Alzheimer's Disease

Alzheimer's disease (AD), also known simply as Alzheimer's, is a neurodegenerative disease that, in its most common form, is found in people over age 65.

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Approximately 24 million people worldwide have dementia of which the majority (~60%) is due to Alzheimer's. Clinical signs of Alzheimer's disease are characterized by progressive cognitive deterioration, together with declining activities of daily living and by neuropsychiatric symptoms or behavioral changes.

The most striking early symptom is memory loss (amnesia), usually manifest as minor forgetfulness that becomes steadily denser with illness progression, with relative preservation of older memories. It is the most common type of dementia.

Plaques which contain misfolded peptides called amyloid beta (Aβ) are formed in the brain many years before the clinical signs of Alzheimer's are observed.

Together, these plaques and neurofibrillary tangles form the pathological hallmarks of the disease.

These features can only be discovered at autopsy and help to confirm the clinical diagnosis.

Medications can help reduce the symptoms of the disease, but they cannot change the course of the underlying pathology. The ultimate cause of Alzheimer's is unknown.

Genetic factors are clearly indicated as evidenced by dominant mutations in three different genes have been identified that account for the small number of cases of familial, early-onset AD.

For the more common form of late onset AD (LOAD), ApoE is the only clearly established susceptibility gene.

All four genes can contain mutations or variants that confer increased risk for AD, but account for only 30% of the genetic picture of AD.

These four genes have in common the fact that mutations in each lead to the excessive accumulation in the brain of Aβ, the main component of the senile plaques that litter the brains of AD patients.

Dementia with Lewy bodies

Dementia with Lewy bodies is the second most frequent cause of hospitalization for dementia, after Alzheimer's disease.

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Current estimates are that about 60 to 75% of diagnosed dementias are of the Alzheimer's and mixed (Alzheimer's and vascular dementia) type, 10 to 15% are Lewy Bodies type, with the remaining types being of an entire spectrum of dementias including frontotemporal, Pick's disease, alcoholic dementia, pure vascular dementia, etc.

Dementia

Dementia is progressive decline in cognitive function due to damage or disease in the brain beyond what might be expected from normal aging.

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Particularly affected areas may be memory, attention, language and problem solving, although particularly in the later stages of the condition, affected persons may be disoriented in time (not knowing what day, week, month or year it is), place (not knowing where they are) and person (not knowing who they are).

Multi-infarct dementia

Multi-infarct dementia, also known as vascular dementia, is a form of dementia resulting from brain damage caused by stroke or transient ischemic attacks (also known as mini-strokes).