ABSTRACT
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 < 0.01). 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.
Subject(s)
Alzheimer Disease/diagnosis , Cognition Disorders/diagnosis , Cognition , Dementia/diagnosis , Mental Status Schedule , Adult , Aged , Aged, 80 and over , Brazil , Female , Humans , Male , Middle Aged , Psychometrics/methods , Reproducibility of ResultsABSTRACT
Several MRI studies have reported reductions in temporal lobe volumes in Alzheimer's disease (AD). Measures have been usually obtained with regions-of-interest (ROI) drawn manually on selected medial and lateral portions of the temporal lobes, with variable choices of anatomical borders across different studies. We used the fully automated voxel-based morphometry (VBM) approach to investigate gray matter abnormalities over the entire extension of the temporal lobe in 14 AD patients (MMSE 14-25) and 14 healthy controls. Foci of significantly reduced gray matter volume in AD patients were detected in both medial and lateral temporal regions, most significantly in the right and left posterior parahippocampal gyri and the left posterior inferior temporal gyrus/fusiform gyrus (P<0.05, corrected for multiple comparisons). At a more flexible statistical threshold (P<0.001, uncorrected for multiple comparisons), circumscribed foci of significant gray matter reduction were also detected in the right amygdala/enthorinal cortex, the anterior and posterior borders of the superior temporal gyrus bilaterally, and the anterior portion of the left middle temporal gyrus. These VBM results confirm previous findings of temporal lobe atrophic changes in AD, and suggest that these abnormalities may be confined to specific sites within that lobe, rather than showing a widespread distribution.
Subject(s)
Alzheimer Disease/pathology , Magnetic Resonance Imaging , Temporal Lobe/pathology , Aged , Aging/pathology , Atrophy , Female , Humans , Male , Middle AgedABSTRACT
Introduçäo: Estudos que utilizam as técnicas de PET, SPECT e ressonância magnética funcional têm permitido o mapeamento dos circuitos cerebrais ativados durante diversas tarefas cognitivas. O campo da memória declarativa tem sido um dos mais intensamente estudados. No presente estudo, usa-se a técnica de mapeamento do fluxo sanguíneo cerebral regional (FSCr) por SPECT para investigar mudanças na atividade cerebral durante uma tarefa de memória episódica, em voluntários idosos sadios (n=15). Métodos: Duas avaliações de SPECT foram realizadas na mesma sessäo, usando a técnica de dose dividida do traçador 99 m-Tc-HMPAO. Medidas de FSCr foram registradas durante uma tarefa de reconhecimento de material verbal previamente aprendido e durante uma tarefa-controle mais simples. Comparações de FSCr foram realizadas automaticamente, utilizando o programa Statistical Parametric Mapping (SPM). Resultados: Observou-se o aumento de FSCr durante a tarefa de memória em várias regiões cerebrais, incluindo: córtex pré-frontal lateral bilateralmente (mais acentuadamente à esquerda); porções posteriores e mediais de córtex parieto-occipital à esquerda; hemisférios cerebelares bilateralmente; e córtex temporal lateral bilateralmente (p<0,001, näo corrigido para comparações múltiplas). Foram observados também focos inesperados de diminuiçäo de FSCr em cíngulo posterior direito, córtex orbitofrontal esquerdo, córtex temporal inferior direito e vérmis cerebelar esquerdo (p>0,05, corrigido para comparações múltiplas). Conclusäo: Esses resultados sugerem que circuitos neuronais multifocais säo engajados durante memória de reconhecimento e replicam localizações cerebrais descritas anteriormente na literatura. O uso desse protocolo em pacientes com transtornos neuropsiquiátricos poderá permitir a investigaçäo de anormalidades cerebrais subjacentes aos déficits de memória presentes nesses transtornos
