The researchers said their exercise programme "does not slow cognitive decline in people with mild to moderate dementia". And the number of people who declined to participate in the study was high; more men than women participated, even though dementia is more common in women in western Europe.
For the latest study, scientist took 494 people in England who had been diagnosed with the dementia, and assigned 329 of them to exercise. "A moderate exercise program over a longer period of time may be beneficial; I don't think this research is definitive in that regard". They were recruited through memory clinics - specialist services that help people who have problems with their memory - and GP surgeries.
The DAPA trial was funded by the National Institute for Health Research (NIHR) and received additional support from the NIHR Local Clinical Research Networks and NIHR Oxford CLAHRC and Biomedical Research Centre.
Participants were an average 77 years old, and 61% were men.
Due to the widespread belief that exercise is beneficial for delaying dementia, a team of United Kingdom researchers conducted a study to assess for themselves the effect of physical activity on the symptoms of dementia.
Participants were then assessed at six and 12 months after starting the programme.
The authors added, "These benefits do not, however, translate into improvements in cognitive impairment, activities in daily living, behaviour, or health-related quality of life".
Getty ImagesDementia The exercise group showed a slightly higher mental decline
Exercise undertaken by the aerobic and strength exercise group involved two gym sessions lasting for an hour to one hour and 30 minutes twice a week for four months.
"This new research shows that groups of people with less money have a higher risk of developing dementia, possibly because they are more likely to have poorer medical care".
The primary outcome was the Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog 11-item scale, score of 0 to 70 with higher scores indicating worse cognitive impairment) at 12 months.
There were also no differences between the groups in the other outcomes assessed, such as the number of falls and quality of life. But recent reviews of trials of exercise training in people with dementia have shown conflicting results.
According to Alzheimer's Research UK, the average annual cost per person for someone with dementia, with regards to NHS care, care homes, and unpaid care from friends and relatives, can be huge. This suggests the type of exercise programme may not have been particularly attractive, particularly to women with dementia.
The study found that cognition declined in both groups.
While the study did not find any benefit for dementia patients, this does not mean exercise is not useful for people without dementia.