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Course of Alzheimer's Disease

Alzheimer's Disease is the most common form of dementia, accounting for about 50-75% of all cases of dementia [ref]. Although in rare cases the disease can start as early as in one's 40's or 50's, usually it does not start before the sixth decade and becomes more and more common with increasing age [ref]. For example, whereas about 1% of individuals ages 70-74 will be diagnosed with Alzheimer's every year, this figure jumps to 8% among those above 85 years of age [ref], and close to 30% of individuals above age 95 have the condition [ref].

Alzheimer's Disease begins insidiously, usually following on the heels of Mild Cognitive Impairment. In the first stages of the illness, known as Mild Dementia (MMSE score of >18 or FAST stage 4), individuals start to have difficulty managing their instrumental activities of daily living, such as balancing a checkbook or preparing a meal with various dishes, and they will have trouble remembering significant information, such as directions to known places, certain people's names, and where they placed objects.

In Moderate Dementia (MMSE score of 1018 or FAST stage 5), individuals have difficulty with basic activities like preparing simple meals, choosing proper attire, or performing basic household chores. If left to wander unaccompanied they can get lost even in familiar neighborhoods, and their ability to recall recent events or identifying people will be significantly impaired.

In Severe Dementia (MMSE score of less than 10 or FAST stages 6 and 7) individuals lose the ability to perform even basic hygienic activities like bathing and toileting and require close supervision and constant assistance. Eventually they lose the ability to communicate altogether and become bed bound. Death occurs on average about 8 to 10 years after the onset of symptoms, and is usually due to infectious diseases.

Psychiatric syndromes are a very common feature of Alzheimer's Disease [ref]. In the early stages, depression, anxiety, irritability, apathy, and subtle personality changes tend to occur. In the later stages, psychosis and agitation are more common.

 

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Causes

Cognitive and Functional Loss