Etiology of Alzheimer’s Disease

Alzheimer’s disease is a debilitating and, unfortunately, common illness that is characterized by extensive neuronal atrophy, memory loss, personality changes, and is the most common form of dementia. The atrophy is especially prevalent in the cerebral cortex and hippocampus. Patients are found to have severe loss of acetylcholine (a neurotransmitter) in these areas along with a corresponding loss of neurons in the basal nucleus and nearby cholinergic cell groups (Vanderah, Nolte, & Gould, 2016). With these being the general affected areas, there has been a variety of treatments to try and help with the disease.

Unfortunately, there is yet to be a cure, but some treatments have helped to temporarily slow the disease and help improve the quality of life while trying to deal with it.

Etiology

Currently, the exact cause of Alzheimer’s disease is unknown. Scientists and researchers are looking at two abnormal structures called plaques and tangles as being a possible cause in the damaging of neurons, leading to Alzheimer’s. Plaques are deposits of a protein fragment called beta-amyloid that builds up in the spaces between neurons. Tangles are twisted fibers of another protein called tau that builds up inside cells (Association, 2018). In a data analysis done by Cassie Mitchell at the Georgia Tech Institute of Technology, she researches the roles these proteins have in the disease. Mitchell found that the beta-amyloid may play less of a role, while phosphorylated tau (p-tau) may be more to blame. She identified that the p-tau has a much higher correlation with cognitive decline than the beta-amyloid. She also points out that the disease is multifactorial and likely needs to be treated from several angles to slow or stop the disease altogether (Huber, Yee, May, Dhanala, & Mitchell, 2017). It is important that we realize that the direct trigger to cause these proteins to act out of normal is unknown. The disease generally happens to older people and therefore could be a chronic effect of several factors.

Pathology

Alzheimer’s disease is a neurodegenerative disease that is the most common type of dementia. Dementia is characterized by memory loss, personality changes, and other impairments due to the degeneration. The Alzheimer’s Association lists the key features which include, impairment in memory, impaired daily activities, and shrinkage of the cerebrum, including the hippocampal region (Association, A., 2018). With the central nervous system degenerating you are likely to see other issues arise besides just dementia and thought impairment. Loss or impairment of motor control can be seen in the later stages.

Prognosis

Alzheimer’s typically progresses in three stages; early, middle, and late. These stages become subsequently worse in terms of cognitive decline and degeneration. As the progression continues, an increased accumulation of the beta-amyloid and p-tau proteins are seen. It is noted that just the accumulation of these proteins is seen in normal aging adults as well. It is likely a threshold point that includes inflammation and neuron degeneration before the symptoms of dementia and Alzheimer’s manifest themselves. Included pathologies are increased inflammation, brain atrophy, and altered mental state (Perrin, Fagan, & Holtzman, 2009). Other body functions will be affected in the later stages as the nervous system can no longer properly regulate them.

Epidemiology

At this point in time, the main risk factors for Alzheimer’s are old age and genetic susceptibility. While there are likely other causes, they are yet to be known for sure. The evidence is also pointing to other factors such as smoking, high blood pressure in middle age, obesity, diabetes, and cerebrovascular lesions. Currently, there is a prevalence of Alzheimer’s disease and dementia at 9.7% for people older than 70 years in the United States. Worldwide for people older than 60 years, that prevalence is at 3.9%. In the United States, there is an incidence rate of 15 people for every 1000 over the age of 65 to have Alzheimer’s disease (Qiu, Kivipelto, & Strauss, 2009). It is projected that by 2030 there will be 1 billion people over the age of 65. With old age being strongly correlated with the disease, it is thought that there will be a large increase in the number of people with Alzheimer’s. Understanding who is at risk and how to prevent the disease is at the forefront of research. With a large number of people reaching the age of highest risk, it is important to know this (Qiu, Kivipelto, & Strauss, 2009).

Treatments

There is no definitive cure for Alzheimer’s disease, but it is thought that prevention and early detection can help. Harvard health gives several steps to follow that may help prevent the disease or delay it. These steps include regular exercise, eating a Mediterranean diet, and get enough sleep. They also say that learning new things, connecting socially, and drinking a little alcohol may help as well. It is noted that there is not enough evidence that these prevent the disease but there is evidence that they prevent other chronic conditions. This being the case, these steps may help prevent Alzheimer’s (Harvard Health Publishing, 2017). The point of these preventative measures is multimodal. These activities provide a cognitive reserve, improve mental stimulation, increase anti-inflammatory, and promote brain plasticity and vascularization. All of this correlates with healthier aging and a lowered risk of dementia and Alzheimer’s disease.

The Alzheimer’s Association discusses several drug treatment options that target different chemicals and processes of the brain but point out that this only masks the symptoms. A considerable amount of research is being undertaken to find a cure or help ease the disease, but nothing substantial has been proven to be the key (Association, A., 2018).

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