Activity profiles and their associations with transitions between fall and dementia: findings from a multistate...

The potential link between data-driven classifications of individuals' activity profiles and the occurrence of fall and dementia, including within-person transitions from dementia- or fall-only states to their co-occurrence over time, remains unclear.

To examine whether distinct activity profiles were associated with the risk of fall, dementia, and their transitions over time in middle-aged and older adults, this prospective longitudinal study included 288,287 adults (53.6% women) aged 40-69 years at baseline (2006-2010) from the UK Biobank. Latent class analysis was used to classify participants into distinct activity profiles based on self-reported physical activity, transportation, work, social, and sleep behaviours. Incident fall and dementia were identified through linkage to health records and the death registry up to December 2022. Multistate time-to-event analysis was conducted to examine the associations between activity profiles and the risks of fall, dementia, and their transitions over time.

Based on various activity levels and work status, participants were categorized into four groups: active-non-working (29.2%), inactive-non-working (14.4%), active-working (26.7%), and inactive-working (29.7%). Of them, 19,753 (6.85%) experienced a fall injury, and 4,407 (1.53%) developed dementia over an average follow-up of 13.4 years. The inactive-non-working group showed the highest risk of both fall and dementia (HR_range: 1.45-2.38) over 13.4 years. In the non-working groups, where fall and dementia occurred most often, the inactive profile was linked to a higher risk of both fall and dementia, and to an increased likelihood of transitioning between the two. Transitions from dementia to subsequent fall were associated with insufficient physical activity, whereas transitions from fall to subsequent dementia were linked to social isolation, particularly living alone and frequent loneliness. In the working groups, no differences in fall or dementia risk were observed between active and inactive profiles.

This study highlights the important role of social and physical activity in simultaneously preventing fall, dementia, and their transitions, particularly among non-working individuals, including those on sick leave or retired.