Nicotine is one of the most heavily used addictive drugs in the United States. The U.S. Surgeon General's office even issued a report that concluded that cigarettes and other forms of tobacco, such as cigars, pipe tobacco, and chewing tobacco, are addictive and that nicotine is the drug in tobacco that causes addiction. In addition, the report determined that smoking was a major cause of stroke and the third leading cause of death in the United States.
Highly Addictive
Nicotine is highly addictive. It is both a stimulant and a sedative to the central nervous system. The ingestion of nicotine results in an almost immediate "kick" because it causes a discharge of epinephrine from the adrenal cortex. This stimulates the central nervous system, and other endocrine glands, which causes a sudden release of glucose. Stimulation is then followed by depression and fatigue, leading the abuser to seek more nicotine. Nicotine is absorbed readily from tobacco smoke in the lungs, and it doesn't matter if the tobacco smoke is from cigarettes, cigars, or pipes.
Nicotine also is absorbed readily when tobacco is chewed. With regular use of tobacco, levels of nicotine accumulate in the body during the day and persist overnight. Thus, daily smokers or chewers are exposed to the effects of nicotine for 24 hours each day. Nicotine taken in by cigarette or cigar smoking takes only seconds to reach the brain, but it has a direct effect on the body for up to 30 minutes.
Research has shown that stress and anxiety affect nicotine tolerance and dependence. The stress hormone corticosterone reduces the effects of nicotine. Therefore, more nicotine must be consumed to achieve the same effect. This increases tolerance to nicotine and leads to increased dependence. Studies in animals have also shown that stress can directly cause relapse to nicotine use after a period of abstinence.
Other studies have shown that animals cannot discriminate between the effects of nicotine and the effects of cocaine. Studies have also shown that nicotine use sensitizes animals to self-administer cocaine more readily.
Addiction to nicotine results in withdrawal symptoms when a person tries to stop smoking. For example, a study found that when chronic smokers were deprived of cigarettes for 24 hours, they had increased anger, hostility, and aggression, and loss of social cooperation. People suffering from withdrawal also take longer to regain emotional equilibrium following stress. During periods of abstinence and/or craving, smokers have shown impairment across a wide range of psychomotor and cognitive functions – even including language comprehension!
Other Hazards
Women who smoke generally have earlier menopause. If women smoke cigarettes and also take oral contraceptives, they are more prone to cardiovascular and cerebrovascular diseases than are other smokers. This is especially true for women older than 30.
Pregnant women who smoke cigarettes 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. National studies of mothers and daughters have also found that maternal smoking during pregnancy increased the probability that female children would smoke and would persist in smoking.
Adolescent smokeless tobacco users are more likely than nonusers to become cigarette smokers. Behavioral research is beginning to explain how social influences, such as observing adults or other peers smoking, cause adolescents to start smoking cigarettes. Research has shown that teens are generally resistant to many kinds of anti-smoking messages.
Current smokers are more likely to drink heavily and use illicit drugs than are non-smokers.
In addition to nicotine, cigarette smoke is primarily composed of a dozen gases (mainly carbon monoxide) and tar. The tar in a cigarette, which varies from about 15 mg for a regular cigarette to 7 mg in a low-tar cigarette, exposes the user to a high expectancy rate of lung cancer, emphysema, and bronchial disorders. The carbon monoxide in the smoke increases the chance of cardiovascular diseases.
The Environmental Protection Agency concludes that secondhand smoke causes lung cancer in adults and greatly increases the risk of sudden infant death as well as respiratory illnesses in children.
Promising Research
Research has shown that nicotine, like cocaine, heroin, and marijuana, increases the level of the neurotransmitter dopamine, which affects the brain pathways that control reward and pleasure. Scientists have now pinpointed a particular molecule (the beta 2 subunit of the nicotine cholinergic receptor) as a critical component in nicotine addiction. Mice that lack this molecule fail to self-administer nicotine, implying that without the b2 molecule, the mice do not experience the positive reinforcing properties of nicotine. This new finding identifies a potential site for targeting the development of anti-nicotine addiction medications.
Treatment
Research suggests that smoking cessation should be a gradual process because withdrawal symptoms are less severe in those who quit gradually than in those who quit all at once. Rates of relapse are highest in the first few weeks and months and diminish considerably after three months.
Studies have shown that drug treatment combined with psychological treatment, including psychological support and skills training to overcome high-risk situations, result in some of the highest long-term abstinence rates.
Additional studies find that alternative rewards and reinforcers can reduce cigarette use. One study even found that the greatest reductions in cigarette use were achieved when the cost of cigarettes was increased then combined with the presence of alternative recreational activities.
Nicotine chewing gum is one medication approved by the Food and Drug Administration (FDA) for the treatment of nicotine dependence. Nicotine in this form acts as a nicotine replacement to help smokers quit the smoking habit.
The success rates for smoking cessation treatment with nicotine chewing gum vary considerably across studies. But evidence suggests that it's a safe way of helping smokers quit the habit – if the gum is chewed according to instructions and if it's restricted to patients who are under medical supervision.
A Vaccine for Nicotine Addiction?
Another approach to smoking cessation is the nicotine transdermal patch, a skin patch that delivers a relatively constant amount of nicotine to the person wearing it. A research team at National Institute on Drug Abuse's Division of Intramural Research looked at the safety, mechanism of action, and abuse potential of the patch that was consequently approved by FDA. Both nicotine gum and the nicotine patch, plus spray and inhaler nicotine replacements – are used to help people fully quit smoking by reducing their withdrawal symptoms and by preventing relapse while they undergo behavioral treatment.
Another tool in treating nicotine addiction is the medication Zyban. This is not a nicotine replacement. Rather, it works on other areas of the brain, and is effective in helping people who are trying to quit , to control their nicotine cravings or thoughts about cigarette use.
In the meantime, scientists have been developing a nicotine vaccine. When it was tested on animals, scientists found that the amount of nicotine reaching the brain was reduced by 64 percent. Clinical trials are now underway. It's hoped that the vaccine will prevent nicotine from reaching the brain. This could potentially help addicted people quit and keep people from ever becoming addicted. |
