THE EPIDEMIOLOGY OF ALZHEIMER'S DISEASE

Epidemiological research on Alzheimer's disease offers four contributions: the possibility of identifying risk factors; completion of the clinical picture; information for services and policy-making; and the construction of instruments for screening and for measuring change over time. Prevalence surveys have often not attempted to differentiate the types of dementia. The incidence rate is believed to be about 1% in the elderly as a whole, but it rises steeply with age. Risk factors reported so far are age, a family history of Alzheimer-type dementia, having Down's syndrome or a family history of it, head injury and thyroid disease. For further progress, particularly in identifying risk factors, the need now is to have uniform criteria for the presumptive diagnosis of Alzheimer's disease; and for a number of well-designed case-control studies on sizeable samples.