The researchers said their exercise programme "does not slow cognitive decline in people with mild to moderate dementia". The participants were also encouraged to do home exercises for an additional hour per week.
"We found a consistent pattern of lack of response across Alzheimer's disease and vascular dementia", Lamb told MedPage Today. It comes after a number of small studies looking at exercise for people with dementia had conflicting results.
People with dementia are now forced to rely on services so starved of funding that they're unable to protect them from harm and the doors of A&E, let alone provide specialist care and support. "We also used completely independent healthcare professionals to measure the outcome using a sensitive and well-recognized test of cognition".
The trial involved 494 people with mild to moderate dementia (average age 77 years) living in the community across 15 regions of England.
For dementia patients who are in the more serious, later stages of the disease the cost per year is around £55,000.
People in the programme took part in 60-90 minute gym sessions over a four month period. Men were more likely to comply than women; otherwise, there were no differences. The exercise group were fitter, but had marginally higher Alzheimer's disease assessment scores compared with the rest. Other (secondary) outcomes included activities of daily living, number of falls, and quality of life.
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"This indicates greater cognitive impairment in the exercise group, although the average difference is small and clinical relevance uncertain", the authors wrote.
"Is 4 months enough?" asked Ronald Petersen, MD, of the Mayo Clinic in Rochester, Minn., and lead author of the American Academy of Neurology (AAN) practice guideline for mild cognitive impairment (MCI), which recently recommended exercise for patients with MCI. We know that gentle exercise is good for you.
Dr James Pickett, Head of Research and Development at Alzheimer's Society, added:"The results are somewhat surprising as we would anticipate that exercise would have positive effects".
It is well known that exercise is beneficial for physical and mental wellbeing, improving strength and cardiovascular fitness as well as boosting mood and self-esteem.
Currently, as a dementia therapy that does not involve medication, the NHS recommends group cognitive stimulation therapy classes, where sufferers undertake exercises created to improve their memory, problem-solving skills and language ability. While some of the headlines were a bit alarmist - such as The Independent's "Exercise could make dementia progression worse not better" - most of the reports were balanced and accurate.
The researchers pointed to some trial limitations.
The researchers reported having no conflicts of interest.