Exercise in the treatment of dementia
My last two blogs have described some of the problems of dementia and how regular exercise can protect against the development of dementia later in life. How effective, however, may exercise be in treating dementia once it has set in?
As we age our thought processes, like all other bodily functions, slow down. We forget words, names, why we just came upstairs…..frustrating but not insuperable. Exercise does seem to help. “The higher the older adults’ aerobic fitness level, the lower the probability of experiencing a tip-of-the-tongue state.” Also memory is improved after single bouts of exercise.
Mild cognitive impairment (MCI) is extremely common – perhaps universal but only a minority of sufferers progress to dementia. Regular exercise has been shown to reduce the risk of this progression from MCI to full blown dementia. It has been suggested that physical activity may increase the production of molecules that support the growth and survival of neurons or increase blood flow to the brain. This, in turn, could prevent the reduction in brain volume often associated with dementia.
There is evidence that exercise can slow the progression of dementia but it is less certain that it can reverse the process. A recent study on cognition over a period of five years, showed that those who achieved a good level of cardio-respiratory fitness over the age of 70 were able to maintain cognition. It appeared that the mode of exercise was less important. Confirmationc comes from a study which found that “better physical fitness is important for cognition and autonomous functional capacity and that it has positive repercussions on the Quality of Life in institutionalized older adults with dementia.”
The 2015 Cochrane Review of trials of exercise as an intervention for dementia examined 17 trials involving more than 1,000 patients. The main positive finding was that those treated with exercise were more capable of performing activities of daily living, but there was no evidence of improved cognitive function. The results, however, were very variable and the authors found the quality of the trials to be very low.
The hippocampus shrinks in late adulthood, leading to impaired memory and an increased risk for dementia. Hippocampal volumes are larger in higher-fitness adults. A randomised controlled trial with 120 older adults found that aerobic exercise training increased the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by two per cent, effectively reversing age-related loss in volume by one to two years. So it is possible that exercise might reverse some of the effects of dementia.
Exercise appears to increase blood flow into two key regions of the brain associated with memory, including the anterior cingulate cortex and the hippocampus. Low and high intensity exercise have different effects on such functions as cognition, attention processing, and emotion reactions. Also some biomarkers (chemical markers of structure or function) of memory and learning ability are increased after physical training.
The longer term
The management of dementia is a bleak and unrewarding field and individuals must do everything in their power to prevent this disease. The most promising approach is regular exercise. Once dementia has become established,, it seems that it may be too late for exercise to have much effect on cognitive ability. However, there are still important quality of life attributes to be gained for affected individuals.
People with dementia can benefit from improvements in strength, balance, mobility, endurance and quality of life. A particularly valuable advantage is improvement in activities of daily living which help the individuals to maintain their independence.
The World Health Organisation “recommends physical exercise – both aerobic and strength training – for older individuals as a means of reducing cognitive decline.”