The differential diagnosis of dementia.

Dementia is misdiagnosed in up to 15% of cases referred for further assessment. Real or apparent cognitive impairment is usually a prominent clinical feature of the most common differential diagnoses, including normal aging, depression, nonaffective psychoses, delirium, and amnestic syndromes. To date, no practical biological marker exists to aid in diagnosing dementia. However, other conditions that are frequently amenable to treatment can usually be differentiated from dementia following detailed clinical assessment and the use of appropriate diagnostic criteria. Some considerations that aid in distinguishing dementia from other conditions include: rates of onset and progression; duration of symptoms; fluctuations in the intensity and pattern of symptoms; the pattern and extent of cognitive impairment and its effect on activities of daily living; alterations in the level of consciousness; the presence of affective and psychotic symptoms; past medical, family, and psychiatric history, including information about current medications, substance abuse, and premorbid personality.