Study Finds Any Amount of Moderate-to-Vigorous Physical Activity Reduces Dementia Risk
A link between physical activity and reduced Alzheimer’s and dementia biomarkers is well established, as shown in recent studies. Physical activity guidelines suggest 150 minutes of moderate-to-vigorous physical activity (MVPA) per week for all adults. However, because this level of activity may be difficult for older and frail individuals, understanding how much activity is necessary to stave off dementia is essential. The authors of a new study in the Journal of the Medical Directors Association set out to determine the minimum amount of exercise required to produce such an effect.
Data were collected from participants in the UK Biobank, a large prospective cohort study that gathers deidentified health data across a variety of parameters to aid in evidence generation. Weekly activity minutes were calculated using data collected via wrist-worn accelerometers, and activity was tracked alongside a person’s frailty, tracked by a standard, objective measure known as the physical frailty phenotype. The primary outcome was time to the first incident of all-cause dementia, assessed with a statistical regression model. A key secondary outcome examined whether frailty status affected the relationship between physical activity and risk of dementia. Frailty status was based on low hand-grip strength, slow walking speed, unintentional weight loss, and self-reported levels of exhaustion and low physical activity.
The final study sample included 89,677 participants with a median age of 63 years. The average MVPA was 89.8 minutes/week. There were 735 first-time events of dementia over an average follow up time of 4.4 years.
A dose-dependent pattern was found, with increasing levels of MVPA associated with greater dementia risk reduction. Specifically, each 30-minute increase in physical activity resulted in a 4% risk reduction. Notably, the lowest amount of MVPA was associated with a 41% risk reduction, suggesting that even a minimal amount of daily exercise may significantly reduce the risk of dementia.
| MVPA, minutes | Hazard ratio (95% CI) | vs 0 minutes MVPA |
| 1-35 | 0.59 (0.40-0.89) | P=0.01 |
| 36-70 | 0.40 (0.26-0.62) | P<0.01 |
| 70-140 | 0.37 (0.24-0.56) | P<0.01 |
| >140 | 0.31(0.20-0.48) | P<0.01 |
The patterns found in this study are not altered by frailty status, showing that exercise levels in all patients can help patients reduce dementia risk. Unsurprisingly though, participants living with pre-frailty or frailty had a significantly higher risk of developing dementia.
“Our findings suggest that promoting any engagement in MVPA for decreasing dementia risk is particularly effective when engagement is low or none—levels common among frail older adults,” state the study authors.
