The investigators are developing and testing a Smartphone-based cognitive behavioral therapy (CBT) "app" for body dysmorphic disorder (BDD). The investigators hypothesize that app-based CBT for BDD will be feasible and acceptable to individuals with BDD, and will improve body image concerns and related outcomes.

The primary aims of this study are to develop and test the feasibility, acceptability, and preliminary efficacy of a Smartphone-based CBT treatment for adults with BDD. This project aims to solve two healthcare problems: poor access to empirically-supportive treatment for BDD, and challenges of generalizing CBT skills outside therapy sessions. Inadequate treatment access is due to limited professionals offering this specialized treatment, economic barriers, and shame preventing sufferers from seeking in-person care. Mobile app-based CBT would solve this access gap by addressing each of these barriers. Among those who obtain CBT, practicing skills outside of therapy is critical for treatment effectiveness, as BDD symptoms occur around-the-clock and can be most impairing at home. However, BDD patients struggle to use skills without therapists' in-person support. App-based CBT that provides on-hand skills coaching addresses this treatment generalization challenge.

This study involves developing the app-based CBT for BDD treatment, and then investigating the initial feasibility, acceptability, and preliminary efficacy of the app-based treatment in an open pilot trial (N = 10), consisting of 12-weeks of active treatment plus a 6-month follow up period.

Phase 1B (open pilot trial):

Inclusion Criteria:

• At least 18 years of age
• Outpatients
• Meets current diagnosis of primary DSM-5 BDD
• Has score on BDD-YBOCS of ≥ 20
• Currently living in the United States

Exclusion Criteria:

• Psychotropic medication changes within 2 months prior to enrollment
• Participants taking psychotropic medication have to have been on a stable dose for at least 2 months prior to enrollment and not change medication during study period
• Participated in CBT for BDD ever during lifetime
• Current substance dependence
• Lifetime bipolar disorder or psychosis
• Acute, active suicidal ideation
• Current severe comorbid major depression, defined by a PHQ-9 total score ≥ 20
• Personality disorder that could jeopardize treatment participation (e.g., borderline personality disorder with self-harm)
• Concurrent psychological treatment
• Do not own a supported mobile Smart phone with a data plan (currently iPhone 5S or more recent, running iOS 9 or newer)
• Intellectual disability or other cognitive impairment that would interfere with ability to engage in CBT

Adverse event data were collected at mid-treatment (6 weeks), post-treatment (12 weeks), 3-month and 6-month follow-up assessment time-points.