INFLUENCE OF AGGREGATION OF VASCULAR RISK FACTORS ON NEUROPSYCHOLOGICAL PERFORMANCE AND WHITE MATTER LESIONS IN EARLY ALZHEIMER’S DISEASE
L.B.G.Tay, M.S. Chong, P.C.M. Chan, Y.Y. Sitoh, W.S. Lim
J Aging Res Clin Practice 2012;1(2):109-114
Objective: To determine the influence of aggregation of vascular risk factors independent of cerebral infarcts on neuropsychological test performance in individuals with early Alzheimer’s disease (AD), and the mechanisms underlying this association. Methods: This is a cross-sectional study of 67 AD and 32 vascular dementia (VaD) subjects of mild severity, excluding Alzheimer’s disease subjects with a past history of stroke or transient ischemic attack, or who had radiological evidence of infarcts. Subjects with Alzheimer’s disease were stratified into 2 groups based on the number of vascular risk factors: i) AD-RF- (n=45) with 0-2 risk factors, and ii) AD-RF+ (n=22) with 3-5 risk factors. All subjects had undergone neuroimaging, and white matter lesions were graded using the age-related white matter changes (ARWMC) rating scale. We compared the neuropsychological test performance between AD-RF-, AD-RF+ and VaD groups, adjusting for the influence of white matter lesions. Results: AD-RF+ subjects displayed a trend towards greater impairment in amnestic domains relative to AD-RF- and VaD. In addition, AD-RF+ subjects were significantly more impaired than AD-RF- in the non-amnestic domains, being intermediate to VaD in category fluency (p=0.05) and block design (p=0.03), and more impaired than VaD in confrontational naming (p=0.05). There was incremental white matter lesion burden across AD-RF-, AD-RF+ and VaD (p<0.01), with a significant effect on non-amnestic domains. Conclusions: This study has shown that an aggregation of vascular risk factors aggravates impairment in both amnestic and non-amnestic domains in early Alzheimer’s disease, independent of the presence of cerebral infarcts. White matter lesions, especially those in the frontal regions, represent one mechanism underlying this relation.