The interaction between COMT and cannabis use (F = 3.556; P = 0.007; Eta Squared (η2)= 0.044) had a significant effect on the age of psychosis onset in a 2010 study by Pelayo-Terán (F = 3.816; P = 0.024; η2 = 0.045) [62]. This evidence concerns the gene COMT and psychotic disorder.