Alexander G E, Furey M L, Grady C L, Pietrini P, Brady D R, Mentis M J, Schapiro M B
Laboratory of Neurosciences, National Institute on Aging, Bethesda, MD 20892, USA.
Am J Psychiatry. 1997 Feb;154(2):165-72. doi: 10.1176/ajp.154.2.165.
Clinical heterogeneity in Alzheimer's disease has been widely observed. One factor that may influence the expression of dementia in Alzheimer's disease is premorbid intellectual ability. It has been hypothesized that premorbid ability, as measured by educational experience, reflects a cognitive reserve that can affect the clinical expression of Alzheimer's disease. The authors investigated the relation between estimates of premorbid intellectual function and cerebral glucose metabolism in patients with Alzheimer's disease to test the effect of differing levels of premorbid ability on neurophysiological dysfunction.
In a resting state with eyes closed and ears occluded, 46 patients with Alzheimer's disease were evaluated with positron emission tomography and [18F]-2-fluoro-2-deoxy-D-glucose to determine cerebral metabolism. Premorbid intellectual ability was assessed by a demographics-based IQ estimate and performance on a measure of word-reading ability.
After the authors controlled for demographic characteristics and dementia severity, both estimates of premorbid intellectual ability were inversely correlated with cerebral metabolism in the prefrontal, pre-motor, and left superior parietal association regions. In addition, the performance-based estimate (i.e., reading ability) was inversely correlated with metabolism in the anterior cingulate, paracentral, right orbitofrontal, and left thalamic regions, after demographic and clinical variables were controlled for.
The results suggest that higher levels of premorbid ability are associated with greater pathophysiological effects of Alzheimer's disease among patients of similar dementia severity levels. These findings provide support for a cognitive reserve that can alter the clinical expression of dementia and influence the neurophysiological heterogeneity observed in Alzheimer's disease.
阿尔茨海默病的临床异质性已被广泛观察到。一个可能影响阿尔茨海默病痴呆表现的因素是病前智力水平。据推测，通过教育经历衡量的病前能力反映了一种认知储备，它可以影响阿尔茨海默病的临床表型。作者研究了阿尔茨海默病患者病前智力功能评估与脑葡萄糖代谢之间的关系，以测试不同水平的病前能力对神经生理功能障碍的影响。
在闭眼堵耳的静息状态下，对46例阿尔茨海默病患者进行正电子发射断层扫描和[18F]-2-氟-2-脱氧-D-葡萄糖检查以确定脑代谢。通过基于人口统计学的智商估计和单词阅读能力测试来评估病前智力水平。
在控制了人口统计学特征和痴呆严重程度后，病前智力水平的两种评估均与前额叶、运动前区和左侧顶上联合区的脑代谢呈负相关。此外，在控制了人口统计学和临床变量后，基于表现的评估（即阅读能力）与前扣带回、中央旁小叶、右侧眶额叶和左侧丘脑区域的代谢呈负相关。
结果表明，在痴呆严重程度相似的患者中，较高水平的病前能力与阿尔茨海默病更大的病理生理效应相关。这些发现为认知储备提供了支持，认知储备可以改变痴呆的临床表型，并影响在阿尔茨海默病中观察到的神经生理异质性。
