CYP2A6 and nicotine dependence: In several investigations, smokers with CYP2A6 reduce-of-function genotypes or slower CYP2A6 activity (lower NMR quartiles) exhibited lower FTND (Fagerström Test for Nicotine Dependence) scores, a measure of the degree of nicotine dependence, compared to faster nicotine metabolizers [109,110,111].