Loneliness, social isolation, and chronic disease outcomes

Abstract Background Research suggests that loneliness and social isolation are serious public health concerns. However, our knowledge of the associations of loneliness and social isolation with specific chronic diseases is limited. The present prospective cohort study investigated (a) the longitudinal associations of loneliness and social isolation with four chronic diseases (cardiovascular disease [CVD], chronic obstructive pulmonary disease [COPD], diabetes mellitus Type 2 [T2D], and cancer), (b) the synergistic association of loneliness and social isolation with chronic disease, and (c) baseline psychological and behavioral explanatory factors. Methods Self-reported data from the 2013 Danish “How are you?” survey (N = 24,607) were combined with individual-level data from the National Danish Patient Registry on diagnoses in a 5 year follow-up period (2013-2018). Results Cox proportional hazard regression analyses showed that loneliness and social isolation were independently associated with CVD (loneliness: adjusted hazard ratio (AHR) = 1.20, 95% confidence interval [CI; 1.03, 1.40]; SI: AHR = 1.23, 95% CI [1.04, 146]) and T2D (loneliness: AHR =1.90, 95% CI [1.42, 2.55]; SI: AHR = 1.59, 95% CI [1.15, 2.21]). No significant associations were found between loneliness or social isolation and COPD and cancer, respectively. Likewise, loneliness and social isolation did not demonstrate a synergistic effect on chronic disease. Multiple mediation analysis indicated that loneliness and social isolation had an indirect effect on CVD and T2D through both baseline psychological and behavioral factors. Conclusions Loneliness and social isolation were independently associated with a diagnosis of CVD and T2D within a 5 year follow-up period. The associations of loneliness and social isolation with CVD and T2D were fully explained by baseline psychological and behavioral factors. Key messages Individuals exposed to loneliness and social isolation constitute vulnerable groups in risk of chronic disease. Psychological and behavioural factors explain the associations with chronic disease.