Disability in dementia: assessment, prevention, and rehabilitation.

Dementia involves cognitive impairment sufficient to interfere with daily living. Most cases of dementia are due to Alzheimer's disease or cerebrovascular disease. Surveys show that dementia is one of the major causes of disability in the elderly, affecting personal care, everyday cognitive activities, and social behaviour. Several instruments relying on informant reports or behavioural observation have been developed to assess these various components of disability in dementia. Prevention of dementia would make a major contribution to the postponement of disability in old age. In principle, this could be achieved by modifying risk factors for Alzheimer's disease or vascular dementia. There is presently scope for the prevention of vascular dementia, but risk factors for Alzheimer's disease are not sufficiently understood. The paper discusses how, where dementia has already developed, programmes involving cognitive training or environmental redesign can help to maintain skills and reduce behavioural disturbances.