Cognitive functioning in medication-free obsessive-compulsive patients treated with cognitive-behavioural therapy

• After CBT, OCD patients had significantly improved neuropsychological test results.
• There was no association of neuropsychological and clinical variables with treatment outcome.
• Results indicate that cognitive dysfunctions in OCD are in part state-dependent.
• Results suggest that CBT is effective independent of pre-treatment cognitive dysfunctions.

So far it is still uncertain whether neuropsychological test results in obsessive-compulsive disorder (OCD) change after CBT and whether neuropsychological and clinical variables predict response to CBT. 60 medication-free patients hospitalised for severe OCD were treated with CBT including exposure and response prevention (ERP). Pre- and Post-treatment patients completed a cognitive test battery covering a broad range of neuropsychological and clinical variables. The Yale Brown Obsessive Compulsive Scale (Y-BOCS) was used to assess symptom severity. A healthy control group matched for age, gender, intelligence and education completed the same neuropsychological test battery, with similar test–retest intervals as the patients. Analyses showed significantly worse cognitive functioning in patients compared to healthy controls before treatment on many measures. After CBT patients had significantly improved test results regarding speed of information processing, verbal fluency, visuo-constructive functions and set shifting ability while controls did not perform better at the second testing. None of the neuropsychological and clinical variables assessed was significantly correlated with treatment outcome. These results indicate that cognitive dysfunctions in OCD are in part state-dependent and reversible after treatment. Moreover, our results suggest that CBT is successful even in those patients who exhibit cognitive dysfunctions and who are severely affected at the beginning of treatment.