Peak alpha frequency is associated with pain severity in Long COVID patients with new-onset chronic pain.

Background: New-onset chronic pain is a common and debilitating symptom of Long COVID (LC) that remains not fully understood in terms of pathophysiology and therapeutic targets. A growing body of evidence in chronic pain syndromes similar to LC demonstrates an association between EEG alpha oscillatory activity and the experience of pain, with clinical studies showing maladaptive changes, particularly a slowing of alpha activity. Aims: This study aims to investigate the association between EEG alpha oscillatory activity and pain perception in new-onset LC-chronic pain. Methods: We recruited 31 individuals (20 females) with a clinical diagnosis of LC reporting new-onset chronic pain and 31 healthy pain-free age- and sex-matched controls. Participants completed questionnaires regarding symptoms and psychological functioning prior to recording eyes-open resting-state EEG. Peak alpha frequency (PAF) and alpha band (8-13 Hz) spectral power were extracted from EEG signals. Results: Lower PAF over the posterior scalp region was significantly associated with higher LC-chronic pain severity when controlling for age, depression and the use of centrally acting medication. This finding was consistent across PAF estimation methods. No differences in PAF were observed between the LC patient group and the healthy pain-free control group. Alpha power did not differ between groups and was not associated with pain severity. Discussion: Together, these findings suggest that PAF may index individual differences in pain severity within LC-associated chronic pain, although the absence of overall patient-control differences indicates that PAF should not be interpreted as a disease-specific biomarker and warrants further longitudinal research.