OBJECTIVES: To assess the distribution of dementia subtypes in Brazil using a population-based clinicopathological study. METHOD: Brains from deceased individuals aged ≥50 years old were collected after the next of kin signed an informed consent form and provided information through standardized questionnaires. Post-mortem clinical diagnoses were established in consensus meetings, and only cases with moderate or severe dementia or without cognitive impairment were included in the analysis. Immunohistochemical neuropathological examinations were performed following the universally accepted guidelines. A diagnosis of Alzheimer's disease was made when there were at least both a moderate density of neuritic plaques (Consortium to Establish a Register for Alzheimer's disease B or C) and Braak stage III for neurofibrillary tangle distribution. For the diagnosis of vascular dementia, at least three zones or strategic areas had to be affected by infarcts, lacunae, or microinfarcts. RESULTS: From 1,291 subjects, 113 cases were classified as having moderate or severe dementia, and 972 cases were free of cognitive impairment. The neuropathological diagnoses of the dementia sub-group were Alzheimer's disease (35.4%), vascular dementia (21.2%), Alzheimer's disease plus vascular dementia (13.3%), and other causes of dementia (30.1%). Small-vessel disease, which alone was not considered sufficient for a vascular dementia diagnosis, was present in 38.9% of all of the dementia cases and in 16.8% of the group without cognitive impairment (odds ratio = 2.91; 95% confidence interval, 1.53-5.51), adjusted for age, sex, and education. CONCLUSIONS: The relatively high frequencies of vascular dementia and small-vessel disease in the dementia sub-group constitute relevant findings for public health initiatives because control of vascular risk factors could decrease the prevalence of dementia in developing countries.

Resumo Os modelos de estadiamento neuropatológico da doença de Alzheimer (DA) têm sido desenvolvidos nos últimos 20 anos. Entretanto, têm sido quase exclusivamente testados em caucasianos de ascendência norte-européia ou em asiáticos. Objetivos: verificar quais dos critérios neuropatológicos discrimina melhor entre a DA e o envelhecimento normal em uma casuística clinicopatológica brasileira bem caracterizada. Métodos: uma amostra aleatória de 89 casos do Banco Brasileiro de Encéfalos do Estudo de Envelhecimento Cerebral foi submetida à avaliação neuropatológica completa com imunohistoquímica. As condições clínicas e funcionais foram avaliadas mediante entrevista com informante confiável. Os escores na Clinical Dementia Rating Scale (CDR) foram comparados com os escores dos estágios de Braak e Braak, do CERAD (Consortium to Establish a Registry for Alzheimer's Disease) e do consórcio NIA-Reagan (National Institute of Aging-Reagan Institute). Casos com diagnósticos neuropatológicos diferentes de DA foram excluídos (n=27). Resultados: Os 62 casos foram classificados em: CDR0=39, CDR0,5=9, CDR³1=14. Não havia diferenças quanto a idade, gênero e escolaridade entre os grupos. Os escores no CERAD correlacionaram-se melhor com os do CDR (r=0,5303; p<0,001). Os escores nos estágios de Braak e Braak foram significativamente mais elevados nos casos com CDR mais altos. A correlação do CDR com os escores dos critérios NIA-Reagan foi parcialmente rompida porque grande proporção de casos não se enquadrava em nenhuma das categorias diagnósticas destes critérios. Conclusões: Nesta casuística, os critérios do CERAD correlacionam-se melhor com os do CDR. Como observado por outros estudos, alguns casos de indivíduos cognitivamente normais, preencheram critérios neuropatológicos para o diagnóstico de DA.

Abstract The current neuropathological staging models of Alzheimer's disease (AD) have been developed within the last 20 years. Nevertheless, they were mostly tested on Caucasians of Northern European ancestry or on Asians. Objective: To verify which of the accepted neuropathologic criteria best discriminates AD from normal aging in a well characterized Brazilian clinicopathological series. Methods: A random sample consisting of 89 subjects belonging to the Brazilian Brain Bank of the Aging Brain Study were clinically and neuropathologically fully assessed using immunohistochemistry. Clinical and functional statuses were assessed by interviewing a reliable informant. The Clinical dementia rating scale (CDR) was compared to Braak and Braak stage, the consortium to establish a registry for Alzheimer's disease (CERAD) score and NIA-Reagan (National Institute of Aging - Reagan Institute) score. Subjects with a neuropathologic diagnosis other then AD were excluded (n=27). Results: The CDR score distribution for the 62 selected subjects was as follows: CDR0=39, CDR0.5=9, CDR³1=14. There were no differences regarding age, gender and education among the groups. CDR score correlated best with the CERAD score (r=0.5303; p<0.001) . Braak and Braak stage was significantly higher in subjects with higher CDR. Correlation of the NIA-Reagan criteria was partially disrupted because a large proportion of subjects did not fit any of its categories. Conclusions: In this series, CERAD criteria better correlated with the CDR groups. Consistent with earlier studies, some cognitively normal subjects have AD neuropathological diagnosis.