Perceived social isolation and cognitive functioning. Longitudinal findings based on the German Ageing Survey

Objectives There is a lack of longitudinal studies, which are both based on nationally representative samples and use standardized instruments to quantify social isolation. Thus, the purpose of this study was to determine the link between perceived social isolation and cognitive functioning longitudinally. Methods/Design Longitudinal data with n = 6420 from 2014 (wave 5) to 2017 (wave 6) were drawn from the German Ageing Survey (nationally representative sample of individuals aged 40 years and over). Perceived social isolation was assessed using a scale by Bude and Lantermann. Cognitive functioning was quantified using the established digit symbol test. To reduce the problem of unobserved heterogeneity, linear fixed effects regressions were used. Results Regressions showed that increases in perceived social isolation were associated with decreases in cognitive functioning. With regard to covariates, decreases in cognitive functioning were associated with increases in aging and worsening self-rated health, whereas changes in marital status, employment status, income, physical functioning, and physical illnesses were not associated with the outcome measure. Conclusions Based on a nationally representative sample and exploiting the panel data structure, the study findings extend current knowledge by showing that increasing perceived social isolation contributes to decreases in cognitive functioning among individuals aged 40 years and over longitudinally. Future longitudinal studies based on panel data methods are required to validate the study findings.