Cigarette smoking
Holy Quran said
in
[the cow versa ]
[195] and make
not your own hands contribute to (your) destruction
Cigarettes
and Other Nicotine
Nicotine is one
of the most heavily used addictive drugs in the United States. Cigarette smoking
has been the most popular method of taking nicotine since the beginning of the
20th century. In 1998, 60 million Americans were current cigarette smokers (28
percent of all Americans aged 12 and older), and 4.1 million were between the
ages of 12 and 17 (18 percent of youth in this age bracket).
In 1989, the
U.S. Surgeon General issued a report that 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. In
addition, the report determined that smoking was a major cause of stroke and the
third leading cause of death in the United States.
Health
Hazards
Nicotine is
highly addictive. It is both a stimulant and a sedative to the central nervous
system. The ingestion of nicotine results in an almost immediate "kick" because
it causes a discharge of epinephrine from the adrenal cortex. This stimulates
the central nervous system, and other endocrine glands, which causes a sudden
release of glucose. Stimulation is then followed by depression and fatigue,
leading the abuser 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. Nicotine taken in by cigarette or cigar smoking takes only seconds to
reach the brain but has a direct effect on the body for up to 30 minutes.
Research has
shown that stress and anxiety affect nicotine tolerance and dependence. The
stress hormone corticosterone reduces the effects of nicotine; therefore, more
nicotine must be consumed to achieve the same effect. This increases tolerance
to nicotine and leads to increased dependence. Studies in animals have also
shown that stress can directly cause relapse to nicotine self-administration
after a period of abstinence.
Other studies
have shown that animals cannot discriminate between the effects of nicotine and
the effects of cocaine. Studies have also shown that nicotine
self-administration sensitizes animals to self-administer cocaine more readily.
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. If women smoke cigarettes and also take oral
contraceptives, they are more prone to cardiovascular and cerebrovascular
diseases than are other smokers; this is especially true for women older than
30.
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.
Adolescent
smokeless tobacco users are more likely than nonusers to become cigarette
smokers. Behavioral research is beginning to explain how social influences, such
as observing adults or other peers smoking, affect whether adolescents begin to
smoke cigarettes. Research has shown that teens are generally resistant to many
kinds of anti-smoking messages.
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 a high
expectancy rate of lung cancer, emphysema, and bronchial disorders. The carbon
monoxide in the 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 now have pinpointed a particular molecule (the
beta 2 subunit of the nicotine cholinergic receptor) as a critical component in
nicotine addiction. Mice that lack this molecule fail to self-administer
nicotine, implying that without the b2 molecule, the mice do not experience the
positive reinforcing properties of nicotine. This new finding identifies a
potential site for targeting the development of anti-nicotine addiction
medications.
Other new
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 nicotine use. These changes are comparable in magnitude and duration to
similar changes observed during the 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 individual's attempts to quit
smoking.
Treatment
Research
suggests that smoking cessation should be a gradual process because withdrawal
symptoms are less severe in those who quit gradually than in those who quit all
at once. Rates of relapse are highest in the first few weeks and months and
diminish considerably after 3 m-months.
Studies have
shown that pharmacological treatment combined with psychological treatment,
including psychological support and skills training to overcome high-risk
situations, results in some of the highest long-term abstinence rates.
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 the smoking habit.
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 Division of Intramural Research 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 nicotine addiction is a medication that goes by the trademark 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
controllable nicotine craving or thoughts about cigarette use in people trying
to quit.
In the future,
a nicotine vaccine may be an effective method for preventing and treating
tobacco addiction. The vaccine would prevent nicotine from reaching the brain so
as to reduce its effects and help keep people from becoming addicted.
Scientists
recently developed an experimental nicotine vaccine consisting of a nicotine
derivative attached to a large protein. The scientists injected a single dose of
nicotine into vaccinated rats and found that the amount of nicotine reaching the
brain was reduced by 64%. Further, the researchers found that administering
doses of nicotine antibodies similar to those that are ordinarily produced by
the vaccine greatly reduced the rise in blood pressure produced by a nicotine
injection. The antibodies also completely prevented the increased movements
ordinarily seen when rats are injected with nicotine.
The next steps
will be to conduct additional safety studies, followed by clinical trials with
the vaccine in human volunteers. These clinical trials are currently scheduled
to begin in early 2002.
Monitoring the
Future Study (MTF)*
Prevalence
rates for smoking among young people remain high, in spite of the demonstrated
health risk associated with smoking. Since 1975, cigarettes have consistently
been the substance the greatest number of high school students use daily.
