Mechanisms of Weight Gain in Major Depressive Disorder Patients Taking Serotonin Reuptake Inhibitors

Abstract

<p>Individuals with mood disorders are particularly vulnerable to weight gain, due in part to an illness symptom profile that impacts appetite and energy and the iatrogenic weight-gain effects associated with psychotropic medications. The exact physiological mechanisms through which medication causes weight gain have yet to be clearly elucidated. The studies comprising this thesis examine changes in caloric consumption, physical activity and basal metabolic rate (BMR) in depressive disorder (MDD) patients starting on selective serotonin reuptake inhibitors (SSRIs). Since both depression and obesity have been linked to inflammation, we also monitored changes in cytokines and adipokines throughout treatment. In our sample, we observed a mean weight gain from baseline, prior to medication, to 6 months after the initiation of pharmacotherapy. We note that this weight gain is not likely due to increased caloric consumption, but could be related to the proportions of macronutrients being consumed and expended, as well as physical activity level. We also observed changes in adipokines and cytokines that are reflective of pharmacotherapy and not weight gain, even in the absence of clinical improvement. Collectively these studies have begun to shed light on the mechanisms involved in the weight gain experienced by MDD patients being treated with SSRI antidepressants. A better understanding of these mechanisms will lead to better management of the adverse metabolic side effects associated with psychotropic medication, and will improve patient compliance.</p>