Introduction:

        As a person ages, it seems that their risk for developing Alzheimer’s Disease (AD) increases consistently and they will soon experience the symptoms of the disease. Although Alzheimer’s is notorious for being one of the leading causes of death in elders, it is not restricted to old people. In fact, AD is not a normal part of aging. Alzheimer’s is the leading cause of dementia, cognitive decline that interferes with daily functioning, and makes up for around sixty to eighty percent of all dementia cases. Alzheimer’s is a progressive disease, meaning that it does not immediately cause a person to forget everything. Instead, it starts off with small inconveniences that could be misinterpreted as carelessness. Gradually, the severity of Alzheimer’s increases, prohibiting a person from carrying out daily, normal tasks. The treatments that have been developed to counteract this disease only decelerates the rate at which AD progresses, rather than curing it completely. 

        Doctors can utilize various tools and methodologies to distinguish Alzheimer’s from another neurodegenerative disorder. In addition to procedural scans, different tests regarding memory, problem solving, counting, and language are used. Furthermore, blood and urine tests may be carried out to identify other possibilities and causes of the dilemma. When the presence of Alzheimer’s Disease is confirmed, patients are giving several prescription drugs that are approved by the U.S. Food and Drug Administration. However, none of these medications can stop the progression of AD. As of yet, when a person develops Alzheimer’s, medical professionals are able to help patients only to a certain extent.

 Anatomy of Alzheimer’s: 

        Alzheimer’s disease predominantly affects the nervous system through the neurons and brain. The neurons contain three parts: the cell body, dendrites, and axon. The cell body, the neuron’s core, carries genetic information and provides energy for nervous activity. The multiple dendrites within a neuron receive chemical signals from the axon terminal of other neurons and convert them into smaller electric impulses and transmit them towards the cell body. As mentioned, the axon enables electrical impulses to travel to other neurons. These three elements of a neuron function together to carry out communication, metabolism, and repair, remodel, and regeneration. In a healthy, aging brain, the brain shrinks. However, the brain retains its number of neurons and maintains function. With Alzheimers, neurons are injured and lose connection with other neurons, thus dying and causing a diminished quantity of active neurons. 

        Through various studies conducted, researchers have found that misfolded amyloid and tau proteins also add to the risk of one developing Alzheimer’s. Amyloid plaques are formed through the breakdown of a larger protein, amyloid precursor protein, and are considered to be toxic. Normally, tau proteins bind and stabilize microtubules, structures which help guide vital substances from the cell body to axons and dendrites. On the other hand, when Alzheimer’s is present, the abnormal changes in chemicals cause tau to disconnect from the microtubules, sticking to other tau, eventually forming tangles that harm the synoptic communication between different neurons (National Institute on Aging). The destructive amyloid and tau proteins cluster together to form plaques and tangles. In response to the tangles, the body fights back to preserve function and ability; however, this results in neurodegeneration. 

        Glia, or glial cells, are cells within the central and peripheral nervous systems that do not stimulate electrical impulses. Instead, they maintain homeostasis, form myelin, and protect as well as support neurons. Research suggests that the abnormal aggregation of glial cells, specifically microglia, may be directly related to chronic inflammation. Typically, microglia “cleans” the brain by ridding it of toxins and waste, enabling a healthy brain (National Institute on Aging). In a patient with Alzheimer’s, the patient’s microglia is unable to clear debris and plaque away, causing plaque to accumulate between neurons, thus hindering neuron communication. 

