Impaired test performance yet spared neurocognitive functioning in individuals with obsessive-compulsive disorder: the role of performance mediators.

Introduction: Although most studies report neurocognitive deficits in patients with obsessive-compulsive disorder (OCD), important exceptions exist, highlighting the possible role of mediators (e.g., poor motivation). This study investigated neurocognitive functioning and potential influences affecting performance in OCD.

Methods: Forty-three participants (13 OCD patients, 30 healthy controls) were assessed using a battery of neurocognitive tests. During the assessment, the examiner completed the Impact on Performance Scale (IPS) which measures variables that may impact neurocognitive performance.

Results: Pooled neurocognitive performance was lower in OCD patients versus healthy controls at a moderate effect size. Patients performed more poorly on the IPS, particularly the Well-Being During Assessment subscale. Performance differences across the two groups were attenuated to a non-significant small-to-medium effect when the IPS was entered as a covariate. A total of 34% of patients showed scores greater than one standard deviation below the mean compared to 9.63% in healthy individuals. Yet, when a conservative impairment criterion (≥2 standard deviations below the mean) was applied, less than 10% of patients displayed deficits.

Conclusions: Neurocognitive impairment in OCD is likely exaggerated. In addition to considering important mediators researchers should report the percentage of participants displaying performance deficits rather than mean group differences alone; the latter obscures the high percentage of patients without impairment and thus may unduly foster stigma in this population.