Feeling lonely or socially isolated could significantly increase the chances of developing multiple serious illnesses at the same time, according to new research involving nearly half a million people in the UK. The findings, published in the Archives of Gerontology and Geriatrics, add to growing concern that social well-being is just as important to long-term physical health as diet or exercise.
The study, which analysed data from the UK Biobank cohort, followed over 407,000 adults aged between 37 and 73 years from 2006 to 2010, tracking them for a median of 13.2 years. Researchers from Universidad Autónoma de Madrid examined how a range of social and lifestyle factors influenced the likelihood of developing multimorbidity, defined as having two or more chronic conditions simultaneously.
Loneliness emerged as one of the strongest risk factors, increasing the risk of multimorbidity by 30% compared with those who did not report feeling lonely. Social isolation, measured separately, raised the risk by 15%. The researchers were careful to distinguish between the two: loneliness reflects a subjective sense of disconnection, while social isolation refers to objectively limited contact with others.
Smoking carried the most significant association overall. Current smokers were found to be twice as likely to develop multiple chronic illnesses compared with those who had never smoked. Women who smoked showed an even greater risk than their male counterparts, a finding consistent with earlier research into sex differences in smoking-related health outcomes.
Poor sleep habits and a sedentary lifestyle were also independently linked to a higher risk of multimorbidity. Adults sleeping fewer than seven or more than eight hours per night showed a 23% greater risk than those with optimal sleep duration. Those who spent the most time watching television, used in the study as a proxy for sedentary behaviour, were 22% more likely to develop multiple conditions.
Diet also played a role, though in both directions. Eating more fruit and vegetables was associated with a modest reduction in risk, while consuming processed meat more than once a week increased the likelihood of multimorbidity by 9%. Red meat and oily fish intake showed no statistically significant association.
The nine chronic conditions tracked in the study included diabetes, stroke, coronary heart disease, depression, arthritis, Parkinson’s disease, dementia, chronic obstructive pulmonary disease, and cancer. These were chosen because they represent leading causes of death and disability among middle-aged and older adults in high-income countries.
The researchers noted that previous studies in this area had tended to focus on older populations, whereas this analysis gave particular attention to middle-aged adults, the group in which multimorbidity most commonly begins. Multimorbidity in mid-life places considerable pressure on health systems and is more prevalent among people from socioeconomically disadvantaged backgrounds.
The authors concluded that addressing social connectedness alongside conventional health behaviours should be treated as a public health priority, particularly in community-level interventions targeting chronic disease prevention.