Cumulative loneliness and memory function among U.S. older adults: the role of depressive symptoms

This study aimed to investigate whether depressive symptoms mediate the association between cumulative loneliness and memory function during aging.

Data were from 4779 adults aged over 50 in the U.S. Health and Retirement Study in two random sub-cohorts from 2006 to 2018 (Cohort A) and 2008 to 2020 (Cohort B). Participants were categorized as experiencing loneliness at 0, 1, 2, or 3 time points over an 8-year exposure period according to the UCLA Loneliness Scale. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale. Episodic memory function was assessed at the follow-up by immediate and delayed word recall scores. Causal mediation analysis was performed in the pooled cohorts.

Mean baseline age (SD) was 65 (7.6), and 62% of the sample was female (2941/4779). Greater cumulative loneliness over the 8-year exposure period was associated with lower subsequent memory function in a dose-response relationship. Observed estimates for loneliness at each of 1, 2, and 3 time points were comparable in magnitude to an additional 0.26, 0.84, and 2.56 years of aging-related memory decline, respectively. The proportion of the association mediated by depressive symptoms decreased from 70% to 21% as the duration of loneliness increased.

Depressive symptoms may be a psychological mechanism through which cumulative loneliness negatively affects memory function among middle-aged and older adults in the USA.