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.

The paraphrenias raise a number of problems common to many other disorders in the field of psychiatry, and their solution might therefore advance knowledge in a number of directions. The relationship between paraphrenic, paranoid and schizophrenic illness has long been disputed, and no view at present commands general acceptance. It has seemed to us that these controversies have often turned upon unacknowledged assumptions as to whether clinical, prognostic or genetic criteria, or all of these, were to be employed to decide the issue.

SynopsisA survey was made of 274 non-institutionalized persons aged 70 and over living in Hobart. The prevalence of dementia and of depression was measured by interviewing subjects using a modified version of the Geriatric Mental State Schedule (GMS) (Copeland et al. 1976) and the Mini Mental State Examination (MMSE) (Folstein et al. 1975). Rates of morbidity were derived from different diagnostic procedures. These were: (1) diagnoses made by a psychiatrist (A.S.H.) directly from the interview schedules and audiotapes, and rated as mild, moderate or severe; (2) the criteria laid down in DSM-III, converted into algorithms describing 3 degrees of severity; and (3) the algorithms for pervasive dementia and depression proposed by Gurland et al. (1983), and from these authors' rational scales. In addition, the relation between scales for dementia and for depression and the diagnosed categories was examined. Some problems in applying these methods to aged persons in the community are discussed. It is concluded that more detailed specification of criteria is desirable if the comparative epidemiology of dementia and depression in old age is to advance.

Community surveys abroad have shown that there is a high prevalence of serious mental illness in old age, much of which is not treated in hospital (Gruenberg, 1961; Nielsen, 1963). Most community surveys of the aged in this country have, however, been concerned chiefly with general medical and social problems (Sheldon, 1948; Simonds and Stewart, 1954), or have formed part of whole-population studies and recorded only the most severe kinds of mental disturbance in old age (Mayer-Gross, 1948). An exception is the study of a Scottish rural practice by Primrose (1962).