Neural correlates of mild cognitive impairment

描述（由申请人提供）：本研究的目的是检查轻度认知障碍（MCI）的不同病因和认知特征，MCI是最初定义用于识别阿尔茨海默病（AD）临床前阶段个体的临床特征。现在很清楚，很大一部分MCI患者不会进展为AD，因此了解MCI成为老龄化人口的一个更普遍的问题。我们认为，海马功能障碍和血管疾病是MCI的两个可能的病因，可能导致不同的认知特征的MCI。在某些情况下，用于分类MCI的情景记忆缺陷可能是工作记忆缺陷的次要影响。有一些证据表明，白色信号高信号（WMH），脑血管疾病的迹象，与工作记忆的缺陷。因此，我们预测患有MCI和高WMH的个体将具有导致情景记忆缺陷的工作记忆缺陷。使用海马萎缩作为海马功能障碍的标志物，我们预测患有MCI和海马萎缩的个体将显示具有正常工作记忆的经典情景记忆缺陷。我们还将研究记忆障碍的机制，在这些群体的个人与MCI使用功能磁共振成像比较模式的大脑活动在工作记忆和情景记忆任务的性能。我们预测，MCI个人与WMH将显示减少激活的背外侧前额叶皮层，一个已知的区域参与工作记忆，在执行工作记忆任务。相比之下，我们预测MCI个体海马萎缩将显示减少海马激活过程中的情节记忆任务的性能。

DESCRIPTION (provided by applicant): The purpose of this study is to examine different etiologies and cognitive profiles of mild cognitive impairment (MCI), a clinical characterization originally defined to identify individuals in the preclinical phase of Alzheimer's Disease (AD). It is now clear that a large portion of individuals with MCI do not progress to AD, thus understanding MCI becomes a more general problem for the aging population. We propose that hippocampal dysfunction and vascular disease are two possible etiologies of MCI that may lead to different cognitive profiles of MCI. It is possible that the episodic memory deficit used to classify MCI is, in some cases, a secondary effect of deficits in working memory. There is some evidence that white matter signal hyperintensities (WMH), an indication of cerebrovascular disease, are correlated with deficits in working memory. Thus, we predict that individuals with MCI and high WMH will have deficits in working memory that lead to deficits in episodic memory Using hippocampal atrophy as a marker for hippocampal dysfunction, we predict that individuals with MCI and hippocampal atrophy will show classic episodic memory deficits with normal working memory. We will also examine the mechanisms of memory impairments in these groups of individuals with MCI by using fMRI to compare patterns of brain activity during performance on working memory and episodic memory tasks. We predict that MCI individuals with WMH will show reduced activation in the dorsolateral prefrontal cortex, an area known to be involved in working memory, during performance on a working memory task. In contrast, we predict MCI individuals with hippocampal atrophy will show reduced hippocampal activation during performance on an episodic memory task.