Does exercise improve brain function in dementia?
Maybe. There are theoretical reasons to believe that the failing brain might be benefitted by regular exercise. The hippocampus is an area at the base of the brain which is concerned with memory and the processing of information. This region shrinks in late adulthood, leading to impaired memory and increased risk for dementia. Hippocampal volumes are larger in higher-fitness adults. A randomized controlled trial with 120 older adults found that aerobic exercise training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 years, leading to the possibility that exercise might reverse some of the effects of dementia.
Is there any evidence in practice?
A bit. The 2015 Cochrane review of trials of exercise as an intervention for dementia looked at 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. A 2018 review of the findings in 1100 adults average age 73 who had taken part in randomised controlled trials of exercise found that long-term exercise (at least 52 hours over 6 months) improved the brain’s processing speeds in both healthy individuals and those with cognitive impairment. Memory was not improved.
Exercise as part of “Multi-component Interventions”
Multi-component interventions might be more effective than exercise alone. Multicomponent training (MT) combines aerobic, strength and postural training and balance exercises, and has been presented as a promising intervention strategy for dementia. MT brings a potential influence in treating symptoms and/or delaying the disease progression in addition to its intrinsic health benefits. A meta-analysis of a number off trials of MT for dementia patients showed that it benefitted agility/balance, gait speed and strength. The evidence for improving cognition was less good but the authors concluded that “MT may be an important non-pharmacological strategy to enhance physical conditioning on dementia patients, but further evidence is needed for acknowledging its benefits in specific cognitive abilities…”
How could exercise work in either prevention or treatment?
We view the subject of brain function through a glass and very darkly but we do have a glimmering of an understanding of the possible mechanisms by which exercise mediates preservation of normal cognitive function. The region of the brain responsible for memory and spatial awareness is the hippocampus which sits at the base of the brain. This area is one of the first to show loss of tissue in Alzheimer’s disease. Regular exercise in older subjects is associated with slowing of the loss of substance of the hippocampus. One year of aerobic exercise in a large randomised trial of older people was associated with significantly larger hippocampal volumes and better spatial memory. Other trials in seniors have found that exercise slows the age-related grey matter volume loss. Cross-sectional studies similarly reported significantly larger hippocampal or grey matter volumes among physically fit seniors compared with unfit seniors.
Brain cognitive networks studied with functional magnetic resonance imaging display improved connectivity after 6 to 12 months of exercise. The ability of the brain to increase activity and functional nerve connections is known as neuroplasticity and this can be increased by bouts of exercise; the harder the exercise, the greater the effect. These studies support the belief that regular exercise can prevent dementia but also suggest that physical activity could be effective for treating this otherwise pretty well untreatable condition.
The management of dementia is a bleak and unrewarding field and we must do all in our power to prevent it. The most promising approach is regular exercise. Once dementia has progressed too far it is unlikely to have much effect.
I wonder how popular are the various fitness trackers that are now available? And how useful? There is good evidence that pedometers do have some effect on the amount of exercise taken. There are more sophisticated motion detectors know as accelerometers but I have no evidence on these. I suspect that the main users of these wearable technologies are already regular exercisers and use the devices to track their activities rather than encourage them to increase. What do you think?
I would be very interested to hear from those of my readers who use fitness trackers. How helpful are they in maintaining your exercise habit? Which information provided by the tracker is most helpful? – just respond to the blog.