The dementias associated with cortical syndromes are described in one chapter: Alzheimer’s, frontotemporal degeneration, disseminated Lewy body disease, and the prion dementias, along with their distinct clinical picture, epidemiology, and pathology/etiology. In the following chapter, the diseases associated with a subcortical or mixed pattern of dementia are described: Parkinson’s, progressive supranuclear palsy, Huntington’s, normal pressure hydrocephalus, multiple sclerosis, HIV and AIDS, cerebrovascular disease, depression-induced cognitive impairment, traumatic brain injury, and various toxicities. The authors stress the importance of making a specific diagnosis of the cause of dementia because this conveys important knowledge about prognosis and, therefore, more effective treatment.