Dynamic cerebral autoregulation is impaired in Veterans with Gulf War Illness: A case-control study

Neurological dysfunction has been reported in Gulf War Illness (GWI), including abnormal cerebral blood flow (CBF) responses to physostigmine challenge. However, it is unclear whether the CBF response to normal physiological challenges and regulation is similarly dysfunctional. The goal of the present study was to evaluate the CBF velocity response to orthostatic stress (i.e., sit-to-stand maneuver) and increased fractional concentration of carbon dioxide. 23 cases of GWI (GWI+) and 9 controls (GWI) volunteered for this study. Primary variables of interest included an index of dynamic autoregulation and cerebrovascular reactivity. Dynamic autoregulation was significantly lower in GWI+ than GWI- both for autoregulatory index (2.99±1.5 vs 4.50±1.5, p = 0.017). In addition, we observed greater decreases in CBF velocity both at the nadir after standing (-18.5±6.0 vs -9.8±4.9%, p = 0.001) and during steady state standing (-5.7±7.1 vs -1.8±3.2%, p = 0.042). In contrast, cerebrovascular reactivity was not different between groups. In our sample of Veterans with GWI, dynamic autoregulation was impaired and consistent with greater cerebral hypoperfusion when standing. This reduced CBF may contribute to cognitive difficulties in these Veterans when upright.已有研究报道，海湾战争病（Gulf War Illness, GWI）患者可出现神经功能障碍，其中包括毒扁豆碱激发试验下的脑血流量（cerebral blood flow, CBF）反应异常。然而目前仍不明确，机体对正常生理应激的CBF反应及调控是否同样存在功能异常。本研究旨在评估受试者在直立位应激（即坐立转换动作）与吸入二氧化碳分数浓度升高时的CBF速度变化反应。本研究共招募23例确诊海湾战争病患者（记为GWI+组）与9例健康对照者（记为GWI-组）参与试验。本研究关注的核心观测变量包括动态自身调节指数与脑血管反应性。GWI+组的动态自身调节指数显著低于GWI-组：两组分别为2.99±1.5与4.50±1.5，p=0.017。此外，我们观察到，GWI+组在站立后血流最低点的CBF速度降幅（-18.5±6.0% 对比 -9.8±4.9%，p=0.001）以及稳态站立阶段的CBF速度降幅（-5.7±7.1% 对比 -1.8±3.2%，p=0.042）均显著大于GWI-组。与之相对，两组的脑血管反应性并无显著差异。在本研究纳入的海湾战争病退伍军人样本中，动态自身调节功能受损，且站立时伴随更为显著的脑低灌注。这种CBF水平降低可能是导致该类退伍军人直立位时出现认知困难的潜在诱因。