Department of Epidemiology, Brown University, Providence, RI 02912, USA.
Stroke. 2013 Jun;44(6):1532-6. doi: 10.1161/STROKEAHA.111.000395.
Short-term elevations in fine particulate matter air pollution (PM2.5) are associated with increased risk of acute cerebrovascular events. Evidence from the peripheral circulation suggests that vascular dysfunction may be a central mechanism. However, the effects of PM2.5 on cerebrovascular function and hemodynamics are unknown.
We used transcranial Doppler ultrasound to measure beat-to-beat blood flow velocity in the middle cerebral artery at rest and in response to changes in end-tidal CO2 (cerebral vasoreactivity) and arterial blood pressure (cerebral autoregulation) in 482 participants from the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly (MOBILIZE) of Boston study. We used linear mixed effects models with random subject intercepts to evaluate the association between cerebrovascular hemodynamic parameters and mean PM2.5 levels 1 to 28 days earlier adjusting for age, race, medical history, meteorologic covariates, day of week, temporal trends, and season.
An interquartile range increase (3.0 µg/m(3)) in mean PM2.5 levels during the previous 28 days was associated with an 8.6% (95% confidence interval, 3.7%-13.8%; P<0.001) higher cerebral vascular resistance and a 7.5% (95% confidence interval, 4.2%-10.6%; P<0.001) lower blood flow velocity at rest. Measures of cerebral vasoreactivity and autoregulation were not associated with PM2.5 levels.
In this cohort of community-dwelling seniors, exposure to PM2.5 was associated with higher resting cerebrovascular resistance and lower cerebral blood flow velocity. If replicated, these findings suggest that alterations in cerebrovascular hemodynamics may underlie the increased risk of particle-related acute cerebrovascular events.
短期细颗粒物(PM2.5)空气污染的升高与急性脑血管事件风险的增加有关。来自外周循环的证据表明,血管功能障碍可能是一个核心机制。然而,PM2.5 对脑血管功能和血液动力学的影响尚不清楚。
我们使用经颅多普勒超声测量 482 名来自波士顿的维持平衡、独立生活、智力和老年人活力(MOBILIZE)研究参与者的大脑中动脉在休息时和对呼气末二氧化碳(脑血管反应性)和动脉血压(脑自动调节)变化的逐拍血流速度。我们使用具有随机主体截距的线性混合效应模型,根据年龄、种族、病史、气象协变量、星期几、时间趋势和季节,调整前 28 天平均 PM2.5 水平与脑血管血流动力学参数之间的关联。
前 28 天平均 PM2.5 水平增加一个四分位间距(3.0μg/m3)与脑血管阻力增加 8.6%(95%置信区间,3.7%-13.8%;P<0.001)和休息时血流速度降低 7.5%(95%置信区间,4.2%-10.6%;P<0.001)相关。脑血管反应性和自动调节的测量值与 PM2.5 水平无关。
在这个社区居住的老年人队列中,PM2.5 的暴露与较高的静息脑血管阻力和较低的脑血流速度有关。如果得到复制,这些发现表明,脑血管血液动力学的改变可能是与颗粒相关的急性脑血管事件风险增加的基础。