Regarding the PANSS depressive subscale items (Table 3 and Table 4), platelet MAO-B activity was significantly lower in smokers and non-smokers with severe G2 (anxiety) and G6 (depression) symptoms when compared with those with mild symptoms, but was similar in those with severe or mild G1 (somatic concern) and G3 (guilty feelings) symptoms. This evidence concerns the gene MAOB and major depressive disorder.