ALZHEIMER’S DISEASE

ALZHEIMER’S DISEASE


General Description of Alzheimer’s Disease

Other names : Alzheimer’s presenile and senile dementia, senile dementia (Alzheimer type)
Alzheimer’s disease is a brain disorder named for German physician Alois Alzheimer, who first described it in 1906. Scientists have learned a great deal about Alzheimer’s disease in the century since Dr. Alois Alzheimer first drew attention to it.

Alzheimer's disease is the most common cause of dementia — the loss of intellectual and social abilities severe enough to interfere with daily functioning. In Alzheimer's disease, healthy brain tissue degenerates, causing a steady decline in memory and mental abilities. Alzheimer's disease is not a part of normal aging, but the risk of the disorder increases with age. About 5 percent of people between the ages of 65 and 74 have Alzheimer's disease, while nearly half the people over the age of 85 have Alzheimer's. Although there's no cure, treatments may improve the quality of life for people with Alzheimer's disease. Those with Alzheimer's — as well as those who care for them — need support and affe. [definition by Mayo Clinic]

Alzheimer's disease (AD) is a slowly progressive disease of the brain that is characterized by impairment of memory and eventually by disturbances in reasoning, planning, language, and perception. Many scientists believe that Alzheimer's disease results from an increase in the production or accumulation of a specific protein (beta-amyloid protein) in the brain that leads to nerve cell death; called amyloid plaque.

Other major hallmarks in the brain that are associated with the disease processes of AD are Neurofibrillary tangles (NFTs) and Loss of connections between neurons responsible for memory and learning.

Neurofibrillary tangles (NFTs), found inside neurons, are abnormal collections of a protein called tau. Normal tau is required for healthy neurons. However, in AD, tau clumps together. As a result, neurons fail to function normally and eventually die.
Loss of connections between neurons responsible for memory and learning. Neurons can't survive when they lose their connections to other neurons. As neurons die throughout the brain, the affected regions begin to atrophy, or shrink. By the final stage of AD, damage is widespread and brain tissue has shrunk significantly.

Prevalence

Prevalence of AD in populations is dependent upon different factors including incidence and survival. Since the incidence of AD increases with age, it is particularly important to include the mean age of the population of interest. In the United States, Alzheimer prevalence was estimated to be 1.6% in the year 2000 both overall and in the 65–74 age group, with the rate increasing to 19% in the 75–84 group and to 42% in the greater than 84 group. Prevalence rates in less developed regions are lower. The World Health Organization estimated that in 2005, 0.379% of people worldwide had dementia, and that the prevalence would increase to 0.441% in 2015 and to 0.556% in 2030. Other studies have reached similar conclusions. Another study estimated that in 2006, 0.40% of the world population (range 0.17–0.89%; absolute number 26.6 million, range 11.4–59.4 million) were afflicted by AD, and that the prevalence rate would triple and the absolute number would quadruple by the year 2050. As of September 2009, this number is reported to be 35 million-plus worldwide. The prevalence of Alzheimer's is thought to reach approximately 107 million people by 2050. [Wikipedia, December 24, 2009]

Principal Features

Insidious onset leading to progressive and permanent decline of all intellectual functions. Mood changes apathy, depression, irritability, anxiety, paranoia. Loss of recent memory, inability to recall facts of common knowledge, disorientation, confusion, all worse at night. Impaired attention, understanding, judgment. Loss of ability to think abstractly, to use language correctly, to calculate. Eventual gait disturbances, incoordination of movements. Social skills may be retained until late in course of disease. Course is from 3 to 20 years, with mean duration of 7 years.

Causes

Degeneration of nerve cell in the areas of the brain that control intellectual functions. Actual cause of degeneration in unknown. Scientists are not absolutely sure what role plaques and tangles play in Alzheimer’s disease. Most experts believe they somehow block communication among nerve cells and disrupt activities that cells need to survive.

Genetic predisposition appears probable; Alzheimer type dementia is four times more frequent among family members than in the general population. There is a history of previous head injury in 15% to 20% of cases. One common feature is a marked deficiency of the nerve transmitter acetyl-choline.

Drugs That Can Cause This Disease

No drugs cause true Alzheimer’s dementia. However, 3% of all dementias are drug induced. The following drugs can cause symptoms in the elderly that resemble Alzheimer’s disease : antidepressants, atropinelike drugs, barbiturates, benzodiazepines, butyrophenones, cortisonelike drugs, digitalis preparations, MAO inhibitors.

Drugs Used to Treat This Disease

No specific or truly effective drug treatment is available at this time. Ergoloid mesylates (Deapril-ST, Hydergine) are tried during the early stages to relieve symptoms; benefits are infrequent, negligible and fleeting.
Experimental drugs : choline, lecithin, physostigmine (none re curative or significantly beneficial). Nimodipine, a calcium channel blocking drug, is currently under study for human use. It has been shown to accelerate learning in aged rabbits.

Goals of Drug Treatment

Temporary improvement of alertness and memory. Relief of confusion, depression and behavioral disturbances.