Physical exercise is an important part of a healthy lifestyle, contributing to general fitness, muscle control and coordination, and to a sense of wellbeing. Physical exercise is also essential for maintaining adequate blood flow to the brain and may stimulate brain cell growth and survival.
Evidence of the effects of physical exercise in the prevention of dementia have been supported by many observational studies. The results of randomized trials suggest that exercise leads to increases in brain tissue, including the hippocampus and elevate blood levels of brain derived neurotrophic factor (BDNF), stimulating the formation of new nerve cells (1).
More specifically, aerobic exercise has been shown to positively modify the pathological hallmarks of Alzheimer’s disease (Amyloid β and hyperphosphorylated tau depositions), as well as to reduce neuroinflammation, oxidative stress (free radical formation) and glucose uptake impairment in animal models (2). It can also improve behavior and memory in individuals with mild symptoms of dementia (3).
If, on the one hand, the beneficial effects of aerobic exercise in the prevention and treatment of early stages of AD leave little doubt, its effects in more advanced stages of the disease have shown contradictory results in different clinical trials. The question “Can aerobic exercises delay disease progress in patients with moderate to severe symptoms?”, is still to be answered.
In order to address previous inconsistent findings, a randomized controlled trial was conducted and the results are now published in the Journal of Alzheimer’s Disease (4). In this study, 96 community-dwelling older adults (66 years old or older) with moderate symptoms of dementia were divided in two groups: the intervention group was prescribed 20-50 min cycling, three times per week for 6 months; the control group realized stretching and range-of-motion exercises at the same frequency and duration. Cognition in both groups was assessed before the beginning of the trial and at 3, 6, 9 and 12 months by ADAS-cog – a cognitive scale widely used in clinical trials, including anti-dementia drug trials.
After 6 months, cycling participants had a smaller increase in ADAS-Cog than the natural expected, meaning that the progression of disease was slower in the intervention group than that normally observed in Alzheimer patients. But there were no significant differences in cognitive decline at 6 and 12 months between groups. Which can mean that aerobic exercise is not more effective than stretching or light exercise.
It is interesting to note that one limitation of the study pointed out by the authors was the fact that the stretching group had inadvertently increased social interaction. These patients spent a lot of time with interventionists, in contrast to the cycling group where physical demand limited social interaction. Since exercise and social interaction have been shown to affect cognition in similar ways, this may be the reason why there was no significant difference in cognitive decline between the two groups.
This study supports the findings of previous studies and confirms the hypothesis that aerobic exercise can slow down the progression of disease by reducing cognitive decline in patients with Alzheimer’s disease. It also supports the increasingly accepted recommendation of a multifactorial approach for Alzheimer’s disease, including physical activity, social interaction, healthy diet, beside others.
Feel free to inform yourself here about the many lifestyle options for the prevention and/or treatment of dementia. Because one thing is clear: a healthy lifestyle seems to have a positive effect at every stage of the disease!
And if you would like to learn more about this exciting topic of ‘exercise and dementia’, please have a look here at ‘Knowledge stops dementia’.
Aerobic exercise reduces cognitive decline in patients with moderate symptoms of Alzheimer’s disease. However, its impact in disease progression doesn’t seem to be bigger than other lifestyle interventions like different modalities of physical activity and social interaction. A multifactorial approach is more likely to be the optimal treatment for dementia.
1. Erickson KI, Voss MW, Prakash RS, et al. Exercise training increases size of hippocampus and improves memory. Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):3017-22.
2. McGurran H, Glenn JM, Madero EN, Bott NT. Prevention and Treatment of Alzheimer’s Disease: Biological Mechanisms of Exercise. J Alzheimers Dis. 2019;69(2):311-338.
3. Baker LD, Frank LL, Foster-Schubert K, et al. Effects of aerobic exercise on mild cognitive impairment: a controlled trial. Arch Neurol. 2010 Jan;67(1):71-9
4. Yu F, Vock DM, Zhang L, et al. Cognitive Effects of Aerobic Exercise in Alzheimer’s Disease: A Pilot Randomized Controlled Trial. J Alzheimers Dis. 2021 Jan 26.