Differential diagnosis of dementia. The clinical process.

Dementia as a syndrome must be differentiated from nondementing conditions. Dementia itself must also be differentiated as to cause, as in certain cases reversible conditions may be responsible. This article examines the clinical process of such differentiation, providing a decision free for diagnosis and a summarizing algorithm for thinking through individual cases, with a focus on the most frequent cause of dementia, Alzheimer's disease. Also outlined are the stages of Alzheimer's disease, with the admonition that variations from the expected progression may represent a dementia diagnosis other than Alzheimer's disease or the co-occurrence of some other contributing factors.