Do partner handholding effects linger? Order effects of handholding support on mechanical hypersensitivity in women.

Introduction: Social support, such as handholding from a romantic partner, can reduce pain and physiological responses to noxious stimuli. We previously demonstrated that handholding during the induction of secondary mechanical hypersensitivity via electrical stimulation reduces the spatial spread of hypersensitivity. However, real-life social contexts are dynamic, and it remains unclear whether such support has lingering effects after its withdrawal or whether prior support buffers against subsequent absence. Objectives: In this preregistered study, we expanded our earlier sample (N = 37 couples) by adding 28 couples (total N = 65) to examine the effects of partner handholding and condition order on mechanical hypersensitivity. Methods: Healthy women underwent 2 sessions (support and alone), which involved romantic partner handholding during middle frequency stimulation (MFS) of the volar forearm. We measured the perceived intensity, unpleasantness, and spatial spread of hypersensitivity before and after MFS. Results: Handholding significantly reduced both vertical and horizontal spread of hypersensitivity, regardless of condition order. Subjective ratings of pain intensity and unpleasantness revealed a complex interaction with condition order. Elevated baseline mechanical sensitivity and MFS ratings were observed when handholding was provided first, while receiving handholding after having been alone yielded the lowest ratings, consistent with safety signaling or relief effects. The post-MFS increase in ratings was inversely related to baseline sensitivity, resulting in no significant differences. Conclusion: Our findings suggest that although the modulation of hypersensitivity spread by handholding is robust and order-independent, processes related to expectation and habituation shape subjective reports of hypersensitivity and their modulation by handholding.