Chronic loneliness and the risk of incident stroke in middle and late adulthood: a longitudinal cohort study of U.S. older adults.

Background: Loneliness has been implicated as a stroke risk factor, yet studies have examined loneliness at only one time point. The association of loneliness changes and risk of incident stroke remains understudied. Our aim was to examine the association of loneliness with incident stroke, particularly the role of loneliness chronicity. Methods: This prospective cohort study examined data from the Health and Retirement Study during 2006-2018. For analyses examining baseline loneliness only, we included U.S. adults aged 50 years or older and stroke-free at baseline and excluded individuals missing data on loneliness and those who experienced death at baseline. For analyses examining loneliness changes over two time points, we included those aged 50 years or older at baseline and stroke-free through the exposure measurement period. Individuals missing a loneliness scale measure or those who experienced death during the exposure measurement period were excluded. Loneliness was measured with the 3-item Revised UCLA Loneliness Scale. We constructed loneliness scores (range 3-9), dichotomized loneliness measures (high vs low using a >6 cutoff), and loneliness patterns across two time points (consistently low, remitting, recent onset, consistently high). Cox regression models estimated associations of baseline loneliness (N = 12,161) with incident stroke over a 10-12-year period, and loneliness change patterns (N = 8936) with incident stroke over a subsequent 6-8-year period, adjusting for demographics, health behaviors and health conditions. Findings: Higher loneliness scores at baseline were associated with incident stroke for continuous (hazard ratio [HR]: 1.05, 95% confidence interval [CI]: 1.01-1.08) and dichotomized (HR: 1.25, 95% CI: 1.06-1.47) loneliness measures, and persisted after adjustment for social isolation but not depressive symptoms. Only individuals with a consistently high loneliness pattern over time (vs consistently low) had significantly higher incident stroke risk (HR: 1.56, 95% CI: 1.11-2.18) after adjusting for depressive symptoms and social isolation. Interpretation: Chronic loneliness was associated with higher stroke risk independent of depressive symptoms or social isolation. Addressing loneliness may have an important role in stroke prevention, and repeated assessments of loneliness over time may help identify those particularly at risk. Funding: National Institute on Aging (NIA U01AG009740).