Neuropsychological differentiation of Alzheimer's disease from vascular dementia

Abstract

SUMMARYThe purpose of this study was to determine whether cognitive test performances alone could distinguish patients with probable Alzheimer's disease from those with probable vascular dementia. Sixty-eight outpatients with clinical diagnoses of either Alzheimer's disease or vascular dementia were administered a brief battery of neuropsychological tests. Scores from the Boston Naming Test and the Hopkins Verbal Learning Test were identified as most discriminating of the groups. Seventy-seven per cent of the sample was correctly classified by a stepwise discriminant function analysis. Results of this study indicate that selected neuropsychological tests have moderate concurrent utility in the differential diagnosis of dementia.KEY woRDs-Alzheimer's disease, vascular dementia, neuropsychological tests, discriminant analysis.Alzheimer's disease (AD) is the cause of at least 50% of all cases of dementia in the elderly (Forster and Martin, 1990;Terry and Katzman, 1983). Its prevalence has been estimated at 10% of those over age 65 years (Evans et al., 1989). Jorm et al. (1987) determined that the prevalence of AD is 1.4% at age 65 years, with a doubling of this rate for every five years of age. Vascular dementia (VD) is the second most common cause of dementia in the elderly (Forster and Martin, 1990;Wisniewski and Terry, 1976) and can result from many different types of cerebrovascular disease (Funkenstein, 1988;Hachinski et al., 1975). Together, AD and VD are believed to account for at least 85% of all cases of dementia in postmortem studies (Bucht and Adolfsson, 1983;Wisniewski and Terry, 1976 are lacking, and no weight is given to the results of neuroimaging studies, which are often relied upon heavily in clinical decision-making (Funkenstein, 1988). Hachinski et al. (1975) also did not validate their clinical diagnoses (which were determined by Hachinski ischemia scores) against pathological evidence, although Rosen et al. (1 980) did so with a revised Hachinski score. Thus, discrimination of AD from multi-infarct dementia remains problematic, as does the differentiation of AD from cerebrovascular dementias generally. A valid and cost-effective way of discriminating VD from AD is still needed in order to more adequatelydiagnose, and hence manage, patients with dementia.Several studies have successfully distinguished demented patients (of varying etiologies) from healthy subjects with the use of neuropsychological tests alone (Eslinger et al., 1985;Storandt et al., 1984). Others have attempted to distinguish the cognitive profiles of AD patients from VD patients or those with other types of dementia (Hagberg and Gustafson, 1985;Olafsson et al., 1989;Parlato et al., 1990;Perez et al., 1975a Perez et al., , b, 1976Perez et al., , 1978 Tierney et ul., 1987). These studies have met with mixed success, due, in part, to great within-group variability. Specifically, the distribution of infarcts in VD patients is heterogeneous (Hagberg and Gustafson, 1985), as is the distribution of senile plaques and 08854230/92/0Y...

The Hopkins Verbal Learning Test and Screening for Dementia

“…A closer look at the other studies [2,5,9,11] revealed that our controls had a slightly lower performance than theirs. This may be explained by their very rigorous health screening of controls [2,5] or the lack of control for age, education, gender [2] and depression [2,11]. These factors may have overestimated the normal performance of elderly subjects in the previous studies.…”

“…A later study reported 96% sensitivity and 80% specificity for mild dementia (MMSE 118) [9]. In studies of its discriminative capacity for different types of dementia, the HVLT was found to have a moderate (64% [10] to 77% [11]) correct classification rate for AD and vascular dementia (VaD).…”

“…The HVLT has been found to have a particularly high sensitivity and specificity for Alzheimer's disease (AD), the most common form of dementia [2,10,11]. The original validation study of the HVLT [2] investigated 45 subjects with probable AD, 3 amnesiacs and 18 healthy subjects aged 65 and older.…”

“…In addition, potential confounds like age, gender, education [2] and depression [2,11] were not always adequately controlled for. These factors have been found to be risk factors for both AD and poor memory function and therefore studies not controlling for these factors may have overestimated the discriminative capacity of the HVLT.…”

Habilidades linguísticas de pacientes com demência vascular: estudo comparativo com a doença de Alzheimer

“…Ao contrário, relatos de melhor desempenho dos pacientes com DV na expressão linguística também são encontrados na literatura (Villardita, 1993;Powell et al, 1988;Barr et al, 1992;Chapman, 1997). Outros estudos ainda, não encontraram diferenças significativas entre o desempenho linguístico de pacientes com DV e pacientes com DA (Bentham et al, 1997;Vuorinen et al, 2000).…”