Study objective. To test the following hypothesis, in the context of the relevance and public health implications of the epidemiology of dementia: the prevalence rates of both, dementia and Alzheimer's disease remain stable ten years after the first study in a representative sample of the elderly general population.

Design. Epidemiological First Study. (The Zaragoza Study): Two-phase screening (lay interviewers and psychiatrics) in a representative, census sample (n=1,080) of elderly community dwellers (65+). Second Study, 10 years later (The Zarademp Project, designed to be a two waves, cross-sectional and follow-up studies to document the incidence and risk-factors for dementia). Again, a two-phase screening (lay interviewers and psychiatrics) was done in the baseline, cross-sectional study on a representative sample of n=4,803 elderly in the general population.

Instruments. Spanish versions of the Mini-Mental Status Examination or Mini-Examen Cognoscitivo (MEC), Geriatric Mental State (GMS and AGCAT computer program), History and Aetiology Schedule (HAS), Lawton and Katz disability scales; Hachinski's scale, all incorporated into the ZARADEMP interview, Cut-off points according to efficiency coefficients documented in the baseline study. Diagnosis of dementia according to GMS-AGECAT and DSM criteria.

Results. The prevalence of dementia if the first, Zaragoza Study was 5.5p.cent (6.4p.cent in males and 4.8p.cent in females). The prevalence of Alzheimer's disease was 4.3p.cent (4.8p.cent in males and 3.9p.cent in females). In the cross-sectional study, 10 years later (Zarademp Project), the prevalence of dementia was 7.1p.cent (4.4p.cent in males and 8.9p.cent in females). The prevalence of Alzheimer's disease was 4.6p.cent (2.4p.cent in males and 6.2p.cent in females). While specific statistical coefficients were not calculated due to non-identical methodologies used, both the global prevalence and the distribution by age were similar in both investigations.

Conclusions. It is suggested that the prevalence rate of both, global dementia and Alzheimer's disease have remained stable in the last ten years in Zaragoza, a rather typical Spanish and South-European city.