The associations of social isolation and loneliness with premature mortality are well known, but the risk factors linking them remain unclear. We sought to identify risk factors that might explain the increased mortality in socially isolated and lonely individuals.
We used prospective follow-up data from the UK Biobank cohort study to assess self-reported isolation (a three-item scale) and loneliness (two questions). The main outcomes were all-cause and cause-specific mortality. We calculated the percentage of excess risk mediated by risk factors to assess the extent to which the associations of social isolation and loneliness with mortality were attributable to differences between isolated and lonely individuals and others in biological (body-mass index, systolic and diastolic blood pressure, and handgrip strength), behavioural (smoking, alcohol consumption, and physical activity), socioeconomic (education, neighbourhood deprivation, and household income), and psychological (depressive symptoms and cognitive capacity) risk factors.
466,901 men and women (mean age at baseline 56.5 years) were included in the analyses, with a mean follow-up of 6.5 years. The hazard ratio for all-cause mortality for social isolation compared with no social isolation was 1.73 after adjustment for age, sex, ethnic origin, and chronic disease, and was 1.26 after further adjustment for socioeconomic factors, health-related behaviours, depressive symptoms, biological factors, cognitive performance, and self-rated health. The minimally adjusted hazard ratio for mortality risk related to loneliness was 1.38, which reduced to 0.99 after full adjustment for baseline risks.
Isolated and lonely people are at increased risk of death. Health policies addressing risk factors such as adverse socioeconomic conditions, unhealthy lifestyle, and lower mental wellbeing might reduce excess mortality among the isolated and the lonely.
Social isolation and health - what are the mechanisms?
According to the loneliness model of Cacioppo, lonely individuals would (1) engage in poorer health behaviours than others, (2) show altered cardiovascular activation, (3) show chronically elevated levels of hypothalamic pituitary adrenocortical activation, and thus lower glucose tolerance, diminished cortisol regulation, poor sleep and decreased cognitive performance, and (4) report more frequent mental health problems. All these four factors are risk factors for increased cardiovascular diseases, diabetes and mortality. This research project aims to investigate the association between social isolation and health and test whether pathways including health behaviours, physiological factors, mental health and socioeconomic position would explain the associations. Study aims to provide knowledge how social isolation affects health, which will help to create better prevention programs to heal individuals who are socially isolated.
We will define social isolation based on the following UK Biobank questions:
709 Number in household
6141 How are people in household related to participant
1031 Frequency of friend/family visits
6160 Leisure/social activities
2110 Able to confide
An individual will be defined as socially isolated if he/she lives alone, doesn't participate in any social activities and can rarely confide to other people. The primary analyses will be performed on all-cause mortality and incidence of major diseases (e.g. coronary heart disease, stroke, cancer and diabetes). In secondary analyses, we will examine whether loneliness is linked with health outcomes (cardiovascular heart disease, diabetes and mortality) through pathways suggested by the loneliness model, including behavioural risks (drinking, smoking, physical activity and diet), physiological risks (blood pressure, obesity, handgrip cholesterol, sleep), mental health (depression and anxiety) and socioeconomic position (education, employment status, income).
Tested using hierarchical regression models, structural equation modeling and bootstrap-models. Full cohort will be used.
|Lead investigator:||Marko Elovainio|
|Lead institution:||National Institute for Health and Welfare|