Lower Resting-State Alpha Reactivity in Chronic Widespread Pain Compared to At-Risk and Healthy Individuals

BackgroundChronic widespread pain (CWP), the hallmark of Fibromyalgia (FM), is poorly understood. Altered spectral power of cortical oscillations during rest have been identified in chronic pain, yet it is unknown whether people at high risk of future CWP show FM-like Electroencephalogram (EEG) features. This cross-sectional observational study is the first to examine spectral changes in individuals at high risk of CWP.MethodsDifferences in resting-state oscillatory power in FM (n = 19), At-Risk (AR; n = 21) and Healthy Control (HC; n = 17) groups were examined. Risk factors included non-CWP pain, somatic symptoms, illness behaviour and sleep problems. Patients were not on centrally acting medication. EEG recordings were obtained in eyes-open and closed conditions (6 min of each) to assess alpha reactivity (eyes-closed minus eyes-open). Group differences in scalp-averaged spectral power were examined in several frequency bands, and topographic analysis was performed on alpha.ResultsAlpha reactivity was significantly lower in FM compared to AR and HC groups. Topographic analysis of alpha found that this interaction peaked in right-frontal electrodes, where there was a positive (uncorrected) correlation between alpha reactivity and morning salivary cortisol levels in AR individuals, not present in FM.ConclusionsAs expected, alpha reactivity differed between groups; however, contrary to our expectations, AR did not show FM-like resting alpha physiology, but were instead similar to HC. The (uncorrected) positive association of right-frontal alpha reactivity and cortisol hints at a pattern related to resilience to CWP in high-risk individuals, which larger, perhaps longitudinal studies may confirm.