The effects of aerobic exercise and physical activity on progression of Alzheimer's disease and mild cognitive impairment

This abstract will provide a brief overview of the following literature review. Alzheimer’s disease (AD) is the most common cause of dementia, and is a rapidly growing public health concern, as an increasing number of the world’s population is living well beyond 65 years of age. Alzheimer’s Disease is a progressive neurodegenerative condition, first presenting with mild memory impairment, and advancing over the course of years to profound memory loss, complete immobility, lack of speech and facial recognition. Currently, only palliative treatments are available to delay the progression of the disease, and lessen the severity of the cognitive impairment. However, until a cure is available, researchers and physicians have turned their attention to alternate therapies, one of the most important being exercise. Research efforts have now turned to examining the relationship between the positive physiological responses to exercise, and attenuation of the classic neurodegenerative patterns in patients with AD. The current study examined the effects of aerobic exercise, strength training and resistance-based exercise, and multimodal exercise (containing both of the aforementioned exercise modalities) on the physical and mental/cognitive health of patients with mild cognitive impairment (MCI) and AD. Thus far, exercise therapy has proven to be of great potential value as a supplement to pharmacological treatment, as well as a stand-alone prescription for patients with a milder form of cognitive impairment due to the onset of a neurodegenerative condition. The benefits can be grouped into two categories, cognitive and physiological. The effects on cognitive function range from improved memory to increased independence in activities of daily living, and the physiological effects range from improved clearance of amyloid beta plaques in the brain, to reduction of neuroinflammatory processes. The available research on this subject is extensive, covering a variety of exercise modalities at different intensities, and taking into consideration effects on individuals with MCI, early AD, and advanced AD. The general consensus is that continued, long-term adherence to an appropriate exercise routine can delay cognitive decline, and help patients with neurodegenerative diseases to live independently for a longer period of time. The improvements in cognition, memory, immediate recognition, and other related cognitive functions are mostly attributed to the heightened health of the brain tissue and neural circuitry due to exercise. Exercise (mainly aerobic) enhances cerebral blood flow, improves cardiovascular health, reduces the risk for type 2 diabetes mellitus, and has several other important effects that prevent the formation of pathological biomarkers of AD and promote neurogenesis. Atrophy of regions such as the hippocampus, amygdala, and cerebral cortex can be prevented, and reversed to a certain extent, as a result of long-term exercise therapy. The results of current research could assist physicians and caregivers to provide the appropriate type and intensity of exercise to patients with early, intermediate, and advanced stages of Alzheimer’s disease. Proactive exercise therapy for individuals with a known family history of neurodegenerative disease may help to maintain brain volume, specifically in the hippocampus, and reduce the risk of severe cognitive impairment. Future directions for research include examining the combined effects of pharmacological treatment and exercise therapy, and determining the average amount of time by which exercise delays the progression of early stage cognitive impairment to advanced impairment. Key Terms: aerobic exercise, Alzheimer’s disease, amyloid plaque, hippocampus, mild cognitive impairment, neurodegeneration, neurofibrillary tangl