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.

Our objectives were to investigate the utility of the Hachinski Ischemic Score (HIS) in differentiating patients with pathologically verified Alzheimer's disease (AD), multi-infarct dementia (MID), and "mixed" (AD plus cerebrovascular disease) dementia, and to identify the specific items of the HIS that best discriminate those dementia subtypes. Investigators from six sites participated in a meta-analysis by contributing original clinical data, HIS, and pathologic diagnoses on 312 patients with dementia (AD, 191; MID, 80; and mixed, 41). Sensitivity and specificity of the HIS were calculated based on varied cutoffs using receiver-operator characteristic curves. Logistic regression analyses were performed to compare each pair of diagnostic groups to obtain the odds ratio (OR) for each HIS item. The mean HIS (+/- SD) was 5.4 +/- 4.5 and differed significantly among the groups (AD, 3.1 +/- 2.5; MID, 10.5 +/- 4.1; mixed, 7.7 +/- 4.3). Receiver-operator characteristic curves showed that the best cutoff was < or = 4 for AD and > or = 7 for MID, as originally proposed, with a sensitivity of 89.0% and a specificity of 89.3%. For the comparison of MID versus mixed the sensitivity was 93.1% and the specificity was 17.2%, whereas for AD versus mixed the sensitivity was 83.8% and the specificity was 29.4%. HIS items distinguishing MID from AD were stepwise deterioration (OR, 6.06), fluctuating course (OR, 7.60), hypertension (OR, 4.30), history of stroke (OR, 4.30), and focal neurologic symptoms (OR, 4.40). Only stepwise deterioration (OR, 3.97) and emotional incontinence (OR, 3.39) distinguished MID from mixed, and only fluctuating course (OR, 0.20) and history of stroke (OR, 0.08) distinguished AD from mixed. Our findings suggest that the HIS performed well in the differentiation between AD and MID, the purpose for which it was originally designed, but that the clinical diagnosis of mixed dementia remains difficult. Further prospective studies of the HIS should include additional clinical and neuroimaging variables to permit objective refinement of the scale and improve its ability to identify patients with mixed dementia.

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.

The aim of the present study was to investigate cause-specific mortality in people with intellectual disability (ID). It was based on a 35-year follow-up study of a nation-wide population of 2369 subjects aged between 2 and 97 years. The 1095 deceased people had accumulated 64 539 person-years. The research took the form of a prospective cohort study with mortality follow-up. Observed and expected deaths were calculated as standardized mortality ratios using the Finnish general population as the reference. Cause-specific mortality ratios were calculated by the level of ID, sex and age. The three most common causes of death were cardiovascular diseases, respiratory diseases and neoplasms. Disease mortality was high up to 40 years of age, but did not increase thereafter. The difference between sexes in cause-specific mortality was smaller than in the general population. Cause-specific mortality differed significantly from the general population, with reduced mortality from neoplasms and external causes, but ageing individuals with mild ID had similar mortality patterns to the general population. The disparities in the cause-specific mortality between younger people with ID and the general population fade with advancing age, producing similar health risks. In preventative work, special attention should focus on common diseases and accidents in the community.

SUMMARY With neuropathological diagnosis as the point of reference, the accuracy of clinical diagnosis was studied in a series of 58 demented patients. Alzheimer's disease and multi-infarct dementia were recognised with sensitivities and specificities exceeding 70%, whereas combined dementia as a separate group was relatively unreliably diagnosed. The value of Hachinski's Ischaemic Score in differentiating between Alzheimer's disease and vascular dementias was demonstrated. Its performance was to some extent improved by assigning new weights to the items. In a logistic regression model, fluctuating course, nocturnal confusion, and focal neurological symptoms emerged as features with the best discriminating value, and helped to diagnose correctly 89% of the Alzheimer and 71% of the vascular dementia patients.The major form of dementia in old age is senile dementia of Alzheimer type (SDAT), the most common type of Alzheimer's disease (AD). The neuropathological picture is characterised by three microscopical changes: neurofibrillary tangles and neuritic plaques in the neo-and paleocortex, together with granulovacuolar degeneration in the hippocampus.' Multi-infarct dementia, the second most common cause of dementia, is due to multiple gross or microscopic infarcts, often widely spread throughout the brain tissue.2 In addition, many demented old people show a combination of changes, all of which may contribute to the dementing process. The most important combination is that of AD and ischaemic infarcts, or combined dementia.' A solid diagnostic differentiation of these conditions can only be made by a postmortem neuropathological examination. Brain biopsy can be used to identify the Alzheimer process during life, but this invasive procedure is not acceptable as a routine diagnostic method in senescence. Thus, the clinical identification of the major forms of senile dementia must be largely based on a careful analysis of clinical data.3It is therefore of interest to investigate the accuracy of clinical diagnosis using neuropathological diagnosis as the point of reference.4 6 retrospective study by Todorov et al4 comprised 776 patients studied during a period of ten years. In that study, the sensitivity of the clinical diagnosis was 28% for SDAT, 57% for multi-infarct dementia, and 30% for combined cases; the corresponding specificities were 43%, 39%, and 48%. Thus, the accuracy of clinical diagnosis proved poor. It would seem likely that better accuracy might be reached in a prospective study with uniform diagnostic criteria throughout the study period. We now report results of a prospective analysis of 58 demented patients. The systematic approach devised by Hachinski etal.' was evaluated as a method to differentiate between AD and vascular dementia.