Event-related brain potentials and the ability to focus and shift attention in adults with obsessive compulsive disorder

This study was designed to investigate the effect of shifting attention on behavioral performance, latencies and amplitudes of attention related ERP components in subjects with Obsessive Compulsive Disorder. Twenty-five subjects with OCD and twenty-five control subjects participated in this research effort. Mean age of OCD subjects was 38.92, and mean age of control subjects was 34.36. Subjects were not different with regard to handedness, gender, or socioeconomic status. Subjects denied having seizure disorders, serious medical, neurological or psychiatric illness other than OCD. Subjects were also urine drug screened on the day of testing. Eighteen of the subjects with OCD were unmedicated, while seven were taking selective serotonin reuptake inhibitor medication.;Response accuracy, reaction time, commission error rate, amplitudes and latencies of P3b, and Shifting Difference waves (SD/P700) were measured during two attentional tasks that required focused attention to auditory and visual stimuli, and shifts of attention between auditory and visual stimuli. In addition Y-BOCS measures of symptom severity were gathered from subjects with OCD for correlational analysis. An alpha of.01 was accepted for all calculations in order to lower the risk of Type I error over the entire experiment.;Subjects with OCD exhibited no behavioral deficits or SD/P700 differences when compared with control subjects. Medicated subjects with OCD produced longer latencies than both non-medicated and control subjects during shifting attention tasks. Non-medicated subjects with OCD produced smaller P3b amplitudes than medicated OCD subjects and controls, especially in the visual modality. Symptom severity scores of non-medicated OCD subjects were correlated closely with reduced visual P3b amplitudes. Results suggest a relationship in which increased symptom severity (as measured by Y-BOCS score) is predictive of diminished visual P3b amplitudes. Non-medicated subjects with OCD produced fewer P3b amplitude differences during the more complex shifting attention task than in the focus tasks. Therefore influences such as task complexity and instructional set may differentially impact P3b amplitudes in this clinical population. Both medicated and non-medicated subjects with OCD demonstrated similar deficits in discriminating between target and non-target stimuli as determined by relative measures of P3b amplitudes. Taken together results suggest an auditory attention screening deficit in subjects with OCD rather than a cognitive attention shifting deficit. The additional cognitive effort needed to process intrusive, irrelevant auditory stimuli may result in diminished attentional resources which are available for processing salient stimuli, especially in the visual realm. In this study SSRI medication appeared to be associated with normal P3b amplitudes in subjects with OCD for both the auditory and visual modalities. However, problems discriminating relevant from irrelevant stimuli were found among subjects with OCD regardless of medication status.