An online self-guided cognitive intervention for unwanted intrusive thoughts about harming infants in new parents: initial randomised controlled trial with mediation analysis.

Approximately one-fifth of new parents struggle with unwanted intrusive thoughts (UITs) about intentionally harming their child. This study evaluated the initial efficacy, feasibility and acceptability of a novel online self-guided cognitive intervention for new parents with distressing UITs. Self-recruited parents (N = 43, 93% female, age 23-43 years) of children 0-3 years reporting daily distressing and impairing UITs were randomized to the 8-week self-guided online cognitive intervention or to waiting-list. The primary outcome was change on the Parental Thoughts and Behaviour Checklist (PTBC) from baseline to week 8 (post-intervention). The PTBC and negative appraisals (mediator) were assessed at baseline, weekly, post-intervention and at the 1-month follow-up. Results showed that the intervention led to statistically significant reductions in distress and impairment associated with UITs at post-intervention (controlled between-group d = 0.99, 95% CI 0.56 to 1.43), which were maintained at the 1-month follow-up (controlled between-group d = 0.90, 95% CI 0.41 to 1.39). The intervention was deemed to be feasible and acceptable by the participants. Change in negative appraisals mediated reductions in UITs but the model was sensitive to mediator-outcome confounders. We conclude that this novel online self-guided cognitive intervention can potentially reduce the distress and impairment associated with UITs in new parents. Large-scale trials are warranted.Abbreviations: UITs: Unwanted Intrusive Thoughts PTBC: Parental Thoughts and Behaviour Checklist.