We describe a case whereby a 15-year-old female with treatment-resistant obsessive-compulsive disorder (OCD) was treated with methylphenidate for co-morbid attention deficit hyperactivity disorder (ADHD). The ADHD-OCD co-morbidity has often been overlooked clinically due to conflicting opinions about their underlying neurobiology and treatment options.

In this adolescent with co-morbid ADHD and OCD, we observed that the adjunctive use of methylphenidate resulted in enhanced treatment response to both psychological and pharmacological interventions for OCD. This case highlights the need to identify and treat co-morbid ADHD in OCD cases where progress has stalled.