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--A chronic, progressive, neurologic disorder characterized by degeneration of the neurons in the cerebral cortex and subcortical structures, resulting in irreversible impairment of intellect and memory.

Causes and Incidence The cause is unknown, although theories involving genetic links, neurotransmitter deficiencies, viruses, aluminum poisoning, autoimmune disease, and viruses have been advanced. Alzheimer's disease is the fourth leading cause of death among the elderly in the United States. Approximately 3% of individuals over 65 years of age show signs of the disease; the proportion climbs to 20% in those over 80 years of age. The incidence is higher in women.

Disease Process Selective neuronal cells, primarily those involved in the transmission and reception of acetylcholine, degenerate in the cerebral cortex and basal forebrain, resulting in cerebral atrophy of the frontal and temporal lobes, with wide sulci and dilated ventricles. Senile plaques and neurofibrillary tangles are present. The basic pathophysiologic processes accompanying the brain damage are unknown.

Symptoms

Early

Short-term memory loss, impaired insight/judgment, momentary disorientation, emotional lability, anxiety, depression, decline in ability to perform activities of daily living (ADLS)

Midcourse

Apraxia, ataxia, alexia, astereognosis, auditory agnosia, agraphia, prolonged disorientation, progressive memory loss (longand shortterm), aphasia, lack of comprehension, decline in care abilities, insomnia, loss of appetite, repetitive behavior, socially unacceptable behavior, hallucinations, delusions, paranoia

Late

Total dependence in ADLs, bowel and bladder incontinence, loss of speech, loss of individuation, myoclonic jerking, seizure activity, loss of consciousness

Potential Complications The end stage of Alzheimer's disease invites complications commonly associated with comatose conditions (e.g., skin breakdown, joint contractures, fractures, emaciation, aspiration pneumonia, infections).

Diagnostic Tests Definitive diagnosis can be made only through autopsy.

Clinical evaluation

Any of the above manifestations after depression, delirium, and other dementia disorders (e.g., head injury, brain tumor, alcoholism, drug toxicity, arteriosclerosis) have been ruled out; family history

Mental status examination

Decreased orientation, impaired memory, impaired insight/ judgment, loss of abstraction/ calculation abilities, altered mood

Computed tomography/magnetic resonance imaging

Brain atrophy; symmetric, bilateral, ventricular enlargement

Electroencephalogram

Slowed brain wave activity, reduced voltage

Treatments

Surgery

None

Drugs

Medications for treating specific symptoms or behavioral manifestations (i.e., antidepressants, stimulants, antipsychotics, sedatives); experimental drugs include cholinergic, dopamine, and serotonin precursors; neuropeptides; and transcerebral dilators

General

Structured, supportive, familiar environment; orientation and cueing program for daily tasks; safety program; family support and counseling; respite care; institutionalization when home care is no longer possible