Between 1998
and 1999, however, past month smoking decreased significantly among 8th graders,
from 19.1 percent to 17.5 percent, and rates of use were stable or slightly
decreased for 10th graders (25.7 percent) and seniors (34.6 percent). Lifetime
and daily use also leveled off in 1999 among all grades, as did use of smokeless
tobacco.
Smoking 'causes
50% of gum disease'
Smoking may be
responsible for more than half of the cases of gum disease among adults in the
US, say researchers.
The study found
that current smokers are about four times more likely than people who have never
smoked to have advanced periodontal (gum) disease.
However, 11
years after quitting, former smokers were no more likely than non-smokers to
suffer from bad gums.
Researchers
from the Centers for Disease Control and Prevention analyzed US government
health data on 13,650 people aged 18 and older who had their own teeth.
Pregnant smokers'
legacy of diabetes
Smoking may lead
to fetal malnutrition
Women who smoke
during pregnancy are likely to expose their children to the risk of diabetes and
obesity in later life, according to research.
Young adults
who smoke are also more likely to be at increased risk of diabetes, the survey
suggests.
However, a
leading British expert says the link has not been fully proved by this study.
The Swedish
authors used British data on about 17,000 births during March 1958 to conduct
their study.
At birth,
midwives collected information on smoking during pregnancy (after four months).
Details of
maternal smoking were again recorded in 1974.
The group's own
smoking behaviors was recorded during an interview at age 16.
The offspring
were interviewed about diabetes when they were 33.
Among those
followed fully throughout childhood and adolescence to age 33, the authors
identified 15 men and 13 women who had developed diabetes between 16 and 33
years and 602 who were obese at age 33.
The conditions
are rare in this age group and although relatively few of the group as a whole
were affected, the incidence level was still a third more than doctors would
have normally expected.
The authors of
the report, which appears in the British Medical Journal, say the association of
diabetes with maternal smoking specifically during pregnancy, suggest it is a
true risk factor for type two diabetes, which emerges in adulthood.
The survey also
found study members without diabetes, but whose mothers smoked during pregnancy,
were significantly more likely to be obese or overweight by age 33 years.
The charity
Diabetes UK believes the report's findings are significant.
Smoke damage
A spokesman
said: "The number of people who developed diabetes is unusually high.
"It is not
known exactly what causes diabetes, only that it is partially genetic and
partially environmental factors.
"It is likely a
combination of factors will be involved.
"The suggested
link between smoking during pregnancy and obesity of the offspring is also
important because being overweight is known to increase the risk of developing
diabetes."
"To reduce the
risk of developing diabetes, people should follow a healthy balanced diet, take
regular exercise and not smoke."
Researchers
suggest in uterus exposure to smoking results in lifelong metabolic
dysfunction, possibly due to the fetus being malnourished or harmed by the
toxins in cigarette smoke.
University of
Liverpool consultant physician Dr John Wilding is cautious about the report's
findings.
The academic,
who specializes in diabetes and obesity, said: "More details are needed to
clarify whether the association is really true.
"I would agree
it's further reason to discourage women from smoking during pregnancy, but I
think it lacks proof."
A White Paper
published in 1998 committed the government to reducing the number of women who
smoke during pregnancy from 23% to 15% by the year 2010.
Lead researcher
Dr Scott Tomar said: "Cigarette smoking may well be the major preventable risk
factor for periodontal disease.
"The good news
is that quitting seems to gradually erase the harmful effects of tobacco use on
periodontal health."
The researchers
also found that the odds of developing gum disease were increased still further
by heavy smoking.
Dose effect
Smokers who
smoked less than half a pack per day were almost three times more likely than
nonsmokers to have periodontitis.
But those who
smoked more than a pack and a half per day had almost six times the risk.
Jack Caton,
president of the American Academy of Period ontology, said: "Everyday
periodontists see the destruction smoking causes in the mouths of their
patients.
"I hope the
staggering statistics from this study will compel even more dental care
providers to get involved in tobacco cessation efforts."
Smoking reduces
the delivery of oxygen and nutrients to the gums.
This damages
the healing process, and makes smokers' gums more susceptible to infection.
In addition to
being a major cause of tooth loss, periodontal disease has been linked to
increased risk of heart disease, stroke, diabetes, respiratory disease and
premature babies.
The research
was welcomed by the British Dental Association.
Chief executive
John Hunt said: "This is very useful research showing just how bad smoking can
be for your gums. If you want to keep your teeth, don't smoke."
The research is
published in the Journal of Period ontology.