Abstract

Background/Objectives: Large-scale dysfunction in the default mode (DMN), salience (SN), and central executive (CEN) networks characterises conditions affecting affective, cognitive, and autonomic regulation. Chronic low back pain (CLBP) shows hyperactive salience signalling, disrupted DMN processing, and impaired executive regulation. Chiropractic adjustments modulate cortical excitability, yet whether these extend to oscillatory reorganisation is unknown. This exploratory secondary analysis aimed to determine whether chiropractic care is associated with frequency- and network-specific changes in source-localised EEG connectivity within and between the DMN, SN, and CEN in adults with CLBP. Methods: Seventy-six adults with CLBP were randomised to chiropractic plus usual care (n = 38) or usual care alone (n = 38). EEG was recorded during resting-state and SEP paradigms at baseline, post-intervention, and four weeks. Source activity was reconstructed with sLORETA and PLI computed across theta, alpha, beta, and gamma bands. For each condition, Fisher-z network-mean PLI was analysed in separate network-by-band linear mixed-effects models with Group, Session, and their interaction as fixed effects and a random intercept for a unique participant identifier; ROI-level changes were examined with cluster-based permutation tests, with inference at the connected-component level. Results: Resting-state alpha-band connectivity within the default mode network was higher in the chiropractic group both immediately after care and at four-week follow-up (both q<0.001), alongside additional frequency- and network-specific effects. Region-level analyses identified a distributed alpha-band network spanning most triple-network regions, in which resting-state connectivity increased in the chiropractic group after care (pFWE=0.003; Holm-adjusted p=0.042). For the somatosensory evoked recordings, no network-level interaction survived multiple-comparison correction; the distributed connectivity changes identified in exploratory region-level analyses are therefore considered preliminary. Conclusions: Chiropractic adjustments are associated with frequency-specific changes in resting-state connectivity within the DMN, SN, and CEN. These findings are hypothesis-generating and require confirmation in adequately powered, pre-registered trials before they can be interpreted as a neurophysiological basis for improvements in pain, mood, fatigue, sleep, or quality of life.

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