Comparison of brain nicotine accumulation after cigarette smoking in dependent and non-dependent smokers

Abstract

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Objectives: To evaluate the hypothesis that the accumulation of nicotine in the brain could be different in dependent (DS) and non-dependent smokers (NDS).

Methods: For this PET study we recruited 10 NDS and results were compared with those obtained from 13 DS (see Lokitz et al., this meeting). The head and chest of each participant were scanned for 10 minutes in two sessions after inhalation of a single puff from a Quest 1 research cigarette containing 370 MBq of [¹¹C]-nicotine.

Results: The maximal brain concentrations of [¹¹C]-nicotine observed in DS and NDS were 4.9 ± 0.6 and 5.9 ± 0.5 % of inhaled dose per kg of brain tissue, respectively. The time to reach 50% (T_1/2) of the maximum brain [¹¹C]-nicotine concentration in DS (33 ± 4 sec) was significantly higher (P < 0.01) than that in NDS (19 ± 3 sec). The washout of [¹¹C]-nicotine from the lungs in DS was significantly slower (P < 0.01) than in NDS with T_1/2 of 89 ± 18 sec and 27 ± 5 sec, respectively. A strong correlation between the T_1/2 for brain accumulation and T_1/2 for washout from the lungs was observed (r = 0.89, P < 0.0001).

Conclusions: Despite the intuitive expectation, we observed that DS have a slow accumulation of brain nicotine compared with NDS. This difference is driven by slower release of nicotine from the lungs in DS. Nonetheless, DS have a tendency to take bigger puff volumes, possibly to compensate for the difference in the rate of brain nicotine accumulation.

Research Support: Philip Morris USA