Almost 47.5 million people across the world are estimated to have dementia and the view that exercise might counteract the decline in mental capacity has gained widespread popularity.
Washington D.C. [U.S.A.], May 17: Moderate to high-intensity exercise does not slow cognitive decline in people with dementia, a new research has claimed.
Although the difference between the two groups was small, the researchers say exercise should not be recommended for people with dementia and called for future trials to 'consider the possibility that some types of exercise intervention might worsen cognitive impairment'.
Oxford University studied almost 500 people, with an average age of 77 years, in 15 regions across England who were randomly given either supervised exercise and support programmes, or normal elderly care.
The exercise programme consisted of group sessions of 60 to 90 minutes in a gym twice a week for four months, plus home exercises for one additional hour each week with ongoing support.
The participating individuals who had taken part in an exercise programme were even found to have had slightly worse scores in an Alzheimer's assessment when they were tested a year later.
The authors said the study had shown people with mild to moderate dementia could engage in moderate to high-intensity exercise to improve their physical fitness.
After taking account of potentially influential factors, the researchers found that cognitive impairment declined over the 12-month follow-up in both groups.
Although the exercise programme improved physical fitness, it can not be recommended as a treatment option for cognitive impairment in dementia, say the researchers. For example, participants and carers knew which group they were in, and the period of structured exercise may have been too short to produce positive benefits.
"Whilst previous smaller studies have suggested that exercise can prevent or improve cognitive decline in people with Alzheimer's disease, this robust and very large study provides the most definitive answer we have on the role of exercise in mild-moderate Alzheimer's disease", he said via the Science Media Centre.
However, researchers reported something contrary in The BMJ medical journal.