Intelligence quotient (IQ) in pediatric patients with obsessive-compulsive disorder

Abstract

ObjectiveThe aim of the present study was to examine the intellectual quotient (IQ) in a large sample of youth with obsessive-compulsive disorder (OCD) and to compare them with typically developing individuals (TDI), adding to the scarce literature focusing on the intelligence evaluation of this population. MethodThe IQ of 82 children and adolescents with OCD and 82 TDI, matched by age, sex, handedness and education, was assessed by the Wechsler Abbreviated Scale of Intelligence (WASI, Brazilian-version). Statistics were performed with independent t-test, correlations and ANCOVA (controlling for motor and processing speed and comorbidities), corrected using the Benjamini-Hochberg multiple comparisons correction. ResultsNo between-group differences were found on the full-scale IQ (FSIQ, p-value = 0.545) or verbal IQ (VIQ; p-value = 0.423). In contrast, a significant difference was found in the performance IQ (PIQ; p-value = 0.045, Cohen's d = 0.379) and IQ discrepancy, i.e. the difference between VIQ and PIQ (p-value = 0.012, Cohen's d = 0.494). Analyses of the PIQ subtest scores revealed impaired performance in the Block Design test among OCD patients (p-value = 0.012, Cohen's d = 0.273), that remained after correcting for motor and processing speed and comorbidity status. ConclusionIn our sample of pediatric patients with OCD, the FSIQ, VIQ and PIQ were within the average range (90-110), and we did not find between-group differences in the FSIQ or VIQ, indicating that youth with OCD do not present major deficits in intellectual efficiency. Nevertheless, replicating an extensive adult literature, we found lower PIQ scores in youth patients, that were not better explained by motor and processing speed or comorbidity status.