Alzheimer's

Alzheimer's Description

Alzheimer's disease (AD), a neurodegenerative disease, is the most common cause of dementia and characterised clinically by progressive intellectual deterioration together with declining activities of daily living and neuropsychiatric symptoms or behavioral changes. The most striking early symptom of Alzheimer's is memory loss (amnesia), usually manifest as minor forgetfulness that becomes steadily denser with illness progression, with relative preservation of older memories. As Alzheimer's progresses, cognitive (intellectual) impairment extends to the domains of language (aphasia), coordinated movement (apraxia), recognition (agnosia) and those functions (such as decision-making and planning) closely related to the frontal lobe of the brain, reflecting extension of the underlying pathological process. This consists principally of neuronal (cell) loss (or atrophy), together with deposition of amyloid plaques and neurofibrillary tangles. Genetic factors are known to be important, and polymorphisms (variations) in three different autosomal dominant genes - Presenilin 1, Presenilin 2, and Amyloid Precursor Protein - have been identified that account for a small number of cases of familial, early-onset AD. For late onset AD (LOAD), only one susceptibility gene has so far been identified - the epsilon 4 allele of the APOE gene. Age of onset itself has a heritability of around 50%.

Alzheimer's History

The symptoms of the Alzheimer's as a distinct entity were first identified by Emil Kraepelin, and the characteristic neuropathology was first observed by Alois Alzheimer, a German psychiatrist, in 1906. In this sense, the disease was co-discovered by Kraepelin and Alzheimer, who worked in Kraepelin's laboratory. Because of the overwhelming importance Kraepelin attached to finding the neuropathological basis of psychiatric disorders, Kraepelin made the generous decision that the disease would bear Alzheimer's name.

For most of the twentieth century, the diagnosis of Alzheimer's disease was reserved for individuals between the ages of 45-65 who developed symptoms of presenile dementia, which was considered to be a more or less normal outcome of the aging process. In the 1970s and early 1980s, however, the name "Alzheimer's disease" began to be used, within and outside the medical profession, equally for individuals age 65 and older with senile dementia, and was eventually adopted formally for all individuals with the common symptom pattern and disease course in the psychiatric and neurological nomenclature.

Alzheimer's Clinical features

The usual first symptom noticed is memory loss which progresses from seemingly simple and often fluctuating forgetfulness (with which the disease should not be confused) to a more pervasive loss of recent memory, then of familiar and well-known skills or objects or persons. Aphasia, disorientation and disinhibition usually accompany the loss of memory. Alzheimer's disease may also include behavioral changes, such as outbursts of violence or excessive passivity in people who have no previous history of such behavior. In the later stages, deterioration of musculature and mobility, leading to bedfastness, inability to feed oneself, and incontinence, will be seen if death from some external cause (e.g. heart attack or pneumonia) does not intervene. Average duration of the disease is approximately 7-10 years, although cases are known where reaching the final stage occurs within 4-5 years, or up to 25 years.

Alzheimers Diagnosis

The diagnosis is made primarily by clinical observation and tests of memory and intellectual functioning over a series of weeks or months, with various physical tests (blood tests and neuroimaging) being performed to rule out alternative diagnoses. No medical tests are available to conclusively diagnose Alzheimer's disease pre-mortem, however.

Interviews with family members and/or caregivers can be extremely important in the early phases as well, as the sufferer him/herself may tend to minimize his symptomatology or may be being observed on a day when his/her symptoms are in temporary dormancy.

Initial suspicion of dementia may be strengthened by performing the mini mental state examination, after excluding clinical depression. Psychological testing generally focuses on memory, attention, abstract thinking, the ability to name objects, and other cognitive functions. Results of psychological tests do not easily distinguish between Alzheimer's disease and other types of dementia but can be helpful in establishing the presence of and severity of dementia. They can also be useful in distinguishing true dementia from temporary (and more treatable) cognitive impairment due to depression or psychosis, which has sometimes been termed "pseudodementia".

While expert clinicians who specialize in memory disorders can now diagnose AD with an accuracy of 85-90%, a definitive diagnosis of Alzheimer's disease must await the autopsy.

Recommended reading: The Mind Killer Defense

Pathology

Microscopy
There are several changes found in the brain in AD (in order of appearance):