Effect of written emotional disclosure on secondary hyperalgesia in women with trauma history.

Objective: This study investigated the effects of written emotional disclosure on a model of chronic pain in healthy women with and without trauma history.

Method: Participants were prescreened for their trauma history (N = 78) and randomized to a disclosure or a control writing condition. Pain testing occurred either 1 day or 1 month after disclosure. Capsaicin was applied to the forearm to evoke spontaneous burning pain at the application site and mechanical secondary hyperalgesia in the surrounding untreated skin.

Results: As hypothesized, the effect of disclosure on the area and intensity of secondary hyperalgesia depended on trauma history and time of testing (F(1,69) ≥ 7.37, p = .008). Disclosure increased secondary hyperalgesia in participants with trauma history compared with those without trauma when testing occurred 1 day after writing (F(1,69) ≥ 5.27, p ≤ .025), whereas the opposite pattern was observed 1 month later (F(1,69) ≥ 4.88, p ≤ .031). Of the participants with trauma history in the disclosure condition, secondary hyperalgesia was reduced at 1 month compared with 1 day after writing (p = .001). Moreover, greater use of positive emotional words predicted reduced secondary hyperalgesia at 1 month (β = -0.71, p = .022). In contrast, disclosure had no effect on spontaneous pain.

Conclusions: Disclosure modulates secondary hyperalgesia observed in women with trauma history, producing a short-term enhancement and a long-term reduction. This suggests that disclosure has a long-term protective effect that reduces sensitization of pain, which may explain the therapeutic effects of disclosure in patients with chronic pain.