Considerations for the treatment of obsessive-compulsive disorder in patients who have comorbid major depression

IntroductionObsessive-compulsive disorder (OCD) is a debilitating psychiatric disorder that affects a significant number of individuals worldwide. Major depressive disorder (MDD) is among the most common comorbidities reported in people with OCD. The emergence of MDD in individuals with OCD can be attributed to the increased severity of OCD symptoms and their profound impact on daily functioning. Depressive symptoms can also modify the course of OCD.Areas coveredIn this review, the authors explore potential shared neurobiological mechanisms that may underlie both OCD and MDD, such as disturbed sleep patterns, immunological dysregulations, and neuroendocrine changes. Furthermore, they address the challenges clinicians face when managing comorbid OCD and MDD. The authors also discuss a range of treatment options for OCD associated with MDD, including augmentation strategies for serotonin reuptake inhibitors (e.g. aripiprazole), psychotherapy (especially CBT/EPR), transcranial magnetic stimulation (TMS), electroconvulsive therapy (ECT), and deep brain stimulation (DBS).Expert opinionAlthough there is no 'rule of thumb' or universally acceptable strategy in the treatment of OCD comorbid with MDD, many clinicians, including the authors, tend to adopt a unique transdiagnostic approach to the treatment of OCD and related disorders, focusing on strategies known to be effective across diagnoses. Nevertheless, the existing 'cisdiagnostic approaches' still retain importance, i.e. specific therapeutic strategies tailored for more severe forms of individual disorders.