By Wendi Zheng
What is Alzheimer’s Disease, and How Might Exercise Help?
Alzheimer’s Disease (AD), the common cause of dementia, affects tens of millions of people worldwide and is expected to triple by 2050. AD is not only memory loss; the devastating disease chips away at the patient, causing behavior changes, impairing communication, and eventually taking away one’s ability to perform simple tasks, until they near total dependency on a caretaker’s assistance. Although the main risk factor for AD is old age, environmental factors such as climate change and air pollution also increase the likelihood of developing the disease, which may prove to be increasingly problematic in the future. Scientists have long sought to understand this disease and find effective treatments or, better yet, a cure. However, before a cure emerges, it is important to find and practice methods of prevention, especially those which are lifestyle changes, able to be implemented regardless of one’s economic status or where one lives. Recent research has suggested physical exercise to be one of the greatest aids in preventing AD.
Although there have been limited trials, which makes it difficult to definitively prove that exercise is an effective preventative measure, there is moderate evidence that exercise can be a useful tool for lowering the risk and delaying the progression of Alzheimer’s. Alzheimer’s is often seen as a neurological disease, but it is localized in other organs in the body outside the brain, including the cardiovascular system, gut microbiome, liver, and kidney. Therefore exercise, which helps the human body’s adaptation, can effectively improve cognition and contribute to neuroprotection. Exercise has also been seen to reduce Aβ concentrations, which are misfolded proteins that aggregate and clump, forming plaques in the extracellular region of brain cells, unique to AD.
Older Adults Who Exercise Are at Reduced Risk of AD
Low physical activity levels in older adults have been shown to lead to greater risk levels for AD. A study identified seven potentially adjustable risk factors for AD, through examining meta-analyses. In the study, low physical activity was the highest attributable risk. Another study examined 163,000 non-psychotic participants, and correlated the least relative risk of dementia to those in the highest physical activity category. The study also found that physical activity can lower the risk of dementia and AD by twenty-eight and forty-five percent, respectively. Another study conducted on the German population found those who regularly exercised performed better than those with low physical activity in neuropsychological tests and were at lower risk for AD. Even low-intensity activities, including walking, have been shown to aid in the preservation of cognitive abilities; women who walked more at baseline showed less cognitive decline after six to eight years. Thus, these studies show that those who exercise more while at baseline lower their risk of developing AD symptoms and experiencing cognitive decline, even years after baseline.
Aerobic Exercise and the Prevention of AD
Metabolic impairment in the central nervous system and the cardiovascular system has intertwined with AD and may be the cause of certain AD-induced cardiovascular disorders. The pathways of the cardiovascular system caused by endurance exercise have been shown to be similar to certain pathologies of AD. Thus, endurance exercise, which has been shown to lower blood pressure and decrease other cardiovascular risk factors, can be beneficial to those at risk for AD. By exercising regularly, cells gain better endurance to oxidative stress, vascularization, energy metabolism, and neurotrophin synthesis. These are all crucial to a cell’s capability in neurogenesis, memory improvement, and brain plasticity, which are all defenses to cognitive decline and risk for AD.
One study found that older adults who participated in a one-year exercise program that considered three 40-minute sessions a week had increases in the size of their hippocampi and in their spatial memory, suggesting that exercise intervention for older adults can improve their cognitive health and delay brain aging. Other research groups confirmed these findings; one study found six months of hour sessions three days a week of aerobic exercise was able to increase brain size. These results were not matched by the group that participated in toning and stretching exercises with no aerobic exercise. However, it is important to note that, possibly due to the training intensity, duration, and frequency, other studies have also found neutral results when examining aerobic exercise as a method of cognitive function improvement or reserve.
Discussion
Regardless of conflicting results, many studies have shown statistically positive results that make us optimistic that exercise-related intervention methods may be worth implementing. Exercise is an aspect of our lives that can be worked into an individual’s lifestyle without medication or advanced technology. It is an accessible and affordable way to prevent and treat AD. It should also be stressed that it is important that older adults take AD seriously and are proactive in taking preventative measures; prevention is the best way to fight any disease.
Although exercise has been shown to be possibly helpful in reducing the risk of AD and promoting cognitive reserve, it is unfortunately not a guarantee against AD. One may still develop AD symptoms, and the exact causes of AD are extremely complex, requiring further research. However, even if one does begin to develop symptoms, it is crucial, if not more, that they take measures in delaying or preventing the progression of AD and its symptoms. AD is more manageable at earlier stages, and therefore it is important that symptoms do not worsen. The methods of exercise intervention can still be helpful in alleviating symptoms and improving cognition in patients with AD.
Lastly, I propose that older adults be informed and directed by physicians on these possible ways of preventing AD, and be instructed to continue following these methods if symptoms develop. Along with being a more accessible and less expensive method of AD prevention, exercise is also unlikely to have negative side effects or bring potential harm, unlike other forms of treatment. By informing adults at risk of these possible preventive measures and lifestyle changes, we can benefit public health and reduce the number of AD patients and lower the estimations of patients in the future, which, in turn, gives us time to find better, more effective interventions and treatments, as well as a potential cure.
