A study of mild dementia in the community using a wide range of diagnostic criteria.

The result of, and difficulties in, applying a range of existing criteria for mild dementia to a random sample of community elderly aged 70 years and over is examined. By one or more criteria, 25% had mild dementia, and almost 30% of these had additional psychiatric disorders, mostly depression. Prevalence rates for mild dementia varied widely according to the different criteria. Rates of mild dementia increased with age. Poor specification of diagnostic criteria was a major problem. These criteria should be standardised and detailed, and prospective longitudinal studies conducted to elicit the natural history of this condition.