Exercise does not appear to help delay the progression of dementia in people with early stages of the disease and may actually speed up mental degeneration, a new clinical trial has found.
Keeping active throughout your life helps reduce the risk of suffering from the neurodegenerative disease, but researchers from Oxford University sought to test recent suggestions that it can help people who have already been diagnosed.
They tested a four-month exercise regime aimed at improving the strength and aerobic fitness of people with mild or moderate dementia, with the ambition that it could be used by the NHS if found to be effective.
While the regime improved the physical health of participants in the short term, this did not translate into improvements in their day-to-day independence – including lowering their risk of falls – or produce quality of life or behavioural benefits.
“There is also the possibility that the intervention could worsen cognition,” the authors add.
There are 47.5 million people worldwide with dementia, a collective term for a host of symptoms affecting memory, thinking and behaviour, but which is most commonly caused by Alzheimer’s disease.
In 2012, former prime minister David Cameron made finding a cure, or remedy to alleviate symptoms, a national research priority in a bid to avert 1.1 billion people in England being affected by 2030 – at a cost of £3bn a year to the economy.
Reviews of existing studies have found some evidence that exercise can play a role, and the idea “that aerobic and strengthening exercise might slow cognitive impairment in dementia has gained widespread popularity”, the authors of the study published today in the BMJ said.
To test this the team from Oxford and the University of Warwick recruited 494 people – with an average age of 77 – from memory clinics across England.
They assigned 329 to the exercise programme and 165 were designated to receive normal care.
After 12 months, test of relative cognitive impairment – measured as an Alzheimer’s Disease Assessment Scale score – found average impairment had increased to 25.2 in the group given exercise, compared to 23.8 in the control group.
“This indicates greater impairment in the exercise group,” the authors note.
While this was statistically significant, it was only a small difference and suggests the type and intensity of exercise should be studied in more depth.
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But the study represents one of the largest controlled trials of the impact on exercise in dementia to date, and independent researchers said these findings should be taken seriously.
Dr Elizabeth Coulthard, consultant senior lecturer in dementia neurology at the University of Bristol, said this adds to some earlier data from a smaller trial suggesting moderate or high intensity activity might worsen dementia.
“Based on these data, we cannot recommend exercise as a tool to help slow cognitive decline in dementia,” she added.
Professor Robert Howard, professor of old age psychiatry at UCL, said the “tiny worsening” in impairment may not be noticeable in an individual patient but is significant within a larger population and would have been welcomed if an improvement of the same size had been seen.
“On this basis, I don’t think we should ignore the possibility that exercise might actually be slightly harmful to people with dementia.”
These results come as a separate study by UCL, published today in JAMA Psychiatry, found that in older people in England those from the poorest backgrounds were twice as likely to develop dementia as the wealthiest people – even if they had the same level of education.