28. Dementia

Dementia is an acquired disorder involving the deterioration of various cognitive functions with intact consciousness. Behavioural problems and emotional changes occur sooner or later in any form of dementia. The most common cause of dementia is Alzheimer’s disease (AD). Dementia can also be caused by vascular brain damage. Frontotemporal dementia is characterized mainly by changes in behaviour. Lewy body dementia (LBD) involves a combination of dementia and parkinsonism. Several atypical forms of parkinsonism (sect. 27.2) may be associated with dementia. These may precede motor symptoms and other symptoms. Creutzfeldt-Jakob disease (Creutzfeldt-Jakob disease, CJD) is a rapidly progressive, fatal disorder. Dementia can develop in the late stages of AIDS and syphilis. This chapter explores the dementia spectrum and the various disorders that can cause dementia. The latter range from common (AD; sect. 28.5) and vascular dementia (sect. 28.6) to very rare (CJD; sect. 28.10) and paralytic dementia in syphilis, which used to be common but is now very rare (sect. 28.11). Chapter 8 deals with our basic understanding of higher cerebral functions. There are also links to Chap. 27, concerning syndromes with movement disorders.