Incidence of dementia: preliminary findings from the Nottingham Longitudinal Study of Activity and Ageing.
In a 4-year follow-up of 1,042 randomly sampled elderly people (aged 65+), levels of dementia were assessed using a two-phase case finding procedure (screening followed by clinical interview) among survivors. Clinical information on those not re-interviewed was provided by death certificates, hospital case notes or postal questionnaires. The unweighted 4-year cumulative incidence of dementia was 4.3%, with age-specific rates of 0.9, 2.8, 5.2, 9.0 and 8.7% for the age groups 65-69, 70-74, 75-79, 80-84, and 85-89, respectively.