Life-Space Activities and Incident Dementia Among Older Adults: Insights From a Cohort Study

Objectives: This study examined the association between life-space activities and incident dementia among older adults.

Study design: A prospective study.

Setting and participants: This study included 2740 older adults (mean age 74.4 years; SD ± 6.2 years; range 65-99 years; 58.8% women).

Methods: Life-space activities were assessed using the Active Mobility Index (AMI). Incident dementia was determined using medical insurance data and long-term care insurance data (mean follow-up, 53.7 months).

Results: During the follow-up period, 326 participants (11.9%) had incident dementia. Participants were classified into 3 groups based on AMI score tertiles: tertile 1, ≤52; tertile 2, 53-77; and tertile 3, ≥78. The Cox proportional hazards model was used to examine the association between AMI scores and incident dementia. Individuals with higher scores had lower hazard ratios (HRs) (tertile 1: reference; tertile 2: adjusted HR, 0.76, 95% CI, 0.59-0.97, P = .027; tertile 3: adjusted HR, 0.49, 95% CI, 0.36-0.68, P < .001; P for trend: <.001). Both the physical and social AMI sub-scores were associated with dementia (P for trend: <.001).

Conclusions and implications: Restricted life-space activity, as assessed using the AMI, was associated with the risk of dementia. In addition, both the physical and social sub-scores were associated with dementia.