The Short Cognitive Performance Test (SKT): a preliminary study of its psychometric properties in Brazil

Background: Most instruments designed to detect dementia can lack appropriate sensitivity in the early stages of Alzheimer's disease (AD), and are subject to educational bias. The Short Cognitive Performance Test (Syndrom-Kurztest, SKT) is considered a suitable instrument to measure cognitive decline as it assesses memory, attention, and related cognitive functions, taking into account the speed of information processing. Objectives: The aim of this study was to examine the psychometric characteristics of the SKT as a dementia screening instrument in a Brazilian population sample, as compared to the Mini-mental State Examination (MMSE) and the Clock-Drawing Test (CDT). The effect of educational level on performance in the three screening tests was also verified. Methods: Fifty-one elderly subjects were assessed. Consensus diagnoses were established by an expert multidisciplinary team, considering clinical, neuropsychological and neuroimaging data. Subjects were further classified into those with (1) mild and moderate AD, (2) non-Alzheimer's dementia, (3) mild cognitive impairment, and (4) controls, according to National Institute for Communicative Disorders and Stroke - Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria. Results: Statistical analyses revealed high internal consistency for the SKT (Cronbach's alpha = 0. 80) and significant correlations between the total score and the SKT subscores separately (p < 0. 0 1). Comparison of the three tests revealed strong correlations between the SKT and the MMSE (r = -0.66, p < 0.0001) and between the SKT and the CDT (r = -0.57,p < 0.0001). The SKT, MMSE and CDT scores were correlated with education. Conclusions: The Brazilian version of the SKT maintains its original psychometric properties and displays significant correlation with previously validated screening tools for dementia. Like other dementia screening tests, the SKT is subject to educational bias.