The Impact of Social Isolation on Subjective Cognitive Decline in Older Adults: A Study Based on Network Analysis and Longitudinal Model

TL;DR

This study investigates how social isolation influences subjective cognitive decline in older adults, revealing depression as a key mediator through network and longitudinal analysis during pandemic restrictions.

Contribution

It introduces a combined network and longitudinal modeling approach to elucidate the mediating role of depression in social isolation-related cognitive decline.

Findings

Depression mediates the effect of social isolation on cognitive decline.

Social isolation predicts subsequent depression, which then predicts cognitive decline.

The mediating pathway is consistent across online and offline social interactions.

Abstract

Social isolation (SI) in older adults has emerged as a critical mental health concern, with established links to cognitive decline. While depression is hypothesized to mediate this relationship, the longitudinal mechanisms remain unclear. This study employed network analysis and cross-lagged modeling to examine these relationships during pandemic-related social restrictions. We collected data from 1,230 older adults (Mage=64.49, SD=3.84) across three timepoints (during lockdown, immediately post-lockdown, and 6 months later). Network analysis identified depressive symptoms (particularly PHQ-9 item 9) as central nodes bridging SI and subjective cognitive decline (SCD). Longitudinal analyses revealed: 1) T1 SI predicted T2 depression; 2) T2 depression predicted T3 SCD. These patterns held for both online and offline SI, with excellent model fit. Our findings demonstrate depression's mediating role in the "SI-depression-SCD" pathway, highlighting how reduced social connections may gradually impair cognitive self-assessment through depressive symptoms. The results underscore the universal mental health impact of SI, regardless of interaction modality (virtual/in-person). These insights suggest that combined interventions targeting both social connection and depression management may be particularly effective for mitigating age-related cognitive decline.