Pediatric obsessive-compulsive disorder (OCD) is a debilitating illness characterized by intrusive thoughts and repetitive behaviors. Patients may exhibit poorer executive function, such as cognitive planning.1 Substantial overlap exists between brain areas implicated in OCD pathology2 and those involved in planning (eg, dorsolateral prefrontal cortex, posterior parietal cortex, extrastriate visual cortex, anterior cingulate cortex, inferior frontal gyrus),3 and functional magnetic resonance imaging (MRI) demonstrates that participants with OCD perform poorly and show less regional brain responsivity as task load increases in comparison to healthy controls.4 This robust finding could be useful in the domain of precision medicine, as it normalizes after cognitive-behavioral therapy5 and may be useful in individual activation profiles that could predict treatment response. However, the finding has never been studied in individual subjects. Here, as a proof of concept, we compare the performance and brain activation of OCD-discordant monozygotic twins during a planning task commonly used in imaging studies,6 the Tower of London (ToL).
