Revised August 2008
Tobacco use is the leading preventable cause of disease, disability, and death in the United States. Cigarette smoking results in more than 400,000 preventable deaths each year – about one in every five U.S. deaths. Despite the well-documented health costs of smoking, many smokers have great difficulty quitting, and many others are still becoming addicted – about 1200 per day in the U.S. Researchers are striving to understand the numerous effects of nicotine on the brain and body, determine why it is so addictive, and help smokers break its hold for good.
Research has shown that nicotine influences the same brain regions as other drugs of abuse, the so-called "reward system." Like cocaine, heroin, and marijuana, nicotine increases levels of the neurotransmitter dopamine in the reward system, producing lasting changes in the cells of the brain. These changes can eventually lead to addiction. Current priorities at NIDA include:
Why do some smokers become addicted, while others don't? Studies indicate that as much as half of a smoker's risk of becoming addicted depends on his or her genes. Recent technical advances have enabled researchers to conduct large-scale studies of the complex genetic contribution to addiction. For example, a recent NIDA-supported study found that having a certain variant in the gene for a nicotinic receptor subunit more than doubled the risk for addiction among smokers, as well as increasing their vulnerability to lung cancer and peripheral arterial disease.
While genetic studies reveal exciting new directions for research, environmental risk factors are equally important. NIDA supports targeted research on factors correlated with tobacco use and addiction, including prenatal exposure to tobacco smoke; social environments; gender; ethnicity; age; comorbid conditions like depression and schizophrenia; and exposure to other drugs of abuse.
According to NIDA's 2007 Monitoring the Future survey, 21.6 percent of 12th graders reported using cigarettes in the past month. Of those adolescents who try smoking, about one out of three will become regular smokers. Research shows that adolescents are especially vulnerable to nicotine addiction; the prefrontal cortex does not fully mature until the twenties, so the adolescent brain may be less able to override impulsive decisions or cravings for drugs. In addition, acetaldehyde, a compound found in tobacco smoke, may enhance nicotine's addictive effects, especially in adolescents. NIDA directs significant resources toward monitoring teen tobacco use, understanding the biology behind it, and developing prevention programs targeted at teens.
In addition to increasing risk for miscarriage, stillborn or premature infants, and low birth weight, maternal smoking predisposes children to a host of long-term behavioral problems, some of which only become apparent later in life. Children whose mothers smoke during pregnancy are also more likely to become dependent on tobacco if they start smoking. Understanding the persistent, deleterious effects of nicotine on the developing fetal brain is a priority for NIDA.
70% of current adult smokers in the US would like to quit, but most have difficulty overcoming their addiction and managing withdrawal symptoms and cravings. NIDA is translating knowledge gained from basic research into more effective treatments and medications to help smokers quit.
NIDA's 2007 Monitoring the Future survey indicates that teen smoking has reached its lowest level since the survey began in 1975. This bodes well for the future, but too many teens continue to smoke – 22 percent of 8th graders report having tried cigarettes. New prevention strategies are urgently needed, as are treatments to help teens and adults who are already addicted. Through science, NIDA is meeting these challenges, and reducing the national health burden created by tobacco and nicotine addiction.