Outcome measures for the study of activities of daily living in vascular dementia

Decline in functional abilities is a major component of the dementia syndrome. The definition of dementia in the International Classification of Diseases (10th rev.) requires a cognitive impairment sufficient to impair personal activities of daily living (ADL). The Diagnostic and Statistical Manual of Mental Disorders (4th ed.) also requires cognitive deficits sufficiently severe to cause impairment in occupational or social functioning and must represent a decline from a higher level of functioning. However, the term disability is more appropriate than impairment to describe a loss in activities, as opposed to a loss of elementary functions, and is consistent with World Health Organization definitions of impairment, disability, and handicap. There is no doubt that ADL outcomes are required in therapeutic drug studies on vascular dementia, and there is a good rationale and some evidence for the use of ADL scales developed for therapeutic research in Alzheimer disease, favoring scales devoid of items sensitive to physical disabilities. Similarly, ADL-related clinical milestones could be used for longer-term studies aiming predominantly at slowing progression of disease in both early and later stages of dementia. Slower decline in ADL and delay in reaching ADL-related clinical milestones should be considered as valid outcomes by regulatory bodies in the process of dementia drug approval.