May 2, 2011 -- Secondhand smoke may trigger nicotine cravings and make it harder for cigarette smokers to quit.
A new study shows secondhand smoke exposure delivers a "priming" dose of nicotine to the brain that increases nicotine craving in smokers.
"This mechanism may explain why adult smokers exposed to multiple sources of SHS [secondhand smoke] have difficulty initiating and maintaining abstinence compared with smokers without such exposure," write researcher Arthur Brody and colleagues in the Archives of General Psychiatry.
In the study, researchers examined the effects of secondhand smoke exposure in 24 young adults, including 11 cigarette smokers and 13 nonsmokers.
The participants underwent PET scanning as they sat in the passenger seat of a car for one hour while being exposed to moderate amounts of secondhand smoke or no smoke at all.
Increased Nicotine Cravings
The results showed that exposure to secondhand smoke led to an increase in plasma nicotine concentration of about 0.2 ng/mL and a 19% increase in nicotine receptor occupancy in the brain.
In addition, smokers had an average 23% increase in nicotine cravings with exposure to secondhand smoke, which were alleviated by subsequent cigarette smoking.
"Study findings suggest that such exposure delivers a priming dose of nicotine to the brain that contributes to continued cigarette use in smokers," write the researchers.
Researchers say several health care groups have called for wider smoking bans in cars, and the results of this study strongly support those recommendations.