Cerebral peak alpha frequency: Associations with chronic pain onset and pain modulation.

Chronic pain is highly prevalent in the U.S. and leads to myriad negative sequalae and suffering. One way to address chronic pain is to identify who is at risk and intervene prior to symptom onset. Research suggests resting peak alpha frequency (PAF), the speed of alpha oscillations at rest, is slower in healthy individuals with greater pain sensitivity and in chronic pain patients. Thus, slower PAF may denote chronic pain vulnerability. Other research has shown that individuals at higher risk of chronic pain exhibit disrupted pain modulation, i.e., less efficient pain inhibition and increased pain facilitation. Currently, the ability of PAF to predict chronic pain and its relation to pain modulation is under-researched. This investigation aimed to address this gap by characterizing associations between PAF, onset of chronic pain, and pain modulation. Using archival data from three independent studies, this investigation assessed whether slower PAF is associated with prospectively-determined chronic pain onset, decreased pain inhibition (i.e., impaired conditioned pain modulation, impaired erotica-induced pain inhibition), and increased pain facilitation (i.e., increased temporal summation of pain, augmented mutilation-induced pain facilitation). Results show that slower PAF was associated with greater facilitation of spinal (i.e., nociceptive flexion reflex) and supraspinal (i.e., N2 potential) nociception in response to unpleasant pictures (i.e., human injury images). This suggests that slower PAF is associated with threat-enhanced spinal and supraspinal nociception and may be relevant for chronic pain conditions with disrupted threat systems. Slower PAF was not associated with any other pain outcome, including prospectively determined chronic pain onset. However, chronic pain onset could only be assessed in one study with a mixed eyes open/eyes closed recording, limiting the significance of this finding.