Psychometric properties of Cognitive Instruments in Vascular Dementia and Alzheimer's disease: a neuro-psychological study

OBJECTIVES: To describe elderly performance in the Bender Gestalt Test (BGT) and to discriminate its score by using types of errors as comparison among healthy controls, Alzheimer's disease (AD) patients, and vascular dementia (VD) patients. METHODS: We performed a cross-sectional analysis of 285 elderly individuals of both sexes, all over 60 years old and with more than 1 year of schooling. All participants were assessed through a detailed clinical history, laboratorial tests, neuroimaging, and neuropsychological tests including the BGT, the Cambridge Cognitive Examination (CAMCOG), the Mini-Mental State Examination (MMSE), the Geriatric Depression Scale (GDS), and the Pfeffer Functional Activities Questionnaire (PFAQ). The BGT scores were not used to establish diagnosis. RESULTS: Mean BGT scores were 3.2 for healthy controls, 7.21 for AD, and 8.04 for VD with statistically significant differences observed between groups (p < 0.0001). Logistic regression analysis was used to identify the main risk factors for the diagnostic groups. BGT's scores significantly differentiated the healthy elderly from those with AD (p <0.0001) and VD (p < 0.0001), with a higher area under the curve, respectively 0.958 and 0.982. BGT's scores also showed that the AD group presented 12 types of errors. Types of errors evidenced in the execution of this test may be fundamental in clinical practice because it can offer differential diagnoses between senescence and senility. CONCLUSION: A cut-off point of 4 in the BGT indicated cognitive impairment. BGT thus provides satisfactory and useful psychometric data to investigate elderly individuals.