Effects of replay and rehearsal expressive writing on mental health: a randomized controlled trial.

Background: Expressive writing about previous interactions has been found to improve mental health, but the effect of expressive writing about future imagined interactions has not been explored. Methods: To examine the effects of rehearsal expressive writing on mental health, we recruited 132 people, and 100 (76%) completed writing tasks (31 control, 34 replay, and 35 rehearsal). Each group was measured at baseline, after the 4th consecutive day of 15-minute-per-day writing, and at 1-month follow-up. Measures included psychological adjustment (Mental Health Inventory-18, MHI), self-perceived stress, PROMIS depression and anxiety, work and social adjustment, loneliness, coping (Brief COPE), and daily writing expressiveness. Repeated measures ANOVA examined time and time-by-group effects. Results: Significant time effects were found for MHI, self-perceived stress, depression and anxiety symptoms, and self-blame. Marginally significant group-by-time effects on behavioural disengagement and venting, subscales of the coping measure, were found, with rehearsal associated with decreased disengagement and increased venting compared to the replay group. The rehearsal group consistently reported significantly higher perceived writing expressiveness than the other groups over time. Rehearsal and replay expressive writing showed different effects on writing expressiveness and coping via behavioural disengagement and venting. Conclusion: This study established rehearsal as a promising extension to the affordable therapeutic expressive writing paradigm.