Genetic nicotine metabolism has recently been seen to predict tendency to become a smoker.
In a new study conducted by the Montreal Neurological Institute and Hospital, The Neuro, McGill University, findings show people with a fast nicotine metabolism have a greater brain response to smoking signals than those with a slow nicotine metabolism. Earlier research establishes that greater reactivity to smoking signals anticipates decreased ability to quit smoking and environmental cues encourage greater nicotine intake in humans as well as animals.
As seen in other studies, tobacco use is still one of the leading causes of preventable death and disease in the United States. This new discovery that nicotine metabolism rates impact the brain’s response to smoking can potentially lead the way for customized smoking abstinence programs based on genetics.
Smoking prompts such as the sight of smoking, or a cigarette, are linked to cigarette use and relapse. Nicotine metabolism performed by a liver enzyme, can be fast or slow and affects the level of nicotine in the blood that travels to the brain. This particular study tested participants for their enzyme genotype and their nicotine metabolism rates.
Smokers aged 18 to 35 who consumed 5 to 25 cigarettes daily for at least two years were followed during the study. Brain response to smoking cues was examined by functional MRIs. Fast metabolizers had considerably higher responses to visual signals than slow metabolizers in areas of the brain associated with memory, motivation and reward.
Clinician-scientist Dr. Alain Dagher, lead investigator at The Neuro says,
“The finding that nicotine metabolism rate has an impact on the brain’s response to smoking cues supports our hypothesis that individuals with fast nicotine metabolism rates would have a greater brain response to smoking cues because of close coupling in everyday life between exposure to cigarettes and surges in blood nicotine concentration. In other words they learn to associate cigarette smoking with the nicotine surge.”
Slow metabolizers, on the other hand, have constant nicotine levels in the blood throughout the day and are less inclined to develop conditioned responses to signals. For these users, smoking is not linked with short nicotine surges, rather, it is used to maintain cognitive abilities such as attention span, memory, and stress relief. As seen in previous research, genetics play a role in the most successful way to treat smoking addiction.
Authors suggest future studies should focus on smoking abstinence programs designed for individuals. Measuring metabolism rates as a part of the decision making process for treatment may be effective. Patients with slow nicotine metabolism will most likely benefit from long-acting cholinergic drugs such as the nicotine patch, while those with fast nicotine metabolism will benefit from craving-induced therapy such as non-nicotine based buproprion, an anti depressant used to stop smoking.
Written by Kelly Fitzgerald