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

Abstract

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

Methods: 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.

Results: 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.

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