About 62 million people in the United States ages 12 and older, or 29 percent of the population, are current cigarette smokers, according to the 1996 National Household Survey on Drug Abuse. This makes nicotine, the addictive component of tobacco, one of the most heavily used addictive drugs in the United States.
Effects of Nicotine
When a person inhales cigarette smoke, the nicotine in the smoke is rapidly absorbed into the blood and starts affecting the brain within 7 seconds. In the brain, nicotine activates the same reward system as do other drugs of abuse such as cocaine or amphetamine, although to a lesser degree. Nicotine's action on this reward system is believed to be responsible for drug-induced feelings of pleasure and, over time, addiction. Nicotine also has the effect of increasing alertness and enhancing mental performance. In the cardiovascular system, nicotine increases heart rate and blood pressure and restricts blood flow to the heart muscle. The drug stimulates the release of the hormone epinephrine, which further stimulates the nervous system and is responsible for part of the "kick" from nicotine. It also promotes the release of the hormone beta-endorphin, which inhibits pain.
People addicted to nicotine experience withdrawal when they stop smoking. This withdrawal involves symptoms such as anger, anxiety, depressed mood, difficulty concentrating, increased appetite, and craving for nicotine. Most of these symptoms subside within 3 to 4 weeks, except for the craving and hunger, which may persist for months.
Health Effects of Tobacco Products
Besides nicotine, cigarette smoke contains more than 4,000 substances, many of which may cause cancer or damage the lungs. Cigarette smoking is associated with coronary heart disease, stroke, ulcers, and an increased incidence of respiratory infections. Smoking is the major cause of lung cancer and is also associated with cancers of the larynx, esophagus, bladder, kidney, pancreas, stomach, and uterine cervix. Smoking is also the major cause of chronic bronchitis and emphysema.
Women who smoke cigarettes have earlier menopause. Pregnant women who smoke run an increased risk of having stillborn or premature infants or infants with low birthweight. Children of women who smoked while pregnant have an increased risk for developing conduct disorders.
Cigar and pipe smokers and users of chewing tobacco and snuff can also become addicted to nicotine. Although cigar and pipe smokers have lower death rates than cigarette smokers do, they are still susceptible to cancers of the oral cavity, larynx, and esophagus. Users of chewing tobacco and snuff have an elevated risk for oral cancer.
Like addiction to heroin or cocaine, addiction to nicotine is a chronic, relapsing disorder. A cigarette smoker may require several attempts over many years before that person is able to permanently give up smoking. Less than 10 percent of unaided quit attempts lead to successful long-term abstinence. However, studies have shown significantly greater cessation rates for smokers receiving interventions compared to control groups who do not receive the interventions. Interventions that involve both medications and behavioral treatments appear to show the most promise.
The primary medication therapy currently used to treat nicotine addiction is nicotine replacement therapy, which supplies enough nicotine to
the body to prevent withdrawal symptoms but not enough to provide the quick jolt caused by inhaling a cigarette. Four types of nicotine replacement products are currently available. Nicotine gum and nicotine skin patches are available over the counter. Nicotine nasal spray and nicotine inhalers are available by prescription. On average, all types of nicotine replacement products are about equally effective, roughly doubling the chances of successfully quitting.
Another medication recently approved by the Food and Drug Administration is the antidepressant bupropion, or Zyban. The association between nicotine addiction and depression is not yet understood, but nicotine appears to have an antidepressant effect in some smokers. Paradoxically, though, buproprion is more effective for treating nicotine addiction in nondepressed smokers than in smokers who are depressed.