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WHAT IS THE EFFECT
OF THE ADDICTION
GENE ON A SMOKING
ADDICTION?
2018-2019
J o y c e S t r a v e r
E v a N i e u w e n h u i j s
smoking addiction Page 01
CONTENTS
1 . W h a t i s a s m o k i n g a d d i c t i o n ?
1 . 1 W h a t i s a n a d d i c t i o n ?
1 . 2 e f f e c t s o n a s m o k i n g a d d i c t i o n
2 . W h i c h f a c t o r s p l a y a r o l e i n a s m o k i n g a d d i c t i o n ?
2 . 1 s o c i a l f a c t o r s
2 . 2 a v a i l a b i l i t y f a c t o r s
2 . 3 b e h a v i o r a l f a c t o r s
2 . 4 p e r s o n a l f a c t o r s
3 . H o w d o e s t h e a d d i c t i o n g e n e h a v e i n f l u e n c e o n
a s m o k i n g a d d i c t i o n ?
3 . 1 w h a t i s t h e a d d i c t i o n g e n e ?
3 . 2 i n t e r v i e w a d d i c t i o n w i t h p r o f . d r . V e r w e i j
4 , C o n c l u s i o n
5 . D i s c u s s i o n
6 . S o u r c e s
smoking addiction Page 02
1. WHAT IS A SMOKING ADDICTION?
1.1 WHAT IS ADDICTION?
An addiction is a state in which a person
is mentally or physically dependent on
something. This can be a habit, an
action, a feeling or a substance. This
usually goes at the expense of other
activities, since you cannot stop this
addiction easily. We can divide
addictions into two groups: a habit
addiction or a substance addiction. A
habit addiction is when a person does a
specific activity that gives them a kick
and makes them feel good. Examples of
these habits are: gaming, sex, gambling
and shopping. A substance addiction is
when a person is addicted to one or
more substances. People who have a
substance addiction are not addicted to
the kick, but the substance has a direct
influence on the brain, that is why these
substances are also called psychoactive
substances. Psychoactive substances
can also be divided in three groups:
- Stimulating substances: cocaine,
nicotine
- Numbing substances: alcohol, opium
- Psychedelic substances: XTC, LSA
The most common addictions are nicotine
and alcohol. In the Netherlands,
600.000 people have a tobacco
addiction and 480.000 people have an
alcohol addiction This indicates that a
smoking addiction is a big problem in the
Netherlands.
25% of the Dutch population above the
age of 15 smokes, whereof most are
addicted as well. The habit of smoking
and the nicotine are the cause of the
addiction. The nicotine in the tobacco
works as a mental and physical
addiction. Nicotine stimulates the
production of dopamine which causes a
moment of joy and delight. This shows
that there is a relation between
dopamine and the reward center in the
brain. When someone experiences a
moment of joy the brain produces
dopamine, this happens
O when brain wants you eat, another
drink, moment have sex, of exercise, joy
and the do person drugs and will when
repeat you the smoke. same action.
After this, Thethe
brain will produce dopamine again and
this can cause an addiction. (The brain
links fun situations with lighting a
cigarette. That's why you also see many
people smoking at a party.)
smoking addiction Page 03
1.1 WHAT IS ADDICTION?
Exercising also produces dopamine in
the body. Which happens with a smoking
addiction as well. Dopamine keeps you
motivated to keep going, gives a sense
of reward and makes you happy. Not
only does the brain produce dopamine
when you sport but it also produces
endorphin and serotonin; all
neurotransmitters. A neurotransmitter or
transfer agent is a signal substance that
transmits nerve impulses in synapses
between nerve cells ('neurons') in the
nervous system or transmits impulses
from motor nerve cells to muscle cells or
nerve receptors on sensory nerve cells.4
Endorphin gives you a euphoric feeling
and reduces pain. That is why it is
called the 'feel good' drug. Serotonin,
also called the happiness hormone,
gives you a blissful feeling and
regulates your appetite, mood and
sleep.
Besides the fact that you can get
addicted to cigarettes, there are a lot
of other processes that will occur in the
brain, which will have a negative effect
on the smoker.
The brain will not process important
information anymore, which can be very
harmful. This was one of the results of a
research done by American Harvard.
