Abstract
OBJECTIVE: To examine the association between types of loneliness (transient, incident, and chronic) and the risk of functional disability. METHODS: Data were from the Health and Retirement Study 2006/2008-2016/2018. A total of 7,148 adults aged ≥50 was included. Functional status was measured by activities of daily living (ADL) and instrumental activities of daily living (IADL). Loneliness was assessed using the 3-item UCLA Loneliness Scale. We defined loneliness as no/transient/incident/chronic loneliness based on the pattern and duration of loneliness across 2006/2008 and 2010/2012. We applied multivariate Cox proportional hazard models with the new-onset ADL/IADL disability as outcome. RESULTS: Overall, 69.3% respondents showed no loneliness; while 10.3%, 8.9%, and 11.5% showed transient, incident, and chronic loneliness, respectively. A total of 1,298 (18.16%) and 1,260 (17.63%) functionally normal respondents developed ADL and IADL disability during 36,294 person-years of follow-up, respectively. After adjusting for socio-demographic, behavioral, and health factors, chronic loneliness was associated with higher risks of ADL (hazard ratio [HR] = 1.37, 95% confidence interval [CI] = 1.16-1.63, p <0.001, χ(2) = 3.60, degree of freedom [df] = 1) and IADL disability (HR = 1.25, 95% CI = 1.09-1.44, p = 0.002, χ(2) = 3.17, df = 1) compared to no loneliness. By contrast, no significant associations between transient loneliness and ADL (HR = 1.17, 95% CI = 0.88-1.57, p = 0.273, χ(2) = 1.10, df = 1) or IADL disability (HR = 1.16, 95% CI = 0.97-1.39, p = 0.112, χ(2) = 1.59, df = 1) were found. Chronic loneliness was not associated with the risk of IADL disability in men (HR = 1.13, 95% CI = 0.91-1.40, p = 0.263, χ(2) = 1.12, df = 1). CONCLUSION: Chronic loneliness, rather than transient loneliness, is an independent risk factor for functional disability in middle-aged and older adults, especially for women.