Effects of internet-delivered cognitive behavioral therapy on use of child sexual abuse material: A randomized placebo-controlled trial on the Darknet.

Introduction: The use of child sexual abuse material (CSAM) is an international public health and child protection challenge. Objective: To investigate whether Prevent It, a therapist-supported, internet-delivered, eight-week, cognitive behavioral therapy, reduces CSAM viewing among users. Methods: We conducted a global online single-blind (participants), parallel-group, superiority, randomized, psychological placebo-controlled trial with a one-month follow-up, 2019-2021 (ISRCTN76841676). We recruited anonymous participants, mainly from Darknet forums. Inclusion criteria: age 18+ years, past week CSAM use, and sufficient English language skills; exclusion criteria: severe psychiatric illness or non-serious intent to participate. The main outcome was change in self-reported, weekly viewing time from pre- to post-treatment, according to the Sexual Child Molestation Risk Assessment+. Results: A total of 160 participants (157 male, 2 non-binary, and 1 not reporting gender) from all world regions (age intervals [%]: 18-29 [49]; 30-39 [30]; 40-49 [15]; 50-59 [6]) were randomized (1:1) to Prevent It (N = 80) or Placebo (N = 80). Between-group, intention-to-treat analyses suggested a significantly larger decrease in viewing time in Prevent It participants vs. controls pre- to post-treatment (Prevent It: N = 76, Placebo: N = 78, estimate -0.25, 95 % CI, -0.46 to -0.04, p = .017, Cohen's d 0.18). Negative side effects from treatment were fewer in Prevent It compared to control participants and neither group reported severe adverse events. Conclusion: We provide initial support for the feasibility, efficacy, and safety of Prevent It to reduce CSAM viewing among motivated users. Further research is needed to validate these findings.