Alzheimer's disease: making the diagnosis.

Alzheimer's disease accounts for about 60 percent of dementia cases. Misdiagnosis of the treatable dementias can have devastating results. Pseudodementia accompanying major depression and chronic cognitive dysfunction due to psychoactive drugs are among the most commonly missed diagnoses. Although cortical atrophy is regularly found on computed tomographic scans in Alzheimer's disease, it is not necessarily diagnostic. A relatively distinct onset of cognitive impairment is not characteristic of Alzheimer's disease.