The prevalence of dementia in a general practice sample: Upward revision of reported rate after follow‐up and reassessment

A subsample (N=204) of a consecutive series of 378 general practice patients aged 70+, previously given the Mental Function Test (MFT) and reported to show a prevalence of dementia of 0.8% (Jachuck et al., 1986), was followed and survivors retested three years later. Dementia was categorized as definite, probable, possible or absent, based on AGECAT and on clinical diagnoses using ICD -10 criteria. The diagnoses were checked against patients' scores on the CAMCOG, MMSE, AMT, CAPE and Blessed Dementia Scale, and test-retest differences on the MFT were noted. Patients who could not be interviewed were reassessed from their first MFT scores and the practice's research records. The MFT's performance and ability to predict death or dementia were examined. The prevalence of definite/probable dementia in the original sample is retrospectively reevaluated as about 11%. The rate in the general population aged 70+ is tentatively estimated after age adjustment to be approximately 9%, similar to that reported earlier (Kay et al., 1970). The age-specific rates approximate to those derived from analysis of published data (Jorm et al., 1987). It is concluded that the original estimate was too low. The prevalence of dementia among the Newcastle elderly does not appear to have fallen.