Harvard Mental Health Letter

Breaking free from nicotine dependence

More than 46 million adults in the United States smoke cigarettes, cigars, or pipes, and a few million use snuff or chewing tobacco. Although 70% of smokers say they'd like to stop, nicotine is so addictive that only 3% successfully quit each year. Smoking sends nicotine straight to the lungs, where it is absorbed by oxygenated blood, delivered to the heart, and pumped into the arteries and to the brain. The nicotine in snuff and chewing tobacco, which is absorbed mainly through the mucous membranes of the mouth, reaches the brain more slowly, but constant use maintains a steady level in the blood and brain. Once in the brain, nicotine triggers the release of the neurotransmitter dopamine in the nucleus accumbens, which is the brain's reward and motivation center. Each hit of nicotine produces pleasurable feelings. But as it gets washed out of the body, the feelings of pleasure are replaced by uncomfortable symptoms of withdrawal — trouble concentrating, nervousness, headaches, increased appetite, dizziness, irritability, anxiety, depression, and sleeping problems. This prompts most users to reach for more tobacco. For people who want to stop using tobacco, two hurdles must be jumped: overcoming the physical addiction to nicotine and breaking the psychological habit.
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