Imaging Study May Lead to More-Effective Smoking Cessation

Results of a new imaging study demonstrated that the nicotine received in just a few drags of a cigarette can exert a force powerful enough to drive an individual to continue smoking.

Researchers supported in part by the U.S. National Institute on Drug Abuse (NIDA; Rockville, MD, USA), U.S. National Institutes of Health (NIH), discovered that the amount of nicotine contained in just one puff of a cigarette can occupy about 30% of the brain's most common type of nicotine receptors, while three puffs of a cigarette can occupy about 70% of these receptors. When nearly all of the receptors are occupied (as a result of smoking at least two and one-half cigarettes), the smoker becomes satisfied, for a time. Soon, however, this level of satiation wears off, forcing the smoker to continue smoking throughout the day to satisfy cigarette cravings.

The study was published in the August 2006 issue of the journal Archives of General Psychiatry. The scientists, led by Dr. Arthur Brody of the David Geffen School of Medicine at the University of California, Los Angeles (UCLA; USA), utilized positron emission tomography (PET) to scan the brains of 11 smokers and assess nicotine distribution. During the scanning sessions, the participants smoked one of five amounts--none, one puff, three puffs, one full cigarette, or until their craving was satisfied (two and one-half to three cigarettes). Craving was measured with the Urge to Smoke scale, which evaluates responses to 10 craving-related questions. The scientists also performed magnetic resonance imaging (MRI) studies to help localize regions on the PET scans.

The investigators discovered that the highest levels of nicotine binding occurred in the thalamus (an area of the brain that acts as a conduit for all sensory data that reaches the brain's cerebral cortex, and which contains the highest concentration of these nicotine receptors), the brainstem (which controls various automatic functions, such as respiration, heart rate, and arousal), and the cerebellum (the area of the brain responsible for the coordination of movement and balance). Findings of another recently published NIDA-supported study suggest that a portion of the cerebellum called the vermis may be a major factor in modulating the brain's dopamine and reward systems, and may be more involved in drug abuse and addiction than previously thought.



Related Links:
National Institute on Drug Abuse
University of California, Los Angeles