[Association between Social Relationships and Domain-specific Cognitive Functions among Community-dwelling Older...

In this study, we aimed to clarify the association between social relationships and specific domains of cognitive function in older adults.

The participants were 1,409 community-dwelling individuals aged 65-95 years (mean age: 68.7 years) who had not received treatment for cognitive impairment. Their cognitive function was assessed using the Japanese version of the Mini-Mental State Examination (MMSE-J), which evaluates six domains: orientation, registration, attention, recall, language, and figure copying. Social relationships were measured using the Index of Social Interaction (ISI), which consists of 18 items across five subdomains: independence, social curiosity, interpersonal interaction, social participation, and sense of safety.

Although MMSE-J domain scores were high, attention showed greater variability between individuals and declined earlier than other domains, whereas registration and figure copying remained relatively stable. Multivariate-adjusted logistic regression analyses revealed that reduced social curiosity was associated with lower scores across multiple cognitive domains. A lower score for independence in daily life was associated with lower scores in recall and language, and limited social participation was linked to lower scores in orientation and figure copying. Furthermore, age-related patterns were observed. Among individuals under 75 years, reduced social curiosity was associated with cognitive decline. In contrast, among those aged 75 years and over, cognitive decline was more strongly associated with a lack of safety, fewer interpersonal interactions, and limited social participation.

These findings suggest that the association between social relationships and cognitive function varies across cognitive domains and differs by age group, providing valuable information for developing support and preventive strategies for older adults.