ABSTRACT BACKGROUND: Praxis impairment may be one of the first symptoms manifested in dementia, primarily in cortical dementia. The Cambridge Cognitive Examination (CAMCOG) evaluates praxis, but little is known about the accuracy of CAMCOG for diagnosing dementia. The aims here were to investigate the accuracy of praxis and its subitems in CAMCOG (constructive, ideomotor and ideational subitems) for diagnosing Alzheimer’s disease (AD) among elderly patients. DESIGN AND SETTING: Cross-sectional study on community-dwelling elderly people. METHODS: 158 elderly patients were evaluated. CAMCOG, Mini-Mental State Examination and Pfeffer Functional Activities Questionnaire were used. ROC curve analysis was used to establish cutoff points. RESULTS: The total scores for praxis and the constructive subitem presented significant differences (P < 0.0001) between healthy elderly people and AD patients. Stage of dementia (clinical dementia rating, CDR = 0, 1 and 2) showed that total and constructive praxis can be used to classify the stages of dementia (mild and moderate cases), i.e. constructive praxis classified 88% of the patients with mild dementia (P < 0.0001) while total praxis classified 56% with moderate dementia. Comparison of normal controls (NC) and mild dementia cases showed specificity of 71% and sensitivity of 88% (AUC = 0.88; P < 0.0001). CONCLUSION: Some praxis subtests can have higher predictive diagnostic value for detecting Alzheimer’s disease in mild stages (total praxis AUC = 0.858; P < 0.0001; constructive AUC = 0.972; P < 0.0001). Constructive praxis as measured using CAMCOG may contribute towards diagnosing dementia, because occurrence of impairment of praxis may help in recognizing an evolving dementia syndrome.

RESUMO O teste do desenho do pentágono (PDT) é um teste de rastreio cognitivo simples. Objetivo: O objetivo deste estudo foi avaliar o desempenho de uma escala específica de pontuação da PDT em idosos com doença de Alzheimer (DA) e controles saudáveis. Métodos: Estudo transversal, com 390 idosos, com mais de 60 anos de idade, com pelo menos dois anos de escolaridade. Todos os participantes passaram por anamnese clínica e neuropsicológica, incluindo o Cambridge Cognitive Examination (CAMCOG), o Mini-Exame do Estado Mental (MEEM) e o Teste do Desenho do Relógio (TDR). A avaliação do PDT com a escala Bourke et al. foi feita de forma cega. Resultados: As análises PDT do escore binário do MEEM (0 e 1 ponto) não discriminaram DA dos controles (p = 0,839). Contudo, quando PDT foi avaliada pela escala Bourke et al., verificou-se diferenças estatisticamente significativa (p <0,001). A PDT não sofreu interferência da escolaridade, apresentando sensibilidade de 85,5% e especificidade de 66,9% para discriminar os diferentes estágios clínicos da demência. A escala também mostrou correlação com os testes cognitivos aplicados (p <0,001). Uma diferença de um ponto na escala Bourke et al. foi associada com OR (odds ratio) de 3,46 para DA. Conclusão: PDT pode ser utilizada como rastreio cognitivo para casos suspeitos de demência, especialmente DA, independentemente.

ABSTRACT The Pentagon Drawing Test (PDT) is a common cognitive screening test. Objective: The aim of this study was to evaluate performance properties of a specific PDT scoring scale in older adults with Alzheimer's disease (AD) and healthy controls. Methods: A cross-sectional study of 390 elderly patients, aged 60 years or older with at least two years of education was conducted. All participants completed clinical and neuropsychological evaluations, including the Cambridge Cognitive Examination, the Mini-Mental State Examination (MMSE), and the Clock Drawing Test. All PDT were blindly scored with the scale of Bourke et al. Results: PDT analyses of the binary score on the MMSE (0 or 1 point) did not discriminate AD from controls (p = 0.839). However, when PDT was analyzed using the Bourke et al. scale, the two groups could be distinguished (p <0.001). PDT was not affected by education, showed sensitivity of 85.5% and specificity of 66.9%, discriminated different clinical stages of dementia, and correlated with the other cognitive tests (p <0.001). A 1-point difference on the Bourke et al. scale was associated with an odds ratio of 3.46 for AD. Conclusion: PDT can be used as a cognitive screen for suspected cases of dementia, especially AD, irrespective of educational level.