Although it improved short-term physical fitness, this "did not translate to improvements in activities of daily living, behavioural outcomes or health-related quality of life".
Among patients with dementia, exercise is beneficial for improving physical fitness, but it can not be recommended as a treatment option for slowing cognitive impairment in dementia.
According to a new study, high-intensity exercise does not ease the symptoms of dementia.
Indeed, patients who participated in the exercise programme showed slightly worse scores. "We don't want people to stop what they are doing".
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 average age of the group was 77.
ADAS-cog results run on a scale from 0 to 70, with higher scores suggesting greater impairment.
The study found the exercise group did not experience any difference in the ability to perform daily living tasks or the number of falls, when compared with their non-exercising peers.
Over the 12-month follow-up period, cognitive impairment declined in both groups. "We did not pre-specify a value for a negative effect, but the average effect observed was smaller than our pre-specified superiority target of 2.45 ADAS-cog points".
Whether dementia in these patients was too advanced to be affected by the intervention is unknown.
"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.
"It also may be that vigorous exercise is not the solution".
While physical exercise may keep off dementia, however it does not delay the mental decline in old people after they have been diagnosed, a study conducted 500 people with the condition reported on Thursday (May 17).
The study has several important limitations.
The disappointing results are a setback for researchers, who had hoped an exercise programme might improve people's ability to carry out everyday tasks such as washing and dressing. 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 carried out a randomised controlled trial (RCT), which is usually the best way to see if a treatment works.
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.
The researchers reported having no conflicts of interest.