Through the use of cigarettes, cigars, and chewing tobacco, nicotine is
one of the most heavily used addictive drugs in the United States. In
2004, 29.2 percent of the U.S. population 12 and older—70.3 million
people—used tobacco at least once in the month prior to being
interviewed.* This figure includes 3.6 million young people age 12 to
17. Young adults aged 18 to 25 reported the highest rate of current use
of any tobacco products (44.6 percent) in 2004.
Findings for
high school youth indicate that 25.9 percent of 8th-graders, 38.9
percent of 10th-graders, and 50.0 percent of 12th-graders had ever
smoked cigarettes when asked in 2005.** These figures were lower for
all three grades from 2004 data, and for 8th-graders and 12th-graders,
the decreases were statistically significant.
Statistics from
the Centers for Disease Control and Prevention indicate that tobacco
use remains the leading preventable cause of death in the United
States, causing approximately 440,000 premature deaths each year and
resulting in an annual cost of more than $75 billion in direct medical
costs attributable to smoking. (See www.cdc.gov/tobacco/issue.htm.)
Over the past four decades, cigarette smoking has caused an estimated
12 million deaths, including 4.1 million deaths from cancer, 5.5
million deaths from cardiovascular diseases, 2.1 million deaths from
respiratory diseases, and 94,000 infant deaths related to mothers
smoking during pregnancy. (See www.cdc.gov/nccdphp/publications/aag/osh.htm.)
Secondhand
smoke, also known as environmental tobacco smoke, is a mixture of the
smoke given off by the burning end of tobacco products (sidestream
smoke) and the mainstream smoke exhaled by smokers. It is a complex
mixture containing many chemicals (including formaldehyde, cyanide,
carbon monoxide, ammonia, and nicotine), many of which are known
carcinogens. Nonsmokers exposed to secondhand smoke at home or work
increase their risk of developing heart disease by 25 to 30 percent and
lung cancer by 20 to 30 percent. In addition, secondhand smoke causes
respiratory problems in nonsmokers such as coughing, phlegm, and
reduced lung function. Children exposed to secondhand smoke are at an
increased risk for sudden infant death syndrome, acute respiratory
infections, ear problems, and more severe asthma.
Health Hazards
Since
1964, 28 Surgeon General's reports on smoking and health have concluded
that tobacco use is the single most avoidable cause of disease,
disability, and death in the United States. In 1988, the Surgeon
General concluded that cigarettes and other forms of tobacco, such as
cigars, pipe tobacco, and chewing tobacco, are addictive and that
nicotine is the drug in tobacco that causes addiction. Nicotine
provides an almost immediate "kick" because it causes a discharge of
epinephrine from the adrenal cortex. This stimulates the central
nervous system and endocrine glands, which causes a sudden release of
glucose. Stimulation is then followed by depression and fatigue,
leading the user to seek more nicotine.
Nicotine is absorbed
readily from tobacco smoke in the lungs, and it does not matter whether
the tobacco smoke is from cigarettes, cigars, or pipes. Nicotine also
is absorbed readily when tobacco is chewed. With regular use of
tobacco, levels of nicotine accumulate in the body during the day and
persist overnight. Thus, daily smokers or chewers are exposed to the
effects of nicotine for 24 hours each day. Adolescents who chew tobacco
are more likely than nonusers to eventually become cigarette smokers.
Addiction
to nicotine results in withdrawal symptoms when a person tries to stop
smoking. For example, a study found that when chronic smokers were
deprived of cigarettes for 24 hours, they had increased anger,
hostility, and aggression, and loss of social cooperation. Persons
suffering from withdrawal also take longer to regain emotional
equilibrium following stress. During periods of abstinence and/or
craving, smokers have shown impairment across a wide range of
psychomotor and cognitive functions, such as language comprehension.
Women
who smoke generally have earlier menopause. Pregnant women who smoke
cigarettes run an increased risk of having stillborn or premature
infants or infants with low birth weight. Children of women who smoked
while pregnant have an increased risk for developing conduct disorders.
National studies of mothers and daughters have also found that maternal
smoking during pregnancy increased the probability that female children
would smoke and would persist in smoking.
In addition to
nicotine, cigarette smoke is primarily composed of a dozen gases
(mainly carbon monoxide) and tar. The tar in a cigarette, which varies
from about 15 mg for a regular cigarette to 7 mg in a low-tar
cigarette, exposes the user to an increased risk of lung cancer,
emphysema, and bronchial disorders.
The carbon monoxide in
tobacco smoke increases the chance of cardiovascular diseases. The
Environmental Protection Agency has concluded that secondhand smoke
causes lung cancer in adults and greatly increases the risk of
respiratory illnesses in children and sudden infant death.
Promising Research
Research
has shown that nicotine, like cocaine, heroin, and marijuana, increases
the level of the neurotransmitter dopamine, which affects the brain
pathways that control reward and pleasure. Scientists have pinpointed a
particular molecule [the beta 2 (b2)] subunit of the nicotine
cholinergic receptor as a critical component in nicotine addiction.
Mice that lack this subunit fail to self-administer nicotine, implying
that without the b2 subunit, the mice do not experience the positive
reinforcing properties of nicotine. This finding identifies a potential
site for targeting the development of nicotine addiction medications.
