Respiratory Peridocity and Cognitive Decline in Elders

实验室和临床研究结果表明，低脑氧合状态与老年人的认知能力下降和痴呆有关。 睡眠是缺氧事件风险增加的时期;低呼吸周期性可能是识别睡眠期间脑氧合低的个体的重要指标。 我们以前的研究表明，呼吸周期性较低的老年人有更多的碎片睡眠，更多的低振幅δ睡眠和睡眠期间大脑氧合的更大下降。 这项纵向观察研究的目的是：（1）检查呼吸周期性、睡眠结构和睡眠期间脑氧合测量之间的关系;（2）检查睡眠期间呼吸周期性或脑氧合是否单独或联合预测24个月内的认知能力下降;（3）探讨24个月内呼吸周期和脑氧合的变化。将在基线以及12个月和24个月时对106名70岁以上的社区居住老年人进行评价。将根据呼吸感应体积描记器波形测量呼吸周期性，包括呼吸周期持续时间（sdIBI）、频率（sdIBF）和振幅（sdAMP）变异性的平均5分钟测量值。 标准的多导睡眠图方法将用于测量睡眠结构，包括睡眠状态的比例，以及睡眠纺锤波之间的平均间隔，睡眠-觉醒转换，觉醒和K复合波。 双（右-左）脑血氧饱和度测定将用于测量平均5分钟左右脑血氧饱和度相对于静息清醒基线的最大变化。 将在睡眠研究的同时测量次级记忆、工作记忆和注意力的标准化测试，以描述认知功能的变化，并检查呼吸周期性或脑氧合单独或组合是否可预测24个月内的认知下降。 此外，我们将探讨呼吸周期和脑氧合如何随着时间的推移而变化和相互作用。 将每6个月测量一次睡眠质量、脑血管风险因素、体力活动和抑郁症状的数据，因为这些指标可能会迅速变化，并可能影响关键结局指标。 除作为对照组外，未表现出认知功能下降的受试者的数据将用于探索性分析，以确定呼吸周期性和脑氧合的性别和人种相关差异。 由于对老年人使用脑血氧测定法进行呼吸周期性或脑氧合了解甚少，因此这项前瞻性研究将为确定这些变量如何变化提供重要数据，并可用于预测经过仔细筛选的老年人样本中的认知能力下降。

Laboratory and clinical findings suggest that states of low cerebral oxygenation are associated with cognitive decline and dementia in older adults. Sleep is a period of increased risk for hypoxic events; and low respiratory periodicity may be an important indicator for identifying individuals with low cerebral oxygenation during sleep. Our previous studies suggest that older adults with low respiratory periodicity have more fragmented sleep, more low amplitude delta sleep and greater declines in cerebral oxygenation during sleep. The aims of this longitudinal observational study are (1) to examine the relationship between measures of respiratory periodicity, sleep structure and cerebral oxygenation during sleep; (2) to examine whether respiratory periodicity or cerebral oxygenation during sleep, alone or in combination, predict cognitive decline over 24 months; and (3) to explore how changes in respiratory periodicity and cerebral oxygenation change over 24 months. One hundred and six community dwelling older adults, age 70+ years, will be evaluated at baseline and at 12-and 24-months. Respiratory periodicity will be measured from the respiratory inductance plethysmograph waveform and include the average 5- minute measures of the variability in the duration (sdIBI), frequency (sdIBF) and amplitude (sdAMP) of breathing cycles. Standard polysomnographic methods will be used to measure sleep structure, which include the proportion of sleep states, as well as the mean interval between sleep spindles, sleep-wake transitions, arousals, and K-complexes. Dual (right- left) cerebral oximetry will be used to measure maximum change in the average 5-minute right and left cerebral oxyhemoglobin saturation from resting awake baseline. Standardized tests of secondary memory, working memory, and attention will be measured at the same time as the sleep studies in order to describe changes in cognitive function and to examine whether respiratory periodicity or cerebral oxygenation alone or in combination predict cognitive decline over 24 months. In addition, we will explore how respiratory periodicity and cerebral oxygenation change and interact over time. Data on sleep quality, cerebrovascular risk factors, physical activity and depressive symptoms will be measured every 6 months because these measures can change rapidly and may affect the key outcome measures. In addition to serving as a comparison group, data from subjects who do not exhibit cognitive decline will be used in exploratory analyses to determine gender and race-associated differences in respiratory periodicity and cerebral oxygenation. Since little is known about respiratory periodicity or cerebral oxygenation using cerebral oximetry in older adults, this prospective study will provide important data for determining how these variables vary and may be used to predict cognitive decline in a carefully screened sample of older adults.