It can be difficult to fit exercise into busy schedules, especially for college students who always seem to have exams and deadlines approaching. However, exercise provides many neurological benefits, such as sharpened cognitive skills, reduced anxiety and depression, improved mood, and better sleep. Aerobic exercise in particular can help prevent neurological pathologies such as Alzheimer’s disease (AD) and serve as a potential treatment for people with early stages of AD [1]. After analyzing the results of several studies, it was found that physical inactivity was the greatest modifiable risk factor for AD in the United States [2].  Since AD affects almost 10% of individuals over the age of 65 in the United States, the value of aerobic exercise as a possible form of prevention cannot be overlooked [3].

Alzheimer’s Disease

Alzheimer’s disease is a neurodegenerative disorder that results in memory loss, difficulty problem-solving, and personality changes. As the disease progresses to later stages, it is marked by confusion, hallucinations, and failure to recognize familiar people and objects and remember crucial information. Ultimately, the individual loses the ability to communicate, swallow, and sustain vital functions as the disease spreads throughout the brain. The rate of disease progression varies greatly, but patients usually survive only three to 10 years after diagnosis [4]. There is currently no cure for Alzheimer’s disease, but there are several treatments that can be used to slow the progression of the disease. Initially, behavioral therapies are often used to treat neuropsychiatric symptoms such as agitation and behaviors such as hoarding [5]. Alternatively, pharmacological management of AD may include the use of antipsychotic medications, which alter the level of chemicals in the brain, such as dopamine and serotonin, that regulate mood and emotion. This can help treat symptoms such as aggression and hallucinations that are caused by an imbalance of these chemicals. However, these drugs must be used carefully because they may cause several negative side effects, such as cognitive decline, drowsiness, unsteady gait, and increased risk of stroke [5].

Alzheimer’s disease is characterized by the accumulation of beta-amyloid plaques. These plaques, which normally play a role in neuronal repair, become toxic when an enzyme fails to cut the precursor protein properly. AD is also marked by tangles composed of abnormal tau protein. Tau protein stabilizes microtubules, which are important for the transport of substances within cells, in neurons [6]. According to the cascade hypothesis of AD, the build-up of beta-amyloid plaques disrupts signaling between neurons and induces a chain reaction that results in a toxic form of tau protein,forming tangles. Over time, the accumulation of plaques and tangles impedes neuronal communication and nutrient supply, leading to neuronal death and reduced brain volume in regions such as the hippocampus, entorhinal cortex, amygdala and frontal lobe. The hippocampus is responsible for memory; consequently, AD patients suffer from memory loss. Patients often additionally have trouble planning and navigating since the entorhinal cortex governs spatial and temporal information. Since the amygdala and frontal lobe are heavily involved in emotional processing, decision-making, and personality, patients frequently exhibit poor judgment and behavioral changes [6] [7]. Thus, it is clear that the effects of Alzheimer’s Disease are wide-ranging. Given the prevalence of Alzheimer’s, the devastating consequences of the disease, and the profound negative effects of many existing treatments, prevention is crucial. One possible method of prevention that may be helpful is through regular exercise.

The Role of Exercise

Exercise can potentially serve as a form of protection against AD in many ways, such as by raising hippocampal volume and cortical thickness, regulating mitochondrial function, and improving overall mental health.

Exercise significantly boosts hippocampal volume through the synthesis of neurotrophic factors, which are proteins that promote neuron growth and survival [8]. Neurotrophic factors help facilitate communication between neurons. They may additionally help combat the negative effects of AD since they are important for learning and memory. Research suggests that aerobic exercise can also slow down the progression of existing Alzheimer’s Disease in patients without having many of the adverse effects of medications. A six-month trial analyzed the effects of 150 minutes of aerobic exercise per week to a non-aerobic stretching and toning intervention in patients with early-stage AD. Cardiorespiratory measures and brain MRIs demonstrated that patients in the aerobic exercise group exhibited less hippocampal atrophy and had improved memory function compared to the non-aerobic group [9].  Aerobic exercise has also been shown to increase cognition and thus may prevent the decline in mental abilities that is associated with AD. An increase in the thickness of the cortex, the outer layer of the brain associated with executive function and intellectual processing, was observed in young adults who engaged in aerobic exercise four times a week [10]. Regular aerobic exercise may help combat neuronal death, which results in cortical thinning, and preserve cognitive abilities in Alzheimer’s patients. The participants who exercised frequently also had higher maximum rates of oxygen consumption; efficient delivery of oxygen to brain cells helps increase their proliferation and longevity. These findings suggest that cardiorespiratory fitness is essential for brain health.

On the cellular level, physical exercise promotes mitochondrial function, which may serve as another mechanism for neuroprotection. Mitochondria, the organelles that help convert glucose to cellular energy, are important for brain cells, which have a high energy demand. Mitochondria also play a role in important processes such as signaling cell death and regulating calcium levels. Studies have demonstrated that the accumulation of beta-amyloid in mitochondria lead to their dysfunction; the toxic form of tau protein is more likely to be expressed when there is improper mitochondrial transport along thin filaments like microtubules. Furthermore, mitochondrial dysfunction is associated with greater production of reactive oxygen species, which contribute to oxidative stress, aging, and chronic diseases [11]. Thus, moderate aerobic exercise can regulate mitochondria and protect the sensitive tissues in the brain from oxidative damage [12].

The mental health benefits of exercise are tremendous as well. Alzheimer’s disease patients often suffer from sadness and anxiety; depression and social isolation are two of the major risk factors for developing AD. One trial showed that four months of moderate-to-high intensity physical exercise in patients with mild AD reduced neuropsychiatric symptoms, such as delusions and aggression, without the side effects of interventions such as drugs [13]. Exercising also boosted physical performance in AD patients, which may help postpone the difficult loss of self-efficacy that is associated with later stages of the disease [14]. Aerobic exercise of any intensity can greatly improve mood and help treat depression by releasing endorphins, our body’s natural pain killers [15]. These feel-good molecules can help lower anxiety and stress in both healthy subjects and those with AD [16]. Exercise has the added benefit of improving self-confidence and decreasing stress, which can be valuable for patients who are coping with Alzheimer’s [17].

Exercise for your Brain

Researchers are also investigating the effects of group workouts that combine aerobic exercise with social interaction, which is known to decrease depression and AD risk, for more significant results . One such study examined the effects of a collective exercise program on AD patients in nursing homes. Each group comprised of an average of five individuals with mild to severe AD who participated in aerobic, strength, and flexibility training for one hour twice a week. Members of the exercise group demonstrated a significant decrease in their deterioration in ability to perform activities of daily living such as eating and bathing, compared to the control group [18]. Group exercise helps form interpersonal connections that reduce loneliness and build community, while also having the positive effects of aerobic activity.

There is a clear connection between exercise and improved mood, physical well-being, mental function, and memory. Leading a sedentary lifestyle is significantly associated with a higher risk of developing Alzheimer’s disease and several other chronic conditions. Exercise has a neuroprotective effect that can help prevent AD by reducing hippocampal death, promoting mitochondrial fitness, improving mood, and sharpening cognitive abilities. Individuals who suffer from early-stage AD may additionally benefit from aerobic exercise as an intervention to slow disease progression without the deleterious effects of medications. Further research is needed to determine the most effective subtype and duration of exercise for healthy patients and those with mild AD for the greatest neurological benefits, and it is important to consider factors such as sex and age when developing exercise regimens. So, next time you’re at the gym, remember your brain will thank you later!


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