Clinical subtypes of Alzheimer's disease.

Alzheimer's disease (AD) can present as a variety of clinical profiles. Although the most common presentation is that of a progressive amnestic disorder with subsequent involvement of other cognitive functions and personality alterations, there are numerous other clinical profiles. AD can present as a focal cortical degenerative syndrome with the clinical features dependent on the regions of the brain involved. Some of these syndromes include disturbances of language, visuospatial skills, attentional functions, executive processes and praxis. The neuropathological substrate of these disorders is variable and can include AD. Recently, the Lewy body variant of AD has been described. Finally, other modifying features that affect the progression of AD, such as extrapyramidal symptoms and myoclonus, are also discussed. Although the progressive amnestic form of AD is the most common presentation, other variations on the clinical syndrome can be important to identify because they may have implications for prognosis and treatment.