The addition of lithium to carbamazepine. Antidepressant efficacy in treatment-resistant depression.

The addition of lithium carbonate to various antidepressant agents, including heterocyclics and monoamine oxidase inhibitors, has been reported to rapidly effect an antidepressant response in otherwise treatment-unresponsive depressed patients. Fifteen depressed patients diagnosed by DSM-III criteria who had not responded to double-blind treatment with carbamazepine were treated with the blind addition of lithium to carbamazepine. Eight patients (53%) responded with a moderate to marked improvement. The time to onset of substantial clinical improvement was rapid; ie, the mean (+/- SD) was 4.1 +/- 2.4 days for lithium potentiation compared with 9.7 +/- 4.1 days in a separate group of depressed patients responding to lithium alone. Side effects during carbamazepine-lithium combination therapy were minimal. The mechanisms by which lithium appears to rapidly potentiate the effects of carbamazepine in treatment-resistant depression are discussed.