Treatment effectiveness for comorbid anorexia nervosa and obsessive-compulsive disorder: a systematic review

Objective: Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are severe, commonly co-occurring disorders. AN and OCD comorbidity is associated with worsened prognosis and treatment responses, so better understanding treatment efficacy across both disorders could improve outcomes. We conducted the first known systematic review of non-pharmacological treatment efficacy for comorbid AN and OCD. Methods: A systematic review of PubMed, PsycNet, Scopus, ProQuest and Google Scholar, up to and including January 2024, yielded 14 studies. PRISMA methodology was used. The study was preregistered (PROSPERO CRD42024507762). Results: AN symptoms tended to improve while OCD symptoms did not. Most studies looked at treatments developed for AN. Studies examined a range of treatment types (e.g., deep brain stimulation and family-based therapy), study types (e.g., case study, single-arm and randomised controlled trial) and spanned all levels of care. Participants were mostly patients with AN, and many also had OCD symptoms. Risk-of-bias was variable. Conclusion: Current treatments may be effective for AN but not for comorbid OCD symptoms. More research is needed examining comorbid AN and OCD treatment, particularly with more severe OCD. Future efforts should investigate transdiagnostic treatments, utilisation of OCD treatments for AN and longitudinal designs to examine relapse in addition to remission.