Alzheimer Disease 2

Explanatory Essay
Alzheimer Disease
There are two types of Alzheimer’s disease - early start and late start. In early start of Alzheimer’s disease, symptoms first appear before age 60. Early start of Alzheimer’s disease is much less common, accounting for only 5-10% of cases. However, it tends to progress rapidly. The cause of Alzheimer’s disease is not entirely known but is considerate to include both genetic and environmental factors.
Prior theories regarding the accumulation of aluminum, lead, mercury, and other substances in the brain leading to Alzheimer have been disproved. The only way to know for certain that someone had this disease is by microscopic examination of a sample of brain tissue after death. The brain tissue shows "neurofibrillary tangles" (twisted fragments of protein within nerve cells that clog up the cell), "neuritic plaques" (abnormal clusters of dead and dying nerve cells, other brain cells, and protein), and "senile plaques" (areas where products of dying nerve cells have accumulated around protein). Although these changes occur to some degree in all brains with age, there are many more of them in the brains of people with this disease. The obliteration of nerve cells (neurons) leads to a decrease in neurotransmitters (substances secreted by a neuron to send a message to another neuron). The correct balance of neurotransmitters is critical to the brain.
Early start of disease can run in families and involves autosomal dominant, inherited mutations that may be the cause of the disease. So far, three early onset genes have been identified. Late onset of Alzheimer, the most common form of the disease, develops in people 60 and older and is thought to be less likely to occur in families. Late onset of this disease may run in some families, but the role of genes is less direct and definitive. These genes may not root the problem itself, but simply boost the likelihood of pattern of plaques and tangles or other Alzheimer - related... [continues]

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