Neuroscience Research Program, St. Michael's Hospital, Toronto, Ontario, Canada.
Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, Ontario, Canada.
Brain Behav. 2023 Nov;13(11):e3212. doi: 10.1002/brb3.3212. Epub 2023 Oct 23.
Post-acute coronavirus disease 2019 (COVID-19) syndrome (PACS) is a growing concern, with headache being a particularly debilitating symptom with high prevalence. The long-term effects of COVID-19 and post-COVID headache on brain function remain poorly understood, particularly among non-hospitalized individuals. This study focused on the power-law scaling behavior of functional brain dynamics, indexed by the Hurst exponent (H). This measure is suppressed during physiological and psychological distress and was thus hypothesized to be reduced in individuals with post-COVID syndrome, with greatest reductions among those with persistent headache.
Resting-state blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging data were collected for 57 individuals who had COVID-19 (32 with no headache, 14 with ongoing headache, 11 recovered) and 17 controls who had cold and flu-like symptoms but tested negative for COVID-19. Individuals were assessed an average of 4-5 months after COVID testing, in a cross-sectional, observational study design.
No significant differences in H values were found between non-headache COVID-19 and control groups., while those with ongoing headache had significantly reduced H values, and those who had recovered from headache had elevated H values, relative to non-headache groups. Effects were greatest in temporal, sensorimotor, and insular brain regions. Reduced H in these regions was also associated with decreased BOLD activity and local functional connectivity.
These findings provide new insights into the neurophysiological mechanisms that underlie persistent post-COVID headache, with reduced BOLD scaling as a potential biomarker that is specific to this debilitating condition.
新冠肺炎（COVID-19）后综合征（PACS）是一个日益受到关注的问题，头痛是一种尤其使人虚弱、发病率高的症状。COVID-19 和新冠后头痛对大脑功能的长期影响仍知之甚少，尤其是在非住院人群中。本研究专注于功能大脑动力学的幂律标度行为，由赫斯特指数（H）来表示。该指标在生理和心理压力下会受到抑制，因此假设 COVID-19 后综合征患者的该指标会降低，其中持续头痛患者的降幅最大。
为 57 名患有 COVID-19 的个体（32 名无头痛，14 名持续头痛，11 名已康复）和 17 名患有感冒和流感样症状但 COVID-19 检测呈阴性的对照者采集了静息状态血氧水平依赖（BOLD）功能磁共振成像数据。个体在 COVID-19 检测后平均 4-5 个月进行评估，采用横断面观察性研究设计。
无头痛 COVID-19 组与对照组之间 H 值无显著差异，而持续头痛组的 H 值显著降低，头痛已康复组的 H 值升高，与无头痛组相比。这些影响在颞叶、感觉运动和脑岛等区域最大。这些区域的 H 值降低与 BOLD 活动和局部功能连接减少有关。
这些发现为持续性新冠后头痛的神经生理机制提供了新的见解，BOLD 标度降低可能是这种使人虚弱的病症的特异性潜在生物标志物。
