Etiology, prevalence, and development of a novel treatment for body dysmorphic disorder

Body dysmorphic disorder (BDD) is characterized by an intense preoccupation with perceived defects in physical appearance that are not noticeable, or only appear slight to others. While effective treatment for this disorder does exist (e.g. cognitive behavioural therapy; CBT) most sufferers do not get access to it. BDD usually begins during adolescence but few studies have explored the prevalence and pattern of comorbidities in this age group. Moreover, the etiology of dysmorphic concerns in young people is unknown. The aims of this thesis were therefore to develop a novel therapist-guided internet-based CBT program for BDD (BDD-NET), with the intention to increase availability of CBT for BDD, and to conduct a genetic epidemiological study of BDD symptoms in adolescents and young adults. In Study I, the feasibility of BDD-NET was evaluated in a sample of 23 self-referred adults diagnosed with BDD. Large and significant reductions in BDD symptoms were observed after treatment, and participants deemed the treatment as highly acceptable. In Study II, the efficacy of BDD-NET was determined in a single-blind randomized controlled trial. Ninety-four participants with BDD were randomized to BDD-NET or online supportive therapy. BDD-NET was superior to supportive therapy, and 39% of those that had received BDD-NET were in remission, compared to 9% in the control group. All participants in the control group were offered BDD-NET after the controlled follow-up. In Study III, all participants (n=88) that had received BDD-NET in Study II were followed-up for 2-years to evaluate the long-term efficacy of BDD-NET. The treatment effects of BDDNET were sustained in the long-term and at the 2-year follow-up, 56% of participants were in remission. In Study IV, the prevalence of clinically significant BDD symptoms, and risks for co-existing psychopathology were estimated in three population-based twin cohorts at ages 15 (n=6,968), 18 (n=3,738), and 20-28 (n=4,671). A classical twin des