A family study assessing P300 as a probable electrophysiological endophenotype in obsessive-compulsive disorder

Objectives: Endophenotype models of disease would help to clarify both diagnostic classification and etiological understanding of obsessive-compulsive disorder (OCD). The objective of the study is to investigate electrophysiological endophenotypes in OCD. Material and Methods: We recorded P300 on an auditory oddball paradigm for 20 patients with OCD, their 20 first-degree relatives (FDRs), and 20 normal controls (matched with patients). Patients were assessed on the Yale-Brown Obsessive-Compulsive Scale, Hamilton Rating Scale for Anxiety, and Hamilton Rating Scale for Depression. Results: Both patients and FDRs had significantly shorter P300 latencies as compared to normal controls in all regions assessed ( P < 0.01). Significantly smaller centro-parietal ( P < 0.01) P300 amplitude on auditory oddball paradigm was found in patients and FDRs as compared to normal controls. Conclusion: Shorter P300 latency representing increased processing speed and smaller P300 amplitude reflective of dysfunctional response inhibition are suggested to mediate genetic risk for OCD and proposed as possible electrophysiological endophenotypes for OCD.