Also, insulin plays a role in energy metabolism and other aspects of central nervous system function,27 and insulin abnormalities may exacerbate cognitive impairment.28 In fact, increased peripheral insulin results in insulin resistance, which itself has substantial outcomes on the brain29 and has been associated with depression.30,31,32 Furthermore, persons with, for example, ADHD and mood disorders have been reported to have an increased risk of developing obesity. This evidence concerns the gene INS and major depressive disorder.