Authors: Calabrese J, et al. Title: Effects of lithium and lamotrigine on body weight after 18 months in bipolar I disorder. Reference: European Neuropsychopharmacology, The Journal of the European College of Neuropsychopharmacology 2003;3(Suppl 4):S265. Purpose: To examine the effects of lithium and lamotrigine on body weight. Study design: Secondary analysis of two randomized, double-blinded trials. Follow up: 18 months. Patients: 638 patients (280 lamotrigine, 167 lithium). Treatment: Lamotrigine 50–400 mg/day, lithium 0.18–1.1 mEq. Results: Changes in patient body weight were significantly smaller in the lamotrigine-treatment group compared with patients in either the placebo- or lithium-treatment group. This difference was most evident in the obese category of patients, where on average, weight gain was +1.46 kg with placebo, +3.3 kg with lithium, and –2.96kg with lamotrigine.