Improvement predictors in obsessive-compulsive disorder. An event-related potential study

The treatment of patients with obsessive-compulsive disorder gives variable and unpredictable results. Numerous clinical features have been investigated as potential predictors of medication response but without consistent results. Preliminary findings have shown that some impairments of pre-treatment event-related potentials (ERPs) could be associated with future treatment outcome (Morault et al., 1997). The present study aimed to confirm the relationships between ERPs and treatment efficacy with larger sample sizes. ERP components were elicited during a verbal auditory 'oddball' paradigm and were recorded in 21 unmedicated patients compared to 21 control subjects. After a pharmacological treatment, the disorder improved in 12 patients. Pre-treatment ERP data were retrospectively compared between treatment responders, non-responders and control subjects. Patients who were to respond favorably to treatment had significantly reduced N2 amplitude and shorter N2 and P3 latencies compared to non-responders and control subjects. In contrast, no difference was shown between non-responders and control subjects. Our findings provide evidence for abnormalities of ERPs which could be considered as potential predictors of treatment response in patients with OCD. These results need to be tested in a prospective protocol.