Psychiatry Research EG

Introduction High comorbidity with anxiety disorders has been reported in bipolar disorder (BPD). The presence of comorbid anxiety often complicates the presentation and the course of BPD. Bipolar I disorder is associated with abnormal filtering of sensory information at an early, preattentive level as shown by diminished gating of the auditory-evoked P50 potential assessed by a paired-click paradigm. Objective This study aims to compare patients with BPD and anxiety disorder, patients with BPD without anxiety disorder, and controls in terms of the auditory-evoked potential. Participants and methods This was a cross-sectional and case–control study with a convenient sampling. After obtaining consent from the ethical committee in Kasr Al-Ainy hospital, the population of this study was divided into three groups. The first group included 30 patients with bipolar I disorder and comorbid anxiety disorder according to the Diagnostic and Statistical Manual Classification of Mental Disorder, 4th ed. (DSM-IV). The second group included 30 patients with bipolar I disorder with no other comorbid axis I diagnosis. The patients in the two groups were of both sexes and ranged in age from 20 to 50 years. We excluded those with other psychiatric comorbidities and major medical diseases. They were selected consecutively from among outpatients and inpatients of Kasr Al-Ainy Psychiatry and Addiction Hospital of Cairo University. The third group included 30 individuals (healthy volunteers) matched for age, sex, and socioeconomic status, with no history for any psychiatric disorders. All patients were subjected to the Structured Clinical Interview for DSM-IV Axis I Disorders, the Hamilton Anxiety Rating Scale, and the paired-click paradigm. Results Patients with BPD showed higher suppression in P50, N100, and P200 waves than BPD patients with comorbid anxiety, which is also higher than that among the controls. Conclusion Impaired sensory gating in BPD patients was marked by suppression in P50, N100, and P200 waves of the auditory-evoked potential (paired-click paradigm). Comorbid anxiety disorders lead to a higher suppression in the P50, N100, and P200. Keywords: auditory-evoked potential, anxiety disorder, bipolar disorder