WEDNESDAY, May 4 (HealthDay News) -- Secondhand smoke could trigger cravings for nicotine and make it harder for smokers to kick the habit, a new study suggests.

The research, funded by the U.S. National Institute on Drug Abuse (NIDA), found that secondhand smoke has a direct and measurable impact on the brain similar to that of actually smoking.

Scientists used positron emission tomography (PET) scans to show that just one hour of exposure to secondhand smoke in an enclosed area allows nicotine to reach the brain and bind to receptors normally targeted by direct exposure to tobacco smoke.

"These results show that even limited secondhand smoke exposure delivers enough nicotine to the brain to alter its function," Dr. Nora D. Volkow, NIDA director, said in a news release. "Chronic or severe exposure could result in even higher brain nicotine levels, which may explain why secondhand smoke exposure increases vulnerability to nicotine addiction."

The findings underscore previous research, which suggests that exposure to secondhand smoke increases a child's chances of becoming a smoker later in life.

"This study gives concrete evidence to support policies that ban smoking in public places, particularly enclosed spaces and around children," Dr. Arthur Brody, of the department of psychiatry & biobehavioral sciences at the University of California, Los Angeles, said in the NIDA news release.

Secondhand smoke claims nearly 50,000 lives each year in the United States, according to the U.S. Centers for Disease Control and Prevention. In 2006, the U.S. Surgeon General concluded that secondhand smoke is responsible for a number of serious health problems among nonsmoking adults and children, including:

• heart disease
• lung cancer
• sudden infant death syndrome (SIDS)
• respiratory infections
• severe asthma

The research was published in the May 2 issue of the Archives of General Psychiatry.

More information

The American Cancer Society offers a detailed guide on how to quit smoking.