Does EEG predict response to valproate versus lithium in patients with mania?

A number of factors may suggest that a patient with mania may respond to valproate or to lithium. However, prediction of which patients will respond to either medication remains difficult. In this study nonepileptiform EEG abnormalities in responders to each medication were investigated. Six of 20 patients (30%) responsive to lithium but not to valproate had nonepileptiform EEG abnormalities while 14 of 20 patients (70%) responsive to valproate but not to lithium had nonepileptiform EEG abnormalities. Patients presenting with mania and EEG abnormalities, particularly sharp activity, are statistically more likely (chi2 = 4.9, df = 1, p = .027) to respond to valproate than to lithium. Whether such a finding will also hold true for other anticonvulsants used to treat mania remains to be seen.