Global Perspectives on Social Relationships and Cognitive Decline in Older Adults: Insights From Cohort Studies in the U.S., Mexico, England, and China

Background This research aimed to explore associations between social relationships and annual cognitive decline in older adults globally. Methods Harmonized data from 4 longitudinal aging cohorts across the U.S., Mexico, England, and China were included. Participants (aged ≥55) with social relationship data and repeated cognitive assessments were analyzed, excluding dementia cases. Linear mixed models assessed associations between social relationship markers and annual rate of cognitive decline, with effects pooled via two-stage random-effects meta-analysis. Results Among 29,805 participants, living with others was associated with slower decline in episodic memory (b = 0.086, 95%CI: 0.013 to 0.158) and global cognition (b = 0.025, 95%CI: 0.013 to 0.038). Felt loneliness was associated with faster decline in episodic memory (b = −0.087, 95%CI: −0.140 to −0.034) and global cognition (b = −0.023, 95%CI: −0.040 to −0.006). Conclusions Good social relationships were associated with slower cognitive decline, while poor social relationships with faster decline.