Exercise linked to lower mortality risk in dementia patients

Physical activity of any intensity after a dementia diagnosis is associated with an approximately 30% lower risk of death, according to research published online in the British Journal of Sports Medicine.

The findings lead the researchers to conclude that those affected should be encouraged to maintain or start an exercise routine, especially since the average life expectancy after a diagnosis of dementia may only be about 4 to 5 years.

Previously published research has linked physical activity to a lower risk of death in people with the disease, but these studies have focused on a single time point. So it’s not clear whether changes in the amount or intensity of physical activity before and after diagnosis could have an impact, the researchers say.

To investigate this further, they used data from the Korean National Health Insurance Service Database, involving 60,252 people who had recently been diagnosed with dementia between 2010 and 2016 and who had undergone a health checkup two years before and after their diagnosis .

The average age of participants was 74, and 43,276 (72%) of them had Alzheimer’s disease and 7,536 (12.5%) had vascular dementia.

At each of the controls, physical activity was assessed using the International Physical Activity Questionnaire – Short Form (IPAQ-SF).

Exercise, such as running, aerobics, fast cycling, and climbing for more than 20 minutes, was defined as vigorous intensity; moderate intensity included brisk walking, doubles tennis, and cycling at a steady pace for more than 30 minutes; light intensity included activities, such as walking for more than 30 minutes.

Regular physical activity was defined as vigorous-intensity exercise, three or more times per week, for at least 20 minutes, or moderate-intensity exercise, five or more times per week, for at least 30 minutes.

Participants were categorized based on changes in regular physical activity in the two years before and after their diagnosis: non-exercisers (78%; 47,050); quitters (just over 10%; 6212); entrees (8%; 4801); and maintainers (just over 3.5%; 2189).

During an average monitoring period of almost 4 years until the end of 2019, 16,431 (27%) of the study participants died.

Long-term participation in regular physical activity before and after a dementia diagnosis was associated with the greatest reduction in the risk of death, regardless of the type of dementia.

And higher physical activity levels after diagnosis were associated with a decrease in the risk of death, which depended on amount, but not intensity.

Compared to staying inactive, maintaining an exercise routine was associated with a 29% lower risk of death. If this was a light intensity, the risk was 30% lower. The reduction in risk for moderate- and vigorous-intensity activity was 26% and 30%, respectively.

And starting exercise of any intensity after diagnosis was associated with at least a 20% lower risk of death.

When physical activity is considered as a continuous variable, the risk of death decreased by 3% for every 100 MET weekly increase – equivalent to adding 5 minutes of brisk walking on five days of the week – in physical activity after diagnosis for all types of dementia.

METs express the amount of energy (calories) expended per minute of physical activity, relative to the energy expended at rest.

This is an observational study and therefore cannot determine cause. And the researchers acknowledge that their findings may be due to reverse causality, where people with less severe dementia and less functional impairment would be more likely to remain physically active. Information about the type of physical activity participants said they did was also not available.

Nevertheless, the researchers say: “Building on the established protective effect of [physical activity] against all-cause mortality, our study suggests that even at low levels [physical activity] could significantly reduce the risk of mortality in people with dementia.”

They conclude: “Our study highlights the potential clinical value of encouraging people with dementia to maintain or initiate physical activity, regardless of intensity, following their dementia diagnosis.”