Development of novel and accessible treatments for trichotillomania and skin-picking disorder

Abstract: Background: Trichotillomania (TTM) and Skin-picking disorder (SPD) are psychiatric conditions characterized by recurrent and excessive hair-pulling and skin-picking, respectively. These behaviors result in significant hair loss or skin lesions and often consume substantial amounts of time, leading to significant distress and functional impairment. Prevalence rates vary across studies but have been demonstrated to be as high as 3.5% for TTM and 5% for SPD. The recommended first-line treatment for TTM and SPD is behavior therapy (BT). Unfortunately, healthcare practitioners often lack sufficient knowledge about these disorders, limiting the availability of treatments, particularly for individuals in geographically distant areas. Group therapy offers a potential solution, allowing caregivers to treat more people in the same timeframe. Further enhancement of availability can be achieved through online delivery. While therapist-supported internet-delivered behavior therapy (iBT) has been extensively studied for related disorders, treatments specifically for TTM and SPD have only been explored through unguided or minimally supported online interventions, yielding modest effect-sizes. Objective: The thesis aimed to develop and evaluate formats for delivering BT to increase availability and accessibility for these disorders. Specifically, we aimed to: 1) test the feasibility and preliminary efficacy of ACT-enhanced group behavior therapy (AEGBT) for TTM and SPD in an open pilot study, 2) test the feasibility and preliminary efficacy iBT for TTM and SPD in an open pilot study, 3) explore the participants experiences of iBT for TTM and SPD in a qualitative study, and 4) test the feasibility and efficacy of iBT for adult patients with SPD compared to a wait-list condition in a randomized trial. Methods: In Study I, based on the original protocol for individual face-to-face therapy we developed AEGBT and conducted an open pilot study with 40 adult participants with TTM and/or SPD in mixed diagnosis groups to test the feasibility and preliminary efficacy of the treatment. In Study II, we developed iBT and conducted an open pilot study with 25 adult participants with TTM and/or SPD to test the feasibility and preliminary efficacy of the treatment. Both Study I and II were conducted in routine psychiatric care. In Study III, we explored the participants’ experiences of undergoing iBT in a qualitative study. In Study IV, conducted in an academic setting, we randomized 70 participants with SPD to either iBT or a waitlist of equal duration. Results: Study I demonstrated high group attendance and minimal treatment drop-out. AEGBT produced significant decreases in hair-pulling and skin-picking severity from pre- to post-treatment, with moderate to large within-group effects from d = 0.77 to 1.24. Symptom reduction was sustained for SPD participants, but not for those with TTM at the 12-month follow-up. The utilization of a group format allowed therapists to efficiently manage 25% more patients in comparison to an individual treatment format. Study II reported high levels of participant satisfaction and iBT credibility, reflected in high average module completion and few participants ending treatment prematurely. iBT resulted in significant decreases in hair-pulling and skin-picking severity with effect sizes ranging from d = 0.89 to 1.75. Similar to Study I, long-term efficacy favored SPD participants. Study III, identified five over-arching themes, unveiling that participants perceived iBT as beneficial and efficacious, albeit time-consuming, leading to stress in some. The treatment's flexibility was appreciated by some participants, while others expressed a need for increased support. Study IV demonstrated a significantly greater improvement in SPD symptoms in the iBT group compared to the control group at post-treatment, with a between-group effect-size in the large range (bootstrapped d = 1.3). The improvement compared to pre-treatment remained significant at the 6-month follow-up. Conclusions: In conclusion, both AEGBT and iBT proved to be effective, feasible, and safe treatment approaches for TTM and SPD in routine psychiatric care. iBT, while advantageous, presented challenges for participants. Tailoring the treatment to individual needs or blending iBT with face-to-face treatment could enhance efficacy and applicability. Additionally, iBT demonstrated preliminary efficacy and sustained long-term benefits for SPD compared to a passive control condition. Directions for future research includes evaluating AEGBT and iBT in studies with larger sample sizes and active control conditions alongside cost-effectiveness analyses comparing face-to-face behavior therapy versus these novel treatment approaches. Furthermore, in order to enable nationwide access to BT for individuals with TTM and SPD, evaluations of the implementation of these approaches in regular healthcare is needed.