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Mind Over Matter
Nicotine Series
National Institute on Drug Abuse · National Institutes of Health
The Brain's Response to
Nicotine
For centuries, people have chewed and smoked tobacco, which comes from the plant nicotiana tabacum. The reason tobacco is used by so many people is because it contains a powerful drug known as nicotine.
When tobacco is smoked, nicotine is absorbed by the lungs and quickly moved into the bloodstream, where it is circulated throughout the brain. All of this happens very rapidly. In fact, nicotine reaches the brain within 8 seconds after someone inhales tobacco smoke. Nicotine can also enter the bloodstream through the mucous membranes that line the mouth (if tobacco is chewed) or nose (if snuff is used), and even through the skin.
Nicotine affects the entire body. Nicotine acts directly on the heart to change heart rate and blood pressure. It also acts on the nerves that control respiration to change breathing patterns. In high concentrations, nicotine is deadly, in fact one drop of purified nicotine on the tongue will kill a person. It's so lethal that it has been used as a pesticide for centuries.
So why do people smoke? Because nicotine acts in the brain where it can stimulate feelings of pleasure.
How Does Nicotine Act in the Brain?
Your brain is made up of billions of nerve cells. They communicate by releasing chemical messengers called neurotransmitters. Each neurotransmitter is like a key that fits into a special "lock," called a receptor, located on the surface of nerve cells. When a neurotransmitter finds its receptor, it activates the receptor's nerve cell.
The nicotine molecule is shaped like a neurotransmitter called acetylcholine. Acetylcholine and its receptors are involved in many functions, including muscle movement, breathing, heart rate, learning, and memory. They also cause the release of other neurotransmitters and hormones that affect your mood, appetite, memory, and more. When nicotine gets into the brain, it attaches to acetylcholine receptors and mimics the actions of acetylcholine.
Nicotine also activates areas of the brain that are involved in producing feelings of pleasure and reward. Recently, scientists discovered that nicotine raises the levels of a neurotransmitter called dopamine in the parts of the brain that produce feelings of pleasure and reward. Dopamine, which is sometimes called the pleasure molecule, is the same neurotransmitter that is involved in addictions to other drugs such as cocaine and heroin. Researchers now believe that this change in dopamine may play a key role in all addictions. This may help explain why it is so hard for people to stop smoking.
Easy to Start, Hard to Quit
Did you know that nicotine is as addictive as heroin or cocaine? If someone uses nicotine again and again, such as by smoking cigarettes or cigars or chewing tobacco, his or her body develops a tolerance for it. Eventually, a person can become addicted. Once a person becomes addicted, it is extremely difficult to quit. People who start smoking before the age of 21 have the hardest time quitting, and fewer than 1 in 10 people who try to quit smoking succeed.
When nicotine addicts stop smoking they may suffer from restlessness, hunger, depression, headaches, and other uncomfortable feelings. These are called "withdrawal symptoms" because they happen when nicotine is withdrawn from the body.
America's Leading Preventable Killer
Withdrawal may be bad, but long-term smoking can be much worse. It raises your blood pressure, dulls your senses of smell and taste, reduces your stamina, and wrinkles your skin. More dangerously, long-term smoking can lead to fatal heart attacks, strokes, emphysema, and cancer.
You may be surprised to learn that tobacco use causes far more illnesses and death than all other addicting drugs combined. One out every six deaths in the United States is a result of smoking.
But even when faced with risk of death, many people keep using tobacco because they are so addicted to nicotine. Believe it or not, half of the smokers who have heart attacks keep smoking, even though their doctor warns them to stop. That's a strong addiction!
Smokeless tobacco also has harmful effects. Chewing tobacco can cause damage to gum tissue and even loss of teeth. It also reduces a person's ability to taste and smell. Most importantly, smokeless tobacco contains cancer causing-chemicals that can cause cancers of the mouth, pharynx, larynx, and esophagus. This can even happen in very young users of chewing tobacco. In fact, most people who develop these cancers were users of chewing tobacco.
For printed copies of this publication contact:
National Clearinghouse for Alcohol and Drug Information
P.O. Box 2345
Rockville, MD 20847
1-800-729-6686Mind Over Matter is produced by the National Institute on Drug Abuse, National Institutes of Health. These materials are in the public domain and may be reproduced without permission. Citation of the source is appreciated. NIH Publication No. 98-4248.
Women and the Contemporary Lung Cancer Epidemic
An article by Dr. Peter Bach and Dr Mark Kris of Sloan Kettering Cancer Center in New York and Dr Jyoti Patel of Northwestern University report in the Journal of the American Medical Association that lung cancer has become “a contemporary epidemic” in women. Most cases, up to 80 percent in women, are from smoking. Last year, 80,100 new cases were diagnosed in American women, and 68,800 women died from the disease.
“Lung cancer is among the deadliest cancers because it often starts spreading long before being detected. Among cases diagnosed from 1992 to 1999, only 12 percent overall survived five years, 10 percent of the men and 14 percent of the women.
“The disease kills more women in the United States than any other cancer, as many as breast cancer and all gynecological cancers combined. Lung cancer bypassed breast cancer in 1987 as the leading cause of cancer deaths in women. From 1930 to 1997, as more and more women took up smoking, their death rate from lung cancer rose 600 percent.
“Although smoking has been known for decades to cause most lung cancers, a quarter of adult women in the United States smoke. In 2000, 30 percent of high school girls surveyed said they had smoked in the last 30 days. Since the 1950, smoking rates for American men have decreased nearly 50 percent. For women, the decrease is 25 percent…
“Multiple studies have found higher rates of genetic damage caused by tobacco in lung tumors in female than in male smokers, even though the women had, overall, smoked less. Women also appear less able to repair genetic damage.
“Compared with male smokers, women who smoke also have a more active version of a gene that makes chemicals in cigarette smoke more harmful to cells. Estrogen may make that gene more active...”
[This material was extracted from a report written by Denise Grady in the New York Times, published in the Seattle Post Intelligencer April 14, 2004.]
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