Background: Arousal dysregulation is assumed to play a pivotal role in the pathogenesis of fatigue in different syndromes. A high proportion of post-COVID patients suffer from persisting fatigue, attentional and autonomic dysfunction. We assumed that in post-COVID syndrome an underlying hypoarousal would be expressed by a combination of interrelated symptoms on different levels: i.e. reduced attentional alertness at the neurocognitive level, the feeling of mental fatigue at the subjective symptom level and decreased tonic central nervous activity at the neurophysiological level.
Method: 40 Post-COVID patients and 40 matched controls were assessed. As a neurocognitive measure of arousal we quantified the parameter visual processing speed C (VPS) based on Bundesen’s “Theory of Visual Attention” (1990) that reflects the alertness state of a given participant. The subjective symptom level was assessed with the Fatigue Assessment Scale. As a measure of arousal at the neurophysiological level, pupillary unrest (PUI) was assessed via the pupillographic sleepiness test in the post-COVID group.
Results: We found that VPS was significantly reduced in post-COVID patients compared to healthy controls. Furthermore, regression analysis revealed that self-rated mental fatigue and PUI explained 34% of variance in VPS.
Conclusion: Our findings corroborate the hypothesis that a virus- or immune-mediated arousal dysregulation in post-COVID patients leads to I) slowing of processing speed at the neurocognitive level, II) reduced arousal at the neurophysiological level and III) a feeling of mental fatigue at the subjective experience level. Further discerning underlying mechanisms and finding treatment strategies by tagerting arousal dysfunction is essential.