Soothing touch in chronic pain: investigating the beneficial effects of Affective Touch in Fibromyalgia

Fibromyalgia (FM) is a debilitating syndrome characterized by diffuse chronic pain in the absence of identifiable organic causes. Among numerous proposed hypotheses, FM has been conceptualized as a central sensitization syndrome, suggesting that the heightened experience of pain may arise from altered processing of nociceptive stimuli. Recent studies have shown that gentle, caress-like touch, mediated by C-tactile (CT) afferents, exerts soothing and pain-ameliorating effects in conditions of acute pain, pointing to a likely interaction between nociceptive and affective-tactile systems. In line with these findings, the present research extends this investigation to a syndrome hallmarked by chronic pain, namely FM. Study 1 first aimed to determine whether CT-mediated Affective Touch and other basic somatosensory functions were preserved in FM patients compared to healthy controls. Participants underwent screenings of tactile acuity, tactile sensitivity, heat pain threshold, and interoceptive accuracy, and were asked to evaluate the perceived pleasantness of CT-optimal (3cm/s) and non-CT-optimal (30cm/s) stimulations. With the exception of increased heat pain sensitivity in FM patients, the two groups were comparable across all other functions, including a preserved preference for CT-optimal touch. In Study 2, an intervention protocol was developed to investigate the beneficial effects of prolonged CT-optimal stimulation on pain perception and autonomic regulation in FM. The protocol involves 16 minutes of continuous CT-targeted touch, with preliminary outcomes focusing on pain reduction and increased Heart Rate Variability (HRV). Overall, these findings suggest that CT-mediated Affective Touch represents a preserved and potentially clinically relevant mechanism for non-pharmacological pain modulation in FM.