Tuesday, March 9, 2010

Two popular hypotheses have been used to explain the addictive nature of nicotine in cigarette smokers: 1) a rapid brain nicotine accumulation during smoking and/or 2) puff-associated spikes in brain nicotine concentration.  Researchers from Duke University Medical Center and Wake Forest University School of Medicine set out to address these hypotheses by investigating the dynamics of nicotine accumulation in a smoker’s brain during actual cigarette smoking using positron emission tomography (PET) with 3-s temporal resolution and C-nicotine loaded cigarettes.  Published online yesterday in the Early Edition of Proceedings of the National Academy of Sciences, the results of the study suggest that puff-associated spikes in brain nicotine concentration do not and could not exist during habitual cigarette smoking.  Brain nicotine concentration steadily increases during smoking, producing one spike in brain nicotine associated with smoking of an entire cigarette.  Furthermore, dependent smokers have a slower process of brain nicotine accumulation than nondependent smokers because they have slower nicotine washout from the lungs.  For this reason, researcher said, more rapid brain nicotine accumulation alone is not sufficient to maintain a dependency on cigarette smoking.

Researchers noted that even without discrete puff-associated spikes, the rapid brain accumulation of nicotine (which starts about seven seconds after inhalation), may be a factor leading to the relatively high addictiveness of cigarettes when compared to other forms of nicotine administration such as nicotine patches and gum.  Because understanding the mechanisms that underlie nicotine dependence in cigarette smokers is crucial to developing improved strategies to help with smoking cessation, it is important that further research is done to unveil the specific role of the rate of brain nicotine accumulation in controlling smoking behavior.

Brandi Robinson
Program Associate, Partnership for Prevention


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