The recent study conducted by researchers at the Johns Hopkins Bloomberg School of Public Health highlights the significant impact that minimal physical activity can have on reducing the risk of dementia, particularly among older adults who are frail. According to the study, 35 minutes of moderate to vigorous exercise each week, compared to no exercise at all, can lower the risk of dementia by 41% over a four-year follow-up period. This finding is crucial for frail older adults, who are generally considered to be at a higher risk of adverse health outcomes.
The study further reveals a sliding scale of benefit; as physical activity increases, the risk of dementia correspondingly decreases. Specifically, participants engaging in 35 to 69.9 minutes of physical activity per week saw their risk decrease by 60%, those with 70 to 139.9 minutes per week had a 63% reduction and a notable 69% decrease in risk was observed in individuals who exercised for more than 140 minutes per week. These findings were derived from an analysis of nearly 90,000 adults in the UK; all tracked using smart-watch-type activity trackers that monitored their physical activity levels.
The results of this study, published on January 15 in the Journal of the American Medical Directors Association, are part of a broader narrative that underscores the importance of physical activity in the prevention of age-related diseases like dementia. Dementia, particularly Alzheimer’s disease, is one of the most common conditions in older age, affecting an estimated seven million people in the U.S. alone. It has been increasingly recognised that lifestyle changes, including better management of cholesterol, blood pressure, and blood sugar levels, alongside increased physical activity, can potentially mitigate the risk of developing dementia.
Dr Amal Wanigatunga, the study’s lead author and an assistant professor in the Bloomberg School’s Department of Epidemiology, emphasised the significance of their findings. He pointed out that even an incremental increase in physical activity—such as five minutes per day—could reduce dementia risk for older adults. This is particularly pertinent given the challenge many older adults face in meeting the high levels of exercise recommended by health guidelines, which typically advocate for at least 150 minutes of moderate-intensity exercise per week.
The study’s methodology involved extensive data analysis from the UK Biobank project, which tracked 89,667 adults, primarily in their 50s and older, using wrist-worn accelerometers. These devices monitored the participants’ physical activity over a week between February 2013 and December 2015, with health follow-ups continuing until November 2021. During the follow-up period, 735 participants were diagnosed with dementia. The analysis accounted for various factors, including age and pre-existing medical conditions, and it revealed a strong association between increased physical activity and decreased risk of dementia. This association held even when adjusting for individuals with varying degrees of frailty.
Interestingly, the study also considered the potential for reverse causation—whereby early, undiagnosed dementia could lead to decreased physical activity rather than the other way around. By excluding dementia diagnoses from the first two years of follow-up, the researchers confirmed that the association between higher activity levels and lower dementia risk remained robust.
Wanigatunga’s team suggests that these findings should encourage further research, particularly clinical trials, to explore low-dose exercise as a viable strategy for dementia prevention. This approach could significantly alter public health strategies, offering a more accessible and realistic method for increasing physical activity among the older population, which could have a profound impact on the prevalence of dementia and related disorders.
More information: Amal Wanigatunga et al, Moderate-to-Vigorous Physical Activity at any Dose Reduces All-Cause Dementia Risk Regardless of Frailty Status, Journal of the American Medical Directors Association. DOI: 10.1016/j.jamda.2024.105456
Journal information: Journal of the American Medical Directors Association Provided by Johns Hopkins Bloomberg School of Public Health
