There is a strong relationship between the hormone leptin and obesity especially in females [36]–[39]; however, leptin's role in cognition has been studied with mixed results [28]–[30] and there is a notable lack of published data on P300 utilization and its relationship with plasma leptin levels, despite studies indicating the association between leptin and cognitive genes. The gene discussed is LEP; the disease is obesity due to melanocortin 4 receptor deficiency.