Dementia DDx. Office diagnosis of the four major types of dementia.

The prevalence of dementia increases with age from 1% at age 60 to about 40% at age 85. Four types of dementia--Alzheimer's disease, diffuse Lewy body dementia, frontotemporal dementia, and vascular dementia--account for 90% of all cases. The office-based physician can recognize these dementing illnesses in older patients by using existing consensus criteria. Differential diagnosis has an important bearing on patient management and prognosis, due to the potential value of treatment with some medications, possible drug toxicities in certain circumstances, and the complex care needs of patients and their families.