Amplitude/intensity functions of auditory event-related potentials predict responsiveness to bupropion in major...

Patients diagnosed with major depressive disorder (MDD) and enrolled in an open-label safety surveillance study of a sustained release formulation of bupropion hydrochloride (100 to 300 mg/day) were evaluated with the Hamilton Rating Scale for Depression (HAM-D) immediately before and 6 to 12 weeks after the initiation of drug treatment. Auditory event-related potentials (ERPs) recorded under a stimulus intensity modulation paradigm were also obtained at these times. Patients were classified as responders and nonresponders based on post-treatment HAM-D scores, with responders having HAM-D scores less than 10 and nonresponders having scores greater than 10. Consistent with our previous findings, responders exhibited significantly larger positive slope coefficients for P2 ERP component amplitudes as a function of auditory stimulus intensity obtained at baseline and were not affected by bupropion treatment. Thus, these results further support our previous finding that ERP amplitude/intensity functions measured under a stimulus intensity modulation paradigm provide information about the likelihood of a positive therapeutic response to antidepressant pharmacotherapy in patients with MDD and extends these results to bupropion, a pharmacologically atypical antidepressant agent.