Neuropsychological performance in youth with obsessive-compulsive disorder.

There is a paucity of literature on neuropsychological functions in youth with obsessive-compulsive disorder (OCD). Most studies have small sample sizes and have yielded inconsistent results. A recent meta-analysis failed to identify any significant impairments. We studied neuropsychological functions (attention, verbal fluency, working memory, set-shifting, response inhibition, planning and visuospatial abilities) in a large sample of youth with OCD (n = 97) in comparison with controls who did not have OCD (n = 50). After controlling for the confounding effects (age, sex, severity of depression and anxiety, presence of comorbid attention-deficit hyperactivity disorder, any tic disorder, number of comorbidities, and non-verbal intelligence measured by the standard progressive matrices), the youth with OCD significantly underperformed with large effect sizes compared to controls, only on the test of 'behavioral reversal', measured by the Object Alternation Test (trials to reach criterion p < 0.001, Cohen's d = 1.49; perseverative errors p < 0.001, Cohen's d = 1.31). Patients also underperformed on a task of planning, but it was statistically insignificant. Certain comorbid disorders, antipsychotic use and age of onset did not influence neuropsychological performance significantly. Our study demonstrates that youth with OCD may have impaired 'set-shifting' in the form of 'behavioral reversal' and possibly planning, findings broadly consistent with the literature in adults and with the fronto-striatal model of OCD. It is possible that youth may accumulate more neuropsychological impairments over a period, as the illness continues into adulthood.