Auditory P300 event related potential acid serotonin reuptake inhibitor treatment in obsessive-compulsive disorder patients

Neuropsychological findings in obsessive-compulsive disorder (OCD) have bee n explained in terms of reduced cognitive shifting ability as a result of l ow levels of frontal inhibitory activity. This deficit could be reflected i n an abnormal P300 component of the event-related potential. The improvemen t in cognitive processing due to pharmacological treatment would modify the P300 component, bringing it close to that of normal controls. Nineteen pat ients suffering from OCD and 19 normal controls were recorded. We used a co mputerized version of the auditory 'odd-ball paradigm' to obtain the P300 c omponent at the Pt electrode. Patients were tested twice, drug-free and und er treatment with clomipramine in 250-300 mg doses. We observed the P300 co mponent to have lower amplitude and longer latency in drug-free OCD patient s when compared with controls. P300 amplitude in OCD increased after treatm ent, although this was supported only by a statistical trend. There was no modification in P300 latency after treatment. It is possible that inhibitor y activity improves with treatment and allows patients to answer with more confidence, which results in an increase in P300 amplitude. This study sugg ests that cognitive dysfunction in OCD fluctuates with changes in the clini cal associated with treatment, probably in relationship to central serotoni nergic transmission. (C) 2001 Elsevier Science Ireland Ltd. All rights rese rved.