Objective: The aims of this study were to compare and investigate the relationships between cognitive functions, electrophysiological findings, which consist of auditory event related potentials (ERPs), the N100, N200, P200 and P300 and neurological soft signs in OCD patients, their siblings and control subjects and to determine potential endophenotypic markers.
Methods: Thirty-three in- and out-patients who were admitted to the Department of Psychiatry of the Hacettepe University Faculty of Medicine with diagnoses of OCD according to the DSM-IV-TR criteria, 18 siblings and 21 healthy control subjects, who were matched for age, gender and years of education, were included in this study. The Yale-Brown Obsessive-compulsive Symptoms Checklist Scale (Y-BOCS) and the Hamilton Depression Rating Scale (HDRS) were administered to all patients to determine illness severity and comorbid depression. A neuropsychological test battery that included the Trail Making Test Parts A and B (TMT-A, TMT-B, the Weschler Memory Scale Revised Edition Digit Span Forward (DSF), Backward (DSB) and total (DST) tests, the Figural memory test (FMT), verbal şuency tests (the Controlled Word Association Test (CWAT) and the Category Fluency Test (CFT)), the Wisconsin Cart Sorting Test (WCST), the Stroop Test (ST), the Block Design Test (BDT), the Rey Auditory Verbal Learning Test (RAVLT) and the Neurological Evaluation Scale (NES) were administered to all participants. Auditory event related potentials recordings, which consisted of the N100, N200, P200 and P300, were obtained from all subjects.
Results: Comparisons of the three groups indicated that patients performed worse in terms of executive functions and visual motor integration compared to siblings and healthy controls. P200 amplitudes sorted as follows: siblings>patients>controls. The absolute values of the N200 amplitudes sorted as follows: siblings
Conclusions: Neurological examination revealed that working memory, executive functions, verbal memory, verbal şuency, visual motor integration, motor speed, figural memory and P300 and N200 measurements were impaired in OCD patients, and working memory, executive functions and visual motor integration were impaired in the siblings of OCD patients. Thus, executive functions, visual motor integration and P200 and P300 amplitudes, among other factors, seem to be potential endophenotypes in OCD.