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