Prolonged social isolation and cognitive function in older adults: lack of informal social contact versus formal social activity as the source of social isolation

Objectives: This study investigates the cognitive function trajectories associated with prolonged social isolation, while distinguishing between a lack of informal social contact and a lack of formal social activity as the source of social isolation. Methods: Data from the Korean Longitudinal Study of Ageing spanning 12 years between 2006 and 2018 were analyzed. A lack of frequent informal social contact or formal social activity was used to assess social isolation, and cognitive function was measured by Korean Mini-Mental State Examination. Fixed effects regression models were used to account for unobserved individual-level confounders. Results: A prolonged absence of frequent informal social contact was linked to a decline in cognitive function up to the three waves of exposure (b = −2.135), but cognitive function has not declined further since then. A persistent lack of formal social activity was associated with a decline in cognitive function up to the fifth and subsequent waves of exposure (b = −3.073). No gender differences were observed in these relationships. Conclusion: Prolonged social isolation, particularly a lack of formal social activity, can pose a significant threat to the cognitive health of older adults.