Neural correlates of mild cognitive impairment

描述（由申请人提供）：本研究的目的是研究轻度认知障碍（MCI）的不同病因和认知特征，轻度认知障碍（MCI）是一种临床特征，最初被定义为识别处于阿尔茨海默病（AD）临床前阶段的个体。现在很清楚，很大一部分患有轻度认知障碍的个体不会发展为AD，因此了解轻度认知障碍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的两种可能的病因，这可能导致MCI的不同认知特征。在某些情况下，用于对轻度认知障碍进行分类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，白质信号高强度（WMH）与工作记忆缺陷有关，这是脑血管疾病的一种迹象。因此，我们预测患有MCI和高WMH的个体将有工作记忆缺陷，从而导致情景记忆缺陷。利用海马萎缩作为海马功能障碍的标志，我们预测患有MCI和海马萎缩的个体将在正常工作记忆中表现出典型的情景记忆缺陷。我们还将通过fMRI来比较工作记忆和情景记忆任务时大脑活动的模式，来研究这些MCI个体记忆损伤的机制。我们预测，患有WMH的MCI个体在执行工作记忆任务时，其背外侧前额叶皮层（一个已知与工作记忆有关的区域）的激活程度会降低。相反，我们预测患有海马萎缩的MCI个体在执行情景记忆任务时海马激活会减少。

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.