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

Abstract

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.

Review of the Midbrain Ascending Arousal Network Nuclei and Implications for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), Gulf War Illness (GWI) and Postexertional Malaise (PEM)

“…The postprovocation data suggest the hypothesis that global cerebral blood flow was altered by exercise but in opposite directions in ME/CFS (elevated towards control levels) in contrast to GWI (reduced after exertion). These data were consistent with reduced cerebral blood flow in ME/CFS [77][78][79] and alterations in neurovascular coupling in GWI [80,81].…”

A high salt meal does not impair cerebrovascular reactivity in healthy young adults

“…Next, a facemask was placed over their mouth and nose to deliver 8% CO 2 , 21% O 2 , balance N 2 (i.e., hypercapnia) for two minutes. This was followed by two minutes of recovery and ended with two minutes of mild hyperventilation to lower P ET CO 2 to ~25 mm Hg (i.e., hypocapnia), as previously described (Deegan et al., 2009; Falvo et al., 2018; Serrador & Freeman, 2017; Serrador et al., 2005). Participants hyperventilated at their own pace, but study staff monitored their pace to ensure that P ET CO 2 was lowered to ~25 mm Hg.…”

The role of the autonomic nervous system in cerebral blood flow regulation in dementia: A review

“…Although not a neurodegenerative disease, Gulf War Illness is associated with cognitive dysfunction and is thought to result from altered cholinergic receptors and PN function (Liu et al, 2011), and autonomic dysfunction is common amongst Gulf War veterans (Haley et al, 2013). dCA is less efficient amongst Gulf War veterans, and CBF reductions are greater during sit-to-stand manoeuvres, although vascular reactivity remains intact (Falvo et al, 2018). However, the link between CA and cognitive dysfunction in the context of autonomic impairment has yet to be investigated.…”