Exercising regularly does not slow down cognitive decline in people with mild to moderate dementia — and may even make the symptoms worse, according to British researchers.
The study did find that exercise helped people with mild to moderate dementia improve their physical fitness, but those benefits “do not translate into improvements in cognitive impairment, activities in daily living, behaviour, or health related quality of life,” the authors of the study write.
Exercise “cannot be recommended as a treatment option for cognitive impairment in dementia,” they conclude.
How the study was done
Almost 47.5 million people worldwide have dementia, including 4 to 5 million Americans. Alzheimer’s disease is the most common form of dementia, accounting for 60 to 80 percent of all cases in the United States, according to the Alzheimer’s Association.
The idea that both moderate- to high-intensity aerobic (such as brisk walking or cycling) and strengthening exercises might delay cognitive decline has gained considerable credence in recent years. But most of the research in support of that hypothesis has been on animals. Few studies have involved humans.
For the current study, researchers conducted a randomized controlled clinical trial involving 494 people with mild to moderate dementia (average age: 77) living “in the community” (not in nursing homes or other institutional facilities) throughout England.
After their general health and fitness was assessed, the participants were randomly assigned to either a supervised exercise program or to “usual care.”
Those in the exercise program (329 people) took part in 60- to 90-minute group sessions twice a week for four months. Each session involved aerobic exercise (30 minutes of moderate- to hard-intensity cycling on a stationary bike) and strength training (various exercises using hand-held weights). The participants were also encouraged to do home exercises for an additional hour per week. Compliance with the exercise program was good.
Those in the “usual care” group (165 people) received care in accordance with British clinical guidelines, which included counseling, medications for any physical symptoms and brief advice about physical activity.
The participants in both groups had their cognitive abilities and physical fitness assessed at the start of the study and then six and 12 months later.
The study found that cognition declined in both groups. In fact, the decline was steeper in the exercise group, although, as the researchers point out in their paper, the average difference between the two groups was small and the “clinical relevance was uncertain.”
The study also found that so-called secondary outcomes (ones that weren’t the primary focus of the study) — such as the participants’ ability to perform activities of daily living, their neuropsychiatric symptoms, the number of falls they had, their health-related quality of life and the quality of life of the family members caring for them — were also similar in both groups.
The people in the exercise group tended to be more physically fit at the end of the study, however.
Limitations and implications
The study has several important limitations. It involved a relatively small number of people (although much larger number than earlier clinical trials on the topic), and lasted for only 12 months — a period of time too short, perhaps, to produce positive results among the exercise group. Also, both the participants and their family caregivers knew which group they were in, a factor that could have affected the results.
Still, this study is the most robust one to date to investigate the effect of exercise on dementia.
“I was disappointed by the results, although I probably wasn’t completely surprised,” Sarah Lamb, the study’s lead author and a researcher at Oxford University, told Guardian reporter Sarah Bosely.
“I think it would be fair to say that dementia is a difficult problem to fix,” she added.
Lamb doesn’t want people with dementia to stop being physically active, however.
“We don’t want to alarm members of the public with dementia and their families,” she said.” We used a very specialized exercise program. We know that gentle exercise is good for you. We don’t want people to stop what they are doing.”
FMI: You can read the study in full on the BMJ’s website.