A recent small study [40] found significantly lower plasma levels of adiponectin and significantly higher levels of the leptin/adiponectin (L/A) ratio in the ADHD group (n = 36) compared with healthy controls (n = 40), suggesting that a low adiponectin level and high L/A may underlie the link ADHD–obesity. Here, ADIPOQ is linked to obesity due to melanocortin 4 receptor deficiency.