Causes of Alzheimer’s Disease

        The cause of Alzheimer’s disease is still a mystery for scientists around the world. So far, researchers have culminated age-related factors along with environmental, lifestyle, and genetic factors. Although old age has been linked to dementia the most, aging itself does not cause Alzheimer’s. The most predominant risk factor has its own reasons as to how Alzheimer’s and dementia can be connected to it. Primarily, the reduction in size in certain parts of the brain, inflammation, free radicals, and energy breakdown within cells are prime reasons Alzheimer’s is linked to old age. In a larger brain, the tolerance range for pathological damage before any sort of cognitive or critical decline is much greater than one of a more compact figure (Whitwell). As a person ages, their brain experiences changes that cause it to shrink, making it more susceptible for infirmities such as Alzheimer’s. Perneczky and other researchers tested the hypothesis by studying the association between brain atrophy and cognitive decline in numerous Alzheimer’s patients depending on brain circumference. The results were straightforward: intellectual performance of those with larger heads surpassed those with smaller ones. Inflammation occurs in the more vulnerable sections of an AD brain by disguising itself with the complexity of peripheral inflammatory responses. Thus, localizing itself with the cytokines and inflammatory mediators (Akiyama). 

        The hypothesis concerning the relation between a person’s environment and specific neurodegenerative disorders has been long considered by neuroscientists. The practical implications of this hypothesis is based upon a greater emphasis on healthier habits from early life, prevention, and a better understanding on how to approach treatment rationally based on the environment of a patient. In a study conducted with nearly three thousand research participants, the conclusion that having a healthier lifestyle and environment reduces the risk of developing AD or any neurodegenerative disease vastly was proven (Combination of healthy lifestyle traits may substantially reduce Alzheimer’s). Participants were given five healthy practices to follow during the experiment: participating in physical activity, refraining from smoking, consuming minimum alcohol, eating a balanced, healthy diet, and engaging in cognitive activities. Those who followed four to five behaviors while having a stable environment had their susceptibility to Alzheimer’s decrease by 60%. Although healthy habits can decrease the rate at which AD will develop, it is possible that one can develop it. The epidemic of Alzheimer’s thrives off of genetic inheritance (Genetics). Risk genes occur when the likelihood of developing a certain disease is increased; these genes indicate that there is an increased probability in having a disease, but it does not mean that the person is certain to develop it.

Alzheimer’s and Vascular Disease

        Not only do nervous system components get affected by Alzheimer’s disease, but vascular problems arise as well. These issues can range from beta-amyloid deposits in brain arteries to atherosclerosis to mini strokes. The reduced flow of blood and oxygen that travels to the brain stem from vascular problems. An example of how AD negatively affects the nervous and cardiovascular systems is through the destruction of the blood-brain barrier. The barrier protects the brain by preventing harmful substances and agents from entering while allowing necessary nutrients and factors, such as glucose, enter. A faulty blood-brain barrier prohibits needed factors from entering the brain, which then blocks the clearing of waste and toxic beta-amyloid and tau proteins. Inflammation results from the inability to void the brain of waste, leading to further complications and vascular difficulties in the brain. When vascular dementia is present, alterations in cognitive thinking and reasoning skills occur after a stroke, blocking major blood vessels in the brain. As a result of multiple minor strokes, mild inconveniences can worsen and lead to widespread damage in the brain (Alzheimer’s Association). Vascular brain changes are commonly associated with AD and Lewy body dementia. Researchers have noticed how the cause and consequence of vascular problems regarding the brain is Alzheimer’s and are now working on easy to develop ways to intervene in this cycle. 

Conclusion:

Recently, researchers have begun to delve and explore a variety of topics beyond the brain and neurons. They have begun to examine the vascular system, epigenetics, neuroproteins, synaptic health, immunity and inflammation, and metabolic dysfunction. Many of these ideas have previously been perceptive as unassociated with Alzheimer’s. For instance, epigenetics pertains to how a person’s genetics adapt to one’s environment, something many would see as unrelated to dementia. Nevertheless, exploring the role in which any aspect of the human body plays in the development in neurodegenerative diseases might help in having an explanation. A prime process researchers are attempting to enhance is the cell’s “garbage disposal” system. Alzheimer’s Disease is a malignant disease that affects a person in all aspects of their life. Many clinical trials and studies have been conducted in order to grasp the fundamental ideas of this mysterious disease, many without success.