They observed 31 chain-smokers (more
than 15 cigarettes a day) and 31
nonsmokers by letting them gamble with
100 dollars, while they were lying in a
brain scan. This showed that smokers
ignore important information. The
smokers seem to be focusing on the
actual profit and loss, but not on what
their profit or loss would be if they
made another decision. From their point
of view that is not important. On the
contrary, the nonsmokers were focusing
on the profit or loss they would get if
they made another decision. The
nonsmokers left with more money than
the smokers.
Lung cancer, a heart attack and
impotence; smokers know the
consequences of smoking, but why do
they keep smoking? This is the same
problem as with the 100dollar
experiment; they ignore the important
information. This is really confusing for
the smoker, because they process the
information, they know the
consequences and know O the
importance of those. But before they
light their next cigarette, their
subconscious state loses the information
somewhere in the brain. So, before they
even think about it, they smoke another
cigarette. They feel like this cigarette is
even better than the previous one,
which of course is not true, because the
brain does not produce more dopamine.
smoking addiction Page 04
1.1 WHAT IS ADDICTION?
Smokers indeed seem to overestimate
the pleasure of smoking. Many smokers
acknowledge that life with cigarettes
might be riskier, but more fun. Research
indicates that this is not true. Even so,
smoking makes you unhappier. The
average level of happiness in the
'smokers' group was well below that of
the 'non-smokers' and 'exsmokers'
groups. On top of that; according to
Spanish and American researchers,
smoking and depression seem to relate
to each other. They observed 8000
Spanish smokers and 9000 Finnish
smokers for over a period of 6 years
and compared them to non-smokers.
They found out that smokers have a
bigger change of becoming depressed
than nonsmokers, a 40% chance as
opposed to the non-smokers.
Also, the Harvard researchers are
convinced that the o peculiar
characteristics of smokers' brains are at
least partly caused by smoking. Another
part may well be a matter of aptitude:
characteristics that we have from birth
that makes it easier for people to start
with smoking.
It seems like the substances of a
cigarette changes the brain. And so, the
smoker will overestimate the importance
of smoking. The Harvard study explains
why most advice and campaigns do not
work. The warnings on cigarette boxes
(smoking kills) will probably only ensure
that smokers will become extra
convinced that smoking is nice. They do
not associate smoking with sickness and
death, but with pleasure, because they
would rather live a riskier life.
smoking addiction Page 05
1. WHAT IS A SMOKING ADDICTION?
1.2 EFFECTS ON A SMOKING ADDICTION
Everyone knows nowadays that smoking
kills you, it even says so on the
package. You will not notice many
effects at the start of smoking, because
it will begin to show in the course of
time. The most harmful substances in a
cigarette are nicotine, tar and carbon
monoxide.
Tar is a black sticky substance that
sticks on the cilia of the mucous
membrane. As a result, the cilia become
less mobile and more damaged. They
cannot abduct the dirt and dust that
well anymore. As said before, nicotine is
the addictive substance in a cigarette.
It is transported to the brain within 7
seconds, where it affects the process of
releasing adrenaline. This causes a high
heart rate and high blood pressure.
After one and a half hours after
smoking the cigarette, half of the
nicotine disappears within the body and
the smoker will feel uneasy and will
want to smoke another cigarette as soon
as possible. Carbon monoxide is a
colorless and odorless gas that enters
your lungs during smoking. This blocks
the way to get oxygen to the organs.
This will reduce the performance of the
organs. Furthermore, it will damage the
walls of vessels, making it easier to
deposit fat and calcium, which leads to
arteriosclerosis and thereafter to heart
diseases.
Moreover, there are of course many
other risks when you smoke daily.
These can be short term or long term.
Short-term:
- Condition: smoking will cause the
carbon monoxide to block the oxygens
way to the lungs, which will result in
your other organs not getting enough
oxygen and your condition will worsen.
- Odor: The smoke will stay
everywhere. In your clothes, hair, room
and your breath, which is not pleasant
for bystanders.
- Nicotine poisoning: This often occurs
when a person begins smoking. The
smoker will get dizzy, nauseous and
even vomit. When it is a heavy
poisoning, o people sometimes fall into
a coma. This can happen when a small
infant eats a cigarette.
- Second hand smoke: When someone
in your surrounding area smokes, 85% of
the smoke will get into the air and
eventually in