Alzheimer’s disease (AD) is a progressive type of mental disorder. Although it occurs rarely in middle age, the prevalence increases in old age to more than 20% in adults aged 80 years and older.

Symptoms
Loss of short-term memory is typical. Other symptoms include impaired judgment, mood disorders, loss of insight, and change in personality. As the illness progresses, early symptoms are commonly followed by additional behavioral symptoms (delusions, hallucinations, and agitation) and difficulty swallowing, controlling bladder and bowel functions, and maintaining mobility.

Diagnosis
The diagnostic criteria includes:
• Multiple defects in mental functioning.
• Decline in social or occupational function, or both.

Before the diagnosis of Alzheimer's is made, it must also be excluded that other causes of the symptoms are not present. Such causes may include delirium, major depression, multi-infarct dementia, alcohol-related dementia, Parkinson’s disease, Pick’s disease, and AIDS-related mental disorder. Extreme caution is required when diagnosing a confused older adult as having a nonreversible dementia. Delirium should always be excluded. There is also a long list of potentially reversible conditions that can present as a chronic deterioration of mental function, including adverse effects from medications and alcohol, depression, thyroid disease, hypoxemia, subdural hematoma, normal-pressure hydrocephalus, and intracranial neoplasia.

Risk Factors
Risk factors for AD include advancing age, family history, and the presence of Down’s syndrome.

Evaluation
A thorough patient history and a careful physical examination (emphasizing the neurologic examination) are essential for determining the possible cause for chronic confusion. The diagnosis of AD is made by exclusion; no clinical feature or commonly available diagnostic test can confirm the diagnosis. The most important historic information is the duration of symptoms. It is helpful to use an objective test for mental status. However, well-educated, intelligent adults can score near normal on a screening test and still have a progressive dementia.

Treatment
Specific treatment of the memory loss associated with AD is currently limited to the use of tacrine (Cognex). Chronic management of AD includes office visits at 4- to 6-month intervals. Associated depression can be treated with a low-anticholinergic antidepressant. Anxiety and agitation can usually be managed through environmental adjustments and the avoidance of caffeinated beverages. Benzodiazepines should be used cautiously.

Families and caregivers of AD patients can benefit from regular counseling.