Regular Exercise Correlates with Decreased Dementia Risk
Studies of correlations between physical activity and long term health tend to show a large difference in outcomes between people who are sedentary versus people who exercise even a little; it is a big step up to go from no exercise to a little exercise. The dose response curve for physical activity as an intervention starts out quite steep, and then further activity even beyond the present recommendations of 150 minutes per week continues to add benefits in terms of reduced mortality and reduced risk of age-related disease.
Dementia, usually from Alzheimer's disease, is one of the most common conditions of old age. It is estimated to affect about seven million people in the U.S., including about a third of those who are 85 years or older. Although the risk of dementia rises with age, studies in recent years have suggested that dementia is somewhat preventable, within a normal lifespan, by lifestyle changes that include better control of cholesterol, blood pressure, and blood sugar, and being more active.
Researchers analyzed data on British adults generated as part of the UK Biobank project, a long-running, ongoing study of approximately 500,000 individuals. The dataset for the new study covered 89,667 adults, mostly in their 50s and older, who used wrist-worn accelerometers to track their physical activity for a week during the period from February 2013 to December 2015. Follow-up of their health status extended for an average of 4.4 years, through November 2021, during which 735 of the participants were diagnosed with dementia.
The analysis compared individuals whose trackers showed some weekly moderate to vigorous physical activity to those whose trackers showed none and accounted for age and other medical conditions. The associations between higher activity and lower dementia risk were striking. Participants in the lowest activity category, ranging from one to 34.9 minutes per week, had an apparent risk reduction of about 41% versus sedentary individuals. When the researchers took into account participants who met their definitions of frailty or pre-frailty, they found that the association between more activity and less dementia was essentially unchanged. Dementia risk decreased further with higher amounts of physical activity. Dementia risks were 60% lower in participants in the 35 to 69.9 minutes of physical activity/week category; 63% lower in the 70 to 139.9 minutes/week category; and 69% lower in the 140 and over minutes/week category.