Possible relationship between electroencephalogram finding and lithium response in bipolar disorder

The relationship between electroencephalogram (EEG) finding and lithium response was retrospectively examined in 58 patients with bipolar disorder. All necessary information was obtained from the clinical charts. The patients were categorized into two groups (responder or nonresponder) with regard to the lithium response and into three groups (normal, borderline, or abnormal) concerning the EEG finding. The information both on EEG and lithium response could be obtained from 27 patients. Only five cases were classified as lithium responders. None of these five responders had abnormal EEG finding, while all of five patients with abnormal EEG finding were categorized into nonresponder. No statistically significant interaction was detected between EEG finding and lithium response. This retrospective study suggests that epileptiform EEG abnormality is worth studying further as a possible predictor of lithium resistance in bipolar disorder.