The Intracranial Atherosclerotic Disease and Cognitive Impairment Study

描述(由申请人提供)：基本原理。在美国，每年约有80,000名患者患有颅内动脉硬化症(ICAD)，这是一种已知的中风原因。此外，它还被怀疑与认知障碍和痴呆症有关。然而，尽管这是一个如此常见的健康问题，但这种疾病的流行程度尚不清楚。此外，ICAD与认知障碍和痴呆症的关联程度仍未得到研究。我们计划研究ICAD在美国老年人群中的流行情况，并确定其与认知障碍和痴呆症的关系。目的：我们建议的项目的总体目标是在ARIC-NCS中对2000名正在接受MRI检查的受试者进行辅助研究。目的是1)评估70-89岁ARIC参与者中ICAD的患病率；2)确定ICAD是否与痴呆症或轻度认知损害有关。设计/方法：社区中的动脉粥样硬化风险是一个由美国国立卫生研究院资助的心血管队列，在过去的25年里跟踪了大约16,000名年龄在45岁-之间的受试者。现在，由NHLBI资助的ARIC神经认知研究(ARIC-NCS)将在2000年对其余7000名受试者进行磁共振成像(MRI)。神经认知测试将作为ARIC-NCS的一部分进行，选择的2000名磁共振受试者的样本将包括痴呆症患者(n=358)、轻度认知障碍(MCI)患者(n=761)和正常参与者(n=878)。我们计划获取这2000名受试者的磁共振血管成像(MRA)研究，同时为ARIC-NCS采集MRI图像。我们将使用MRA测量管腔狭窄，这是ICAS的标准临床参数。此外，我们将使用一种新的高分辨率磁共振序列来测量颅内血管壁厚。血管壁厚度可以检测到动脉粥样硬化的改变，而不会有任何明显的狭窄，并且可能是动脉粥样硬化性疾病负担的更好的衡量标准。此外，与管腔狭窄相比，管壁厚度与认知障碍或痴呆症的相关性也可能更强。我们将使用两种不同的ICAD定义来确定患病率：1.管腔狭窄50%，2.管壁厚度0.6 mm。这意味着什么。这项研究基于新的数据，表明无症状的ICAD与普通人群中老年人的认知障碍有关。此外，无症状的ICAD可能与认知障碍有关，在老年人群中，由于慢性灌流不足，MRI上没有脑梗塞，ICAD可能与认知障碍有关。这也将是第一次确定无症状ICAD在美国老年人群中的患病率及其对认知障碍的影响的研究。

DESCRIPTION (provided by applicant): Rationale. Intracranial atherosclerotic disease (ICAD) is a known cause of stroke in about 80,000 patients every year in US. In addition it is suspected to be associated with cognitive impairment and dementia. However, despite being such a common health problem, the prevalence of this disease is unclear. Also, the degree of association of ICAD with cognitive impairment and dementia remains unstudied. We plan to study the prevalence of ICAD in US elderly population and also determine its association with cognitive impairment and dementia. Aims: The broad objective of our proposed project is to conduct an ancillary study in the subsample of 2000 subjects who are undergoing MRI in ARIC-NCS. Aims are 1) to estimate the prevalence of ICAD in the ARIC participant aged 70-89 years and 2) to determine whether ICAD is associated with dementia or mild cognitive impairment. Design/Methods: Atherosclerosis Risk in Communities is an NHBLI funded cardiovascular cohort that has followed about 16,000 subjects, aged 45-64 for last 25 years. Now, ARIC Neurocognitive Study (ARIC-NCS), funded by NHLBI, will perform magnetic resonance imaging (MRI) in 2000 of the remaining 7000 subjects. Neurocognitive testing will be performed as part of ARIC-NCS and the sample of 2000 subjects selected for MRI will include subjects with dementia (n=358), mild cognitive impairment (MCI) (n=761), and normal participants (n=878). We plan to acquire magnetic resonance angiography (MRA) studies on these 2000 subjects at the same time MRI images are being acquired for ARIC-NCS. We will measure luminal stenosis, a standard clinical parameter for ICAS, using MRA. In addition, we will measure intracranial vessel wall thickness, using a novel high-resolution MRI sequence. Vessel wall thickness may detect atherosclerotic changes without any significant stenosis and may be a better measure of atherosclerotic disease burden. In addition, compared to luminal stenosis, vessel wall thickness may also be more strongly associated with cognitive impairment or dementia. We will use two different definitions of ICAD to determine prevalence 1. luminal narrowing of >50%, and 2. vessel wall thickness of >0.6-mm. Implications. The study is based on new data that suggests asymptomatic ICAD is associated with cognitive impairment among elderly persons in the general population. Furthermore, asymptomatic ICAD may be associated with cognitive impairment in the absence of cerebral infarctions on MRI due to chronic hypoperfusion in the elderly population. This will also be the first study to determine the prevalence of asymptomatic ICAD in the US elderly population and its impact upon cognitive impairment.