Numerous studies have shown that physical activity is associated with a lower risk of developing cognitive impairment and Alzheimer’s disease. One of the largest and most comprehensive studies to date was conducted using the Cooper Center Longitudinal database to objectively measure midlife cardiorespiratory fitness (CRF) in 19,458 people and compare these data with the development of all-cause dementia in advanced age. Over an average follow-up of 25 years, participants in the top 20 percent of CRF demonstrated a 36 percent lower risk of developing dementia than those in the bottom 20 percent. The investigators concluded that higher CRF levels in middle age may protect against dementia.
How fitness benefits the brain
Research suggests that greater CRF levels may be associated with lower dementia risk through a variety of mechanisms:
- Increased CRF levels are associated with a lower risk for diabetes mellitus and hypertension, which are both risk factors for dementia.
- Consistent physical activity and higher CRF levels also have direct effects on the brain that may lower dementia risk. Higher CRF levels appear to combat brain tissue loss or atrophy, which may be associated with preserved or enhanced cognitive function.
- Structured exercise may decrease amyloid load and increase neuroplasticity and other growth factors.
Personal activity intelligence
A research group in Norway evaluated what they called personal activity intelligence by using a device that measured the amount and intensity of physical activity by changes in heart rate throughout the week, as well as the risk of incident dementia and dementia-
related mortality in 30,000 people.
They found that people who got enough exercise to reduce the risk of cardiovascular disease (CVD) and CVD-related death were also 25 to 38 percent less likely to experience or die from dementia. They concluded that regular moderate to vigorous physical activity is a key modifiable risk factor for the prevention of incident dementia.
How much is enough?
The World Health Organization recommends that every person strive for 150 to 300 minutes of moderate-
intensity exercise, such as brisk walking, or 75 to 150 minutes of vigorous activity (such as jogging) every week. Although previous guidelines suggested that physical activity should be performed in 10-minute or longer bouts, over the past decade, studies have revealed that regularly exercising for just one minute at a time can lower triglycerides, body mass index, Framingham risk score, and waist circumference.
Guidelines also suggest that exercise should include both aerobic work (exercise that makes your heart beat faster) and resistance training at least twice a week. Limiting sedentary behaviors, such as watching television, is also beneficial. Adults ages 65 and older should also work on balance training to reduce the risk of falls.
