heart disease and a 28% higher risk of stroke over 7 years.
Loneliness, Living Alone, and Risk of Cardiovascular Disease Among Older Adults in China.
In 3,661 Chinese adults over 65, loneliness increased cardiovascular disease risk by 28%, and those living alone who often felt lonely had double the risk.
Investigating the relationship between early cardiovascular disease markers and loneliness in young adults
In 66 young adults, higher loneliness was linked to stiffer arteries (shorter pulse transit time), a subclinical marker of cardiovascular disease, independent of depression.