metabolism were more likely to be current versus former smokers at age 18 compared to normal metabolizers. Rubinstein et al. (2013) assessed a biomarker of the rate of nicotine metabolism (the nicotine metabolite ratio) in 164 adolescent smokers and found that slower metabolizers showed greater symptoms of dependence. Our findings in two independent samples expand on these earlier results by demonstrating that during early young adulthood, when many advanced smoking behaviors develop, slow metabolizers who smoke daily continue to have a greater risk of lifetime dependence.
