Low-nicotine doesn't mean less nicotine

Low-nicotine cigarettes are used by some smokers as a first step to wean themselves from their addiction. A study from UCLA researchers, however, casts doubt on that strategy.

Light cigarettes contain from 0.6 to 1 milligram of nicotine compared with 1.2 to 1.4 milligrams in regular cigarettes. But light cigarettes deliver nearly as much of a nicotine punch to the brain as regular cigarettes, the study found. Even the smaller amount of nicotine in the light cigarettes is enough to bind to a significant percentage of the brain's nicotine receptors. Engaging the brain's nicotine receptors leads to a rush of the brain chemical dopamine and gives smokers a pleasurable feeling.

The study also looked at de-nicotinized cigarettes and their effects on the brain. These cigarettes contain only a trace of nicotine (.05 mg) and are being studied as a tool to help smokers quit. But even these cigarettes release enough nicotine to engage a sizable number of the brain's nicotine receptors. A previous study showed that a regular cigarette occupied 88% of the brain's nicotine receptors. This study found that a light cigarette occupied 79% of the receptors and a de-nicotinized cigarette 26%.

"Very little nicotine is needed to occupy a substantial portion of the brain nicotine receptors," said Dr. Arthur L. Brody, a UCLA psychiatry professor. "Researchers, clinicians and smokers themselves should consider that fact when trying to quit."

The study was performed on 15 smokers. They were examined with positron emission tomography scans of their brains after smoking a regular cigarette, a light cigarette and a de-nicotinized cigarette. The study was published online Friday in the International Journal of Neuropsychopharmacology.

The National Cancer Institute says that smoking light cigarettes does not reduce the health risks from smoking. For more information on the health impact from smoking light cigarettes, see this NCI fact sheet.

-- Shari Roan

Photo credit: European Pressphoto Agency

Comments

[John R. Polito]

Interesting. Clearly the nicotine levels given are not the amount contained within each cigarette but the amount delivered into the bloodstream. We're told that over time tolerance causes the smokers brain to up-regulate or grow/activate millions of additional a4b2 type acetylcholine receptors and that nicotine cessation down-regulates receptor counts within 3 weeks, in at least 11 different brain regions. We've also learned that just 1 to 2 puffs of nicotine is sufficient to occupy up to 50% of receptors. While moving closer to an understanding of the dynamics of nicotine's impact upon receptors we also need focus upon their influence. What is the minimum percentage of receptors that need to be occupied and for how long in order to: (1) induce dependency onset (2) maintain chemical dependency and (3) foster relapse?