Research is underway to investigate the effects of anti-TNF-alpha biologic infliximab on measures of anhedonia, motivational behavior, and glutamatergic changes in the basal ganglia71 and to investigate the effects of simvastatin for treatment-resistant MDD72 and patients with comorbid obesity and MMD73. This evidence concerns the gene TNF and obesity due to melanocortin 4 receptor deficiency.