Our findings suggest that among adolescent smokers very early in their smoking career, those with faster metabolism have not yet begun to compensate for their increased nicotine clearance by increasing the number of cigarettes smoked per day, as has been observed among older addicted smokers. Furthermore, given that this group is clearing nicotine more quickly, it is likely that their brains are being exposed to smaller amounts of nicotine per cigarette compared to slower metabolizers. Conversely, the brains of slower metabolizers are exposed to greater amounts of nicotine for a longer period of time, and thus may be more likely to develop symptoms of addiction at this early stage of smoking. In other words, the slower inactivation and resultant increased levels of nicotine may increase susceptibility to dependence by increasing nicotine exposure and nicotine effects on the developing brain in teens.
