Alzheimers Disease Causes And Consequences In Cognitive Functioning Biology Essay

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Alzheimer's disease is considered common cause of mental deterioration, or dementia. This disease is progressive and affects the brain, with a gradual loss of memory and vital functions, leading to the patient to disability and finally to the death (Pinel, 2009). Alzheimer's disease is not the only cause of dementia. For this reason, its diagnosis is very difficult due that its behavioral symptoms could be similar to other diseases that affect the cognitive functioning (Pinel, 2009). This paper explores causes, symptoms, and consequences in cognitive functioning due to Alzheimer's disease in human beings. In addition, this paper contains information about available medications, treatments, and prognosis in this debilitating disorder that affect to many persons around the world.

Keywords: Alzheimer's disease, vascular dementia, cognitive deficits, differential diagnosis

Alzheimer's Disease: Its Causes and Consequences in Cognitive Functioning

Alzheimer's disease is a degenerative process of the brain of unknown cause that produces impaired cognitive functioning, loss of memory, and dementia, resulting in patients' disability, and finally their death (Pinel, 2009). This disease was first depicted in 1907 by Alois Alzheimer, who described the case from a 51 years' old woman who was exhibiting symptoms of progressive dementia for a lapse of almost 5 years (Sadock & Sadock, 2003). The Alzheimer's disease typically affects to persons with are over 65 years of age, although this disease can affect younger individuals also (Pinel, 2009). On its initial stage, Alzheimer's disease shows some notable warning signs. The affected person exhibits onset of impairments in memory and other executive functions (Pinel, 2009), In more advanced states, the patient presents with disorientation to time and place, notable changes of personality affecting mood and behavior, problems with speech (aphasia), loss of the ability to execute or carry out learned purposeful movements (apraxia), inability to recognize people or objects even when basic sensory modalities such as vision, are intact (agnosia) (Mathias & Burke, 2009). The average of life for Alzheimer's disease patients is approximately 8-10 years (American Psychiatric Association [APA], 2000).

For its characteristics, Alzheimer's disease presents a challenge for the researcher, due to a combination of factors, such as of genetic predisposition, individual life style, and age, that plays an important role in the onset and progression of the disease (Hamacher, Meyer, & Marcus, 2007). In spite of these factors in the actuality there is a better understanding about the molecular basis of the amyloid beta, which is responsible of the deposits of senile plaques in the brain, remarkable sign of brain's deterioration in patients with Alzheimer's disease (Levinoff, 2007). Microscopic findings exhibit in addition to senile plaques, the presence of neurofibrillary tangles, neuronal loss (with remarkable signs of deterioration in the cortex and hippocampus), synaptic loss (more than the 50% located in the cortex), and granulovascular degeneration in the neurons (Sadock & Sadock, 2003). In spite that the causes of Alzheimer's disease are associated with senile plaques and neurofibrillary tangles (NFTs), the relationship between these two neuropathologic lesions is unknown (Dickson, 2004). In addition, it is not clear if cognitive impairment in Alzheimer's disease is linked to the amount of amyloid deposited in the brain or the number of senile plaques as it is to the amount of abnormal tau protein in the brain and the density and distribution of NFTs (Nelson, Braak & Markesbery, 2009).

The negative consequences in cognitive functioning and memory in Alzheimer's patients in comparison with patients with mild cognitive impairment due to other factors, is really impressive. Alzheimer's disease produces a decline in cognitive functioning 4 times faster in comparison with the decline of cognitive functioning to healthy people (Gandey, 2010).Other symptoms of Alzheimer's disease are related to extrapyramidal motor signs, such as rigidity, postural changes, and slowness of movement (bradykinesia). These motor dysfunctions are the main obstacles for the patients and their caregivers, being the main cause of institutionalization and death for the Alzheimer's patients (Press, 2004). Social interaction has, of course, a notable decline in patients with Alzheimer's disease in comparison with healthy older adults, due to that this disease has an limiting effect on emotional processing (Mowat, Stephen, Phillips, Scott, & Henry, 2010).

Different alternate theories have been elaborated to try to explain the causes of Alzheimer' disease, such as aluminum toxicity, excessive stimulation by the transmitter glutamate that may cause damage to neurons, abnormality in the regulation of membrane phospholipid metabolism, resulting in an increment of rigidity in the membranes (Sadock & Sadock, 2003). At this moment, there is not a biological marker able to be identified as a diagnostic of dementia of the Alzheimer type in a living person (APA, 2000). Risk factors for Alzheimer's disease have been associate with increasing age, low educational level, and the apolipoprotein E ε4 allele, whereas a reduced risk of Alzheimer's disease has been linked to use of non-steroidal anti-inflammatory drugs, wine and coffee consumption, and regular physical activity (Lindsay et al., 2002). In addition, Lindsay et al. (2002) argued that "no statistically significant association was found for family history of dementia, sex, history of depression, estrogen replacement therapy, head trauma, antiperspirant or antacid use, smoking, high blood pressure, heart disease, or stroke" (p.445).

There is no known cure for Alzheimer's disease, and it is considered terminal. Drugs used to treat this disease only are able to control the symptoms or delay its progression (Pinel, 2009). Cholinesterase inhibitors could be of help in increasing levels of acetylcholine in the brain, helping to improve the memory. These medications were a standard therapeutic approach to the treatment of Alzheimer's disease in the first times. However, many patients have not received the expected benefits or have discontinued its use because they have proven ineffective to alleviate the symptoms of the disease (Pinel, 2009). Other drugs known as partial glutamate antagonists can also be used to delay the progression and symptoms of this disease. Glutamate is a neurotransmitter that is able to cause enhanced activity in neurons. For this reason, this neurotransmitter could eventually lead to the progressive deterioration of cells. Partial glutamate antagonists are designed to decrease the level of cells' sensitivity to glutamate, so they are able to reduce its negative effects (Mucke, 2009).

In spite that Alzheimer's is a progressive and terminal disease, an adequate management could alleviate the suffering of the patients and their families. The adoption of healthy measures, such as a healthy diet, exercising, control of cholesterol and blood pressure are helpful alternatives to decrease the risk of Alzheimer (Mucke, 2009). Exercising regularly is a factor important to increase and maintain the memory centers of the brain. Reading, puzzles, brain games, any kind of activity mental has been associated with lower risk of brain's deterioration. Social activity, sharing your time with others is another strategy to keep this disease away (Mucke, 2009).

The actual scientific research, with new and more advanced resources, is opening new doors to the cure of many diseases that today are affecting many people. Alzheimer's disease will be one of them.