To obtain age- and gender-specific estimates of the prevalence of dementia in Europe and to study differences in prevalence across countries, we pooled and re-analysed original data of prevalence studies of dementia carried out in some European countries between 1980 and 1990. The study followed these steps: census of existing datasets, collection of data in a standardized format, selection of datasets suitable for comparison, comparison of age and gender patterns. From the 23 datasets of European surveys considered, 12 were selected for comparison. Only population-based studies in which dementia was defined by DSM-III or equivalent criteria and in which all subjects were examined personally were included. Studies in which institutionalized subjects were not investigated were excluded. Age- and gender-specific prevalences were compared within and across studies and overall prevalences were computed. Although prevalence estimates differed across studies, the general age- and gender-distribution was similar for all studies. The overall European prevalences for the five-year age groups from 60 to 94 years, were 1.0, 1.4, 4.1, 5.7, 13.0, 21.6 and 32.2%, respectively. In subjects under 75 years the prevalence of dementia was slightly higher in men than in women; in those aged 75 years or over the prevalence was higher in women. The prevalence figures nearly doubled with every five years of increase in age.

We reanalyzed and compared current prevalence estimates of Alzheimer's disease in Europe. Studies characterized as follows qualified for comparison: dementia defined by the Diagnostic and Statistical Manual for Mental Disorders, 3rd edition, or equivalent criteria; Alzheimer's disease diagnosed by the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association or equivalent criteria; case-finding through direct individual examination; appropriate sample size; and inclusion of institutionalized persons. Of the 23 European surveys of dementia considered, six fulfilled the inclusion criteria. When age and sex were considered, there were no major geographic differences in the prevalence of Alzheimer's disease across Europe. Overall European prevalence (per 100 population) for the age groups 30 to 59, 60 to 69, 70 to 79, and 80 to 89 years was, respectively, 0.02, 0.3, 3.2, and 10.8. Prevalence increased exponentially with advancing age and, in some populations, was consistently higher in women. Prevalence remained stable over 15 years in one study.

SynopsisThe Lundby cohort consists of all inhabitants in a delimited area in Sweden studied in 1947 by Essen-Möller, then by Hagnell in 1957, and by Hagnell & Öjesjöin 1975. It has been claimed that depressive disorders have increased during the sixties and seventies. In order to examine this hypothesis on a normal population (the Lundby Study), comparisons were made of the incidence figures for depression during the periods 1947–57 and 1957–72, and during the five 5-year intervals within the period.

We selected, reanalyzed, and compared data from current prevalence studies of vascular dementia in Europe. Inclusion criteria were: dementia defined by the Diagnostic and Statistical Manual for Mental Disorders, edition 3, or equivalent criteria; case finding through direct individual examination; appropriate sample size; and inclusion of institutionalized persons. Mixed dementia was combined with vascular dementia. Of the 23 surveys of dementia considered, five fulfilled the inclusion criteria. Age-specific prevalence varied more widely for men than for women; differences were greater in older ages. The prevalence increased steeply with advancing age in all countries, and was generally higher in men; it declined over 15 years in the age class of 80 to 89 years in one Swedish population. Within populations, Alzheimer's disease was generally more common than vascular dementia. Unfortunately, prevalence studies of vascular dementia are limited in Europe and worldwide, and their comparison is impeded by the lack of common diagnostic criteria.

The present study is based on the so-called 1957 Lundby cohort, a geographically defined normal Swedish population of 2612 individuals who were evaluated for mental disorders in 1957 and 1972. The annual age-standardised first incidence of depression, with or without other psychiatric symptoms, all degrees of impairment included, was found to be 4.3 per 1000 person years in men and 7.6 per 1000 person years in women. Up until 70 years of age, the cumulative probability of suffering a first episode of depression was 27% in men and 45% in women.