As any smoker can tell you, nicotine is a remarkably addictive drug; only about seven percent of people who try to quit smoking on their own last at least one year. Nicotine is among the most heavily used addictive drugs in the country, in spite of the long-known facts regarding smoking's potential to cause lung cancer and many other health problems.
Nicotine is one of the most heavily used addictive drugs in the U.S., and the leading preventable cause of disease, disability, and death. Cigarette smoking accounts for 90 percent of lung cancer cases in the U.S., and about 38,000 deaths per year can be attributed to secondhand smoke. Most cigarettes in the U.S. market today contain 10 milligrams (mg) or more of nicotine. The average smoker takes in 1 to 2 mg nicotine per cigarette when inhaling
In 1989, the Surgeon General issued a report indicating that cigarettes and other forms of tobacco which contain nicotine (such as cigars, pipe tobacco, and chewing tobacco) are addictive. The report also determined that smoking was a major cause of stroke as well as the third leading cause of death in the U.S.
What Is Nicotine?
Nicotine is one of more than 4,000 chemicals found in the smoke from tobacco products;it is the primary component that acts on the brain. Smokeless tobacco products (for example, snuff and chewing tobacco) also contain many toxins as well as high levels of nicotine. Nicotine is a naturally occurring, colorless liquid that turns brown when burned and takes on the odor of tobacco when exposed to air. There are many species of tobacco plants, the tabacum species serving as the major source of today's tobacco products. Extensive study shows it to have a number of complex and sometimes unpredictable effects on the brain and body.
Nicotine is absorbed through the skin and mucosal lining of the nose and mouth or in the lungs (through inhalation). Nicotine can reach peak levels in the bloodstream and brain rapidly, depending on how it is taken. Cigarette smoking results in nicotine reaching the brain within just 10 seconds of inhalation. Cigar and pipe smokers, on the other hand, typically do not inhale the smoke, so nicotine is absorbed more slowly through the mucosal membranes of their mouths (as is nicotine from smokeless tobacco).
Nicotine is addictive, which is why most smokers tend to do it regularly. Addiction is characterized by compulsive drug seeking and use, even at the risk of negative health consequences. Most smokers know that tobacco is harmful and express a desire to decrease or end use of it, with nearly 35 million people seriously attempting to quit each year. Unfortunately, most relapse within just a few days, and less than seven percent of those who try to quit on their own achieve about a year of abstinence.
Besides nicotine's addictive properties, other factors to consider include its easy availability, the small number of legal and social consequences of tobacco use and the sophisticated marketing and advertising methods of tobacco companies. These combined with nicotine's addictive properties often lead to first use and, ultimately, addiction.
Recent research has shown how nicotine acts on the brain. Nicotine activates the circuitry that regulates feelings of pleasure, the so-called reward pathways. Research has shown that nicotine increases the levels of dopamine (a key brain chemical involved in mediating the desire to consume drugs) in the reward circuits of the brain. Nicotine's pharmacokinetic properties have been found to enhance its abuse potential. Smoking cigarettes produces a rapid distribution of nicotine to the brain, with drug levels peaking within 10 seconds of inhalation. The acute effects of nicotine dissipate within a few minutes, causing the need to continue repeated intake throughout the day.
A cigarette is a very efficient and highly engineered drug-delivery system. A smoker can get nicotine to the brain very rapidly with every inhalation. A typical smoker will take 10 puffs on a lit cigarette over a period of five minutes. Thus, a person who smokes about one-and-a-half packs (30 cigarettes) each day gets 300 nicotine hits to the brain daily. These factors contribute considerably to nicotine's highly addictive nature.
Using advanced neuroimaging technology, research is beginning to show that nicotine may not be the only psychoactive ingredient in tobacco. Scientists can see the dramatic effect of cigarette smoking on the brain and are finding a marked decrease in the levels of monoamineoxidase (MAO), an enzyme responsible for breaking down dopamine. The change in MAO must be caused by some tobacco smoke ingredient other than nicotine, since nicotine itself does not dramatically alter MAO levels. The decrease in two forms of MAO, A and B, results in higher dopamine levels. The need to sustain the high dopamine levels results in the desire for repeated drug use.