Nicotine is the addictive chemical in tobacco, which has been used as a mood-altering substance for centuries. Overcoming nicotine addiction can be very difficult, due to the involvement of several biobehavioral processes of drug dependence, including reinforcement and withdrawal. The 1988 Surgeon General's report concluded that, "Pharmacologic and behavioral characteristics that determine tobacco addiction are similar to those that determine addiction to drugs such as heroin and cocaine." Unfortunately, the strength of tobacco addiction is underestimated by many children and adolescents, and the Surgeon General reports that nicotine addiction kills more than 300,000 Americans a year.
Reinforcement
Nicotine is a central nervous system stimulant. Once in the bloodstream, it is distributed rapidly throughout the body and enters the brain, where it interacts with receptor cells and initiates metabolic and electrical activity. Increased adrenaline production in the body constricts peripheral blood flow, making the heart beat faster and work harder, raising blood pressure and pulse. Nicotine's effect on the overall metabolic rate, the regulation of body temperature, the relaxation of skeletal muscles and fluctuation of hormones creates a pleasant euphoric sensation. Reinforcement occurs when the pharmacological activity of a drug is sufficiently rewarding to maintain self-administration. Behavior becomes compulsive and is controlled by the psychoactive effect of nicotine. Stereotypical patterns of use develop despite harmful effects.
Tolerance
The body rapidly builds tolerance to the effects of nicotine. Doses needed to achieve the desired effect rise immediately, encouraging use of greater and greater amounts. Once addicted, the body depends on having adequate amounts of nicotine, and symptoms of withdrawal begin to occur as soon as these amounts decrease or stop. Irritability, anxiety, depression, sleep disturbances and intense recurrent drug cravings ensure that relapse follows efforts to abstain and that self-administration of nicotine persists, despite a desire to quit.
Psychological Dependency
Long-term cravings continue after physical withdrawal ends. This may be because the use of nicotine becomes associated with pleasure and certain daily activities. Users may believe that nicotine aids mental performance, helps them cope with life's difficult moments and allows them to stay thin. Psychological enhancement and sensory gratification are effects of addiction that initiate, maintain and cause the relapse of habitual nicotine use. The Surgeon General, in the 1988 report on nicotine addiction, reviewed studies that tested these beliefs and concluded that smokers are more alert after smoking but that nicotine does not enhance learning, that stress is a risk factor associated with nicotine use, and that smokers weigh an average of seven pounds less than nonsmokers. Weight gain should be addressed as part of any nicotine cessation program.
