Evidence that implementation intentions reduce self-harm in the community

Implementation intentions are 'IF-THEN' plans that encourage goal-intended behaviour. This study was designed to test whether an intervention encouraging the formation of implementation intentions can reduce self-harm in the community. A randomized controlled design was used. At pre-intervention, outcome variables (self-harm in both specified and unspecified critical situations and suicidality) and potential moderators of implementation intentions (goal intention, mental imagery, and exposure to self-harm) were measured using self-report questionnaires. The participants (N = 469, aged 18-66 years, 86.4% female, 6.8% male and 6.7% other) were then randomized to either an experimental (implementation intention) or control task. At three-months post-intervention, self-report questionnaires were used again to measure the outcome variables. There were no overall differences between the conditions at post-intervention. However, goal intention and mental imagery, but not exposure to self-harm, moderated the effects of condition on self-harm in specified critical situations. At high (mean + 1SD) levels of both goal intention and mental imagery, the experimental condition reported self-harming less frequently in the situations specified in their implementation intentions. Implementation intentions therefore represent a useful intervention for reducing self-harm in specified critical situations for people in the community who wish to avoid self-harm and those who frequently experience self-harm and suicide related mental imagery.