Addiction is characterized by compulsive drug-seeking and use, even in the face of negative health consequences. It is well documented that most smokers identify tobacco as harmful and express a desire to reduce or stop using it. Unfortunately, less than seven percent of those who try to quit on their own achieve more than one year of abstinence; most relapse within a few days of attempting to quit.
Recent research has shown in fine detail how nicotine acts on the brain to produce a number of behavioral effects. Nicotine activates the brain circuitry that regulates feelings of pleasure, the so-called reward pathways. Dopamine is an essential brain chemical involved in mediating an individual’s desire to consume drugs. Chemical properties of nicotine have been found to enhance its abuse potential. Cigarette smoking produces a rapid distribution of nicotine to the brain, with drug levels peaking within ten seconds of inhalation. The immediate effects of nicotine dissipate in a few minutes, causing the smoker to continue dosing frequently throughout the day to maintain the drug’s pleasurable effects and prevent withdrawal.
What people frequently do not realize is that the cigarette is a very efficient and highly engineered drug-delivery system. By inhaling, the smoker can get nicotine to the brain very rapidly with every puff. A typical smoker will take ten puffs on a cigarette over a period of five minutes that the cigarette is lit. Thus, a person who smokes about 1 1/2 packs (30 cigarettes) daily, gets 300 “hits” of nicotine to the brain each day. These factors contribute considerably to nicotine’s highly addictive nature.
Nicotine can act as both a stimulant and a sedative. Immediately after exposure to nicotine, there is a “kick” caused in part by the drug’s stimulation of the adrenal glands and resulting discharge of epinephrine (adrenaline). The rush of adrenaline stimulates the body and causes a sudden release of glucose as well as an increase in blood pressure, respiration, and heart rate. This reaction is similar to that seen with other drugs of abuse-such as cocaine and heroin. In contrast, nicotine can also exert a sedative effect, depending on the level of the smoker’s nervous system arousal and the dose of nicotine taken.
Repeated exposure to nicotine results in the development of tolerance, the condition in which higher doses of a drug are required to produce the same initial stimulation. Nicotine is metabolized fairly rapidly, disappearing from the body in a few hours. Therefore some tolerance is lost overnight, and smokers often report that the first cigarettes of the day are the strongest and/or the “best.”
A withdrawal syndrome that may last a month or more follows cessation of nicotine use. Symptoms peak within the first few days and may subside within a few weeks. For some people, however, symptoms may persist for months or longer. These symptoms can quickly drive people back to tobacco use.
An important but poorly understood component of the nicotine withdrawal syndrome is craving, an urge for nicotine that has been described as a major obstacle to successful abstinence. High levels of craving for tobacco may persist for six months or longer. While the withdrawal syndrome is related to the chemical effects of nicotine, many behavioral factors also can affect the severity of withdrawal symptoms. For some people, the feel, smell, and sight of a cigarette and the ritual of obtaining, handling, lighting, and smoking the cigarette are all associated with the pleasurable effects of smoking and can make withdrawal or craving worse. While nicotine gum and patches may alleviate the chemical aspects of withdrawal, cravings often persist. For more information visit http://www.nida.nih.gov/ResearchReports/Nicotine/Nicotine.html
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