Tobacco

Nicotine Effects

Nicotine is the main psychoactive and addictive component of cigarettes and other tobacco products. When tobacco is smoked, nicotine is absorbed through the alveoli in the lungs, and when it is chewed or used as a snuff, it is absorbed through the mucosal membranes into the bloodstream. Nicotine has direct effects on nicotinic acetylcholine receptors, but also activates dopamine in the mesolimbic (“rewards center”) of the brain, although to a lesser extent than some drugs such as cocaine. Although nicotine can cause some improvement in domains such as attention, memory, and motor ability in nonsmokers, much of the improvement in such domains in smokers are the result of alleviation of nicotine withdrawal symptoms rather than a substantial net benefit of nicotine. Nicotine has been shown to increase the reinforcing value of other stimuli in the environment during the course [Page 777]of drug action. This is consistent with the observation that smokers usually do not experience the euphoria associated with many addictive drugs, but sometimes report that smoking increases enjoyment of other pleasurable activities such as social interaction. The effects of smoking are often found to be aversive to the novice smoker, and therefore social reinforcement (peer pressure, approval of friends) likely is critical to the initial establishment of nicotine addiction.

Prevalence, Mortality, and Other Harms

Worldwide, approximately 1 billion men and 250 million women are daily smokers. In the United States, 23 percent of adults are current smokers. Among high school seniors, over 44 percent have smoked at least once in their lifetime, and 20 percent are current smokers. Over 400,000 people in the United States and 5 million people worldwide die of cigarette smoking-related diseases every year, far exceeding the number of deaths associated with alcohol use or illegal drug use.

Evidence that smoking was related to diseases such as lung cancer became recognized and appreciated in the United States in the 1950s. Since then, increasing evidence has accumulated to demonstrate that smoking causes tremendous toxicity across a wide variety of health domains. The 1964 U.S. Surgeon General's report was a landmark recognition of the harms caused by smoking.

...