The Intracranial Atherosclerotic Disease and Cognitive Impairment Study

描述（由申请人提供）：依据。颅内动脉粥样硬化性疾病（ICAD）是美国每年约80，000例患者中风的已知原因。此外，它被怀疑与认知障碍和痴呆症有关。然而，尽管这是一个常见的健康问题，但这种疾病的流行程度尚不清楚。此外，ICAD与认知障碍和痴呆的关联程度尚未研究。我们计划研究ICAD在美国老年人群中的患病率，并确定其与认知障碍和痴呆的关系。目的：我们拟定项目的主要目标是在ARIC-NCS中接受MRI的2000例受试者的子样本中进行辅助研究。目的是1）估计年龄在70-89岁的ARIC参与者中ICAD的患病率，2）确定ICAD是否与痴呆或轻度认知障碍相关。设计/方法：社区动脉粥样硬化风险是NHBLI资助的心血管队列，在过去25年中跟踪了约16，000名45-64岁的受试者。现在，由NHLBI资助的ARIC神经认知研究（ARIC-NCS）将对剩余的7000名受试者中的2000名进行磁共振成像（MRI）。神经认知测试将作为ARIC-NCS的一部分进行，选择用于MRI的2000例受试者样本将包括痴呆受试者（n=358）、轻度认知障碍（MCI）受试者（n=761）和正常受试者（n=878）。我们计划在为ARIC-NCS采集MRI图像的同时，对这2000名受试者进行磁共振血管造影（MRA）研究。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MRI序列测量颅内血管壁厚度。血管壁厚度可以检测到动脉粥样硬化的变化，而没有任何显着的狭窄，可能是一个更好的衡量动脉粥样硬化疾病负担。此外，与管腔狭窄相比，血管壁厚度也可能与认知障碍或痴呆更密切相关。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%，和2.血管壁厚度>0.6毫米。这项研究是基于新的数据，表明无症状的ICAD与一般人群中老年人的认知障碍有关。此外，在老年人群中，无症状ICAD可能与MRI上无脑梗死（由于慢性低灌注）的认知障碍相关。这也将是第一项确定美国老年人群中无症状ICAD患病率及其对认知障碍影响的研究。

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.