# The 24-Hour Movement Behavior Composition and the Risk of Dementia

## TL;DR

This study finds that how people spend their 24-hour day, including sleep and physical activity, affects their risk of developing dementia.

## Contribution

The study introduces a new approach to assess dementia risk by analyzing the composition of 24-hour movement behaviors.

## Key findings

- More moderate-to-vigorous and light physical activity is linked to lower dementia risk.
- Spending more time sedentary increases dementia risk.
- Reallocation of time from sedentary behavior to other activities reduces dementia risk by 2% to 5% per 15 minutes.

## Abstract

This study examined the relationship between the 24-hour movement behavior composition—including sleep, sedentary time, light physical activity, and moderate-to-vigorous physical activity—and dementia risk.

93,781 participants (mean age: 62 years) from the UK Biobank were studied. The average daily time spent in each movement behavior was determined using accelerometers. Incident cases of dementia were identified over an average 9.6-year follow-up. Cox proportional hazards models with compositional covariates assessed the associations of interest.

Relative time in moderate-to-vigorous and light physical activity were negatively associated with dementia risk while relative time in sedentary behavior was positively associated with dementia risk. Each 15 min/day reallocation of time from sedentary behavior into sleep, sedentary behavior, or physical activity reduced dementia risk by 2% to 5%.

The time-use composition of movement behaviors across the 24-hour day influences dementia risk.