DeCarli C, Murphy D G, Tranh M, Grady C L, Haxby J V, Gillette J A, Salerno J A, Gonzales-Aviles A, Horwitz B, Rapoport S I
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
Neurology. 1995 Nov;45(11):2077-84. doi: 10.1212/wnl.45.11.2077.
To assess the association of MRI white matter hyperintensities (WMHI) with cognitive performance, cerebral structure, and cerebral metabolism in 51 healthy individuals aged 19 to 91 years without cerebrovascular risk factors.
Abnormal white matter signals have been associated with brain atrophy, reduced cerebral blood flow, focal neurologic signs, gait disorder, and poorer neuropsychological test performance. Most studies of WMHI, however, include subjects with hypertension or other identifiable causes of cerebrovascular disease that may have an independent effect on brain structure and function. To assess brain changes associated with WMHI independent of cerebrovascular risk factors, we determined WMHI volume, brain volume, cerebral metabolism, and cognitive performance for a group of subjects free of medical illness. Regional cerebral metabolism and cognitive domains were also assessed to evaluate the possible role of frontal lobe dysfunction in subjects with WMHI.
Cross-sectional study of 51 very healthy subjects aged 19 to 91 years.
WMHI, brain, and CSF volumes were determined by MRI segmentation. Neuropsychological tests were employed to assess multiple cognitive domains. Brain metabolism was determined from 18-fluoro-2-deoxy-D-glucose PET. Multivariate relations were tested with stepwise linear regression. Models included the potential confounders of age and education where appropriate.
The distribution of WMHI volume was bimodal, with five subjects having WMHI volumes beyond three SDs from the normally distributed population. A WMHI volume of greater than 0.5% of intracranial volume was considered abnormal. Within the multivariate models, WMHI volumes were significantly predictive of increased ventricular volume, reduced brain volume, and reduced cognitive scores. Subjects with greater than 0.5% WMHI volume also had significantly lower frontal lobe metabolism, significantly higher systolic blood pressure, significantly larger ventricular volume, and significantly lower scores on frontal lobe-mediated neuropsychological tests than age-matched controls.
WMHI volume is associated with structural and functional brain changes even within a group of very healthy individuals. WMHI is associated with poorer frontal lobe cognitive function and, when severe, is accompanied by significantly reduced frontal lobe metabolism. Subjects with large WMHI volumes have significantly higher systolic blood pressure, brain atrophy, reduced cerebral metabolism, and lower scores on tests of frontal lobe function than age-matched controls. Large amounts of WMHI are, therefore, pathologic and may be related to elevated systolic blood pressure even when it is within the normal age-related range.
评估51名年龄在19至91岁之间、无脑血管危险因素的健康个体中，磁共振成像（MRI）白质高信号（WMHI）与认知表现、脑结构和脑代谢之间的关联。
白质信号异常与脑萎缩、脑血流量减少、局灶性神经体征、步态障碍以及较差的神经心理学测试表现相关。然而，大多数关于WMHI的研究纳入了患有高血压或其他可识别脑血管疾病病因的受试者，这些因素可能对脑结构和功能有独立影响。为了评估与WMHI相关的脑变化，而不考虑脑血管危险因素，我们测定了一组无疾病受试者的WMHI体积、脑体积、脑代谢和认知表现。还评估了局部脑代谢和认知领域，以评估额叶功能障碍在WMHI受试者中的可能作用。
对51名年龄在19至91岁之间的非常健康的受试者进行横断面研究。
通过MRI分割确定WMHI、脑和脑脊液体积。采用神经心理学测试评估多个认知领域。通过18氟-2-脱氧-D-葡萄糖正电子发射断层扫描（PET）测定脑代谢。用逐步线性回归检验多变量关系。模型在适当情况下纳入了年龄和教育程度等潜在混杂因素。
WMHI体积分布呈双峰，有5名受试者的WMHI体积超出正态分布人群三个标准差以上。WMHI体积大于颅内体积的0.5%被认为异常。在多变量模型中，WMHI体积可显著预测心室体积增加、脑体积减小和认知得分降低。WMHI体积大于0.5%的受试者与年龄匹配的对照组相比，额叶代谢也显著降低，收缩压显著升高，心室体积显著增大，额叶介导的神经心理学测试得分显著降低。
即使在一组非常健康的个体中，WMHI体积也与脑结构和功能变化相关。WMHI与较差的额叶认知功能相关，严重时伴有额叶代谢显著降低。WMHI体积大的受试者与年龄匹配的对照组相比，收缩压显著更高，有脑萎缩、脑代谢降低以及额叶功能测试得分更低的情况。因此，大量的WMHI是病理性的，即使收缩压在正常年龄相关范围内，也可能与收缩压升高有关。