Other
research found that individuals have greater resistance to nicotine
addiction if they have a genetic variant that decreases the function of
the enzyme CYP2A6. The decrease in CYP2A6 slows the breakdown of
nicotine and protects individuals against nicotine addiction.
Understanding the role of this enzyme in nicotine addiction gives a new
target for developing more effective medications to help people stop
smoking. Medications might be developed that can inhibit the function
of CYP2A6, thus providing a new approach to preventing and treating
nicotine addiction.
Another study found dramatic changes in the
brain's pleasure circuits during withdrawal from chronic tobacco use.
These changes are comparable in magnitude and duration to similar
changes observed during withdrawal from other abused drugs such as
cocaine, opiates, amphetamines, and alcohol. Scientists found
significant decreases in the sensitivity of the brains of laboratory
rats to pleasurable stimulation after nicotine administration was
abruptly stopped. These changes lasted several days and may correspond
to the anxiety and depression experienced by humans for several days
after quitting smoking "cold turkey." The results of this research may
help in the development of better treatments for the withdrawal
symptoms that may interfere with individuals' attempts to quit.
Treatment
Some
individuals simply are able to stop smoking. For others, studies have
shown that pharmacological treatment combined with behavioral
treatment, including psychological support and skills training to
overcome high-risk situations, results in some of the highest long-term
abstinence rates. Generally, rates of relapse for smoking cessation are
highest in the first few weeks and months and diminish considerably
after about 3 months.
Behavioral economic studies find that
alternative rewards and reinforcers can reduce cigarette use. One study
found that the greatest reductions in cigarette use were achieved when
smoking cost was increased in combination with the presence of
alternative recreational activities.
Nicotine chewing gum is one
medication approved by the Food and Drug Administration (FDA) for the
treatment of nicotine dependence. Nicotine in this form acts as a
nicotine replacement to help smokers quit smoking. The success rates
for smoking cessation treatment with nicotine chewing gum vary
considerably across studies, but evidence suggests that it is a safe
means of facilitating smoking cessation if chewed according to
instructions and restricted to patients who are under medical
supervision.
Another approach to smoking cessation is the
nicotine transdermal patch, a skin patch that delivers a relatively
constant amount of nicotine to the person wearing it. A research team
at NIDA's Intramural Research Program studied the safety, mechanism of
action, and abuse liability of the patch that was consequently approved
by FDA. Both nicotine gum and the nicotine patch, as well as other
nicotine replacements such as sprays and inhalers, are used to help
people fully quit smoking by reducing withdrawal symptoms and
preventing relapse while undergoing behavioral treatment.
Another
tool in treating tobacco addiction is a medication that goes by the
trade name Zyban. This is not a nicotine replacement, as are the gum
and patch. Rather, this works on other areas of the brain, and its
effectiveness is in helping to make nicotine craving, or thoughts about
cigarette use, more controllable in people who are trying to quit.
Extent of Use
Monitoring the Future Survey (MTF)
Despite
the demonstrated health risks associated with cigarette smoking, young
Americans continue to smoke. However, 30-day*** smoking rates among
high school students have declined from peaks reached in 1996 for
8th-graders (21.0 percent) and 10th-graders (30.4 percent) and in 1976
for 12th-graders (38.8 percent). In 2005, 30-day rates had dropped to
9.3 percent for 8th-graders, 14.9 percent for 10th-graders, and 23.2
percent for 12th-graders.
The decrease in smoking rates among
young Americans corresponds to several years in which increased
proportions of teens said they believe there is a "great" health risk
associated with cigarette smoking and expressed disapproval of smoking
one or more packs of cigarettes a day. Students' personal disapproval
of smoking has risen for some years. In 2005, for example, the
percentage of 12th-graders disapproving of smoking one or more packs of
cigarettes per day increased significantly, from 76.2 percent in 2004
to 79.8 percent in 2005.
Other Information Sources
For additional information on tobacco abuse and addiction, please visit www.smoking.drugabuse.gov.
For more information on how to quit smoking, please visit www.cdc.gov/tobacco.
*
NSDUH (formerly known as the National Household Survey on Drug Abuse)
is an annual survey of Americans age 12 and older conducted by the
Substance Abuse and Mental Health Services Administration. Copies of
the latest survey are available at www.samhsa.gov and from the National Clearinghouse for Alcohol and Drug Information at 1-800-729-6686.
**
These data are from the 2005 Monitoring the Future Survey, funded by
the National Institute on Drug Abuse, National Institutes of Health,
DHHS, and conducted annually by the University of Michigan’s Institute
for Social Research. The survey has tracked 12th-graders’ illicit drug
use and related attitudes since 1975; in 1991, 8th- and 10th-graders
were added to the study. The latest data are online at www.drugabuse.gov.
***
"Lifetime" refers to use at least once during a respondent's lifetime.
"Annual" refers to use at least once during the year preceding an
individual’s response to the survey. "30-day" refers to use at least
once during the 30 days preceding an individual’s response to the
survey.
Source: National Institute of Drug Abuse
Dr. Jeffrey Speller
Dr. Tanya Korkosz
Psychopharmacology Associates of New England
www.psychopharmassociates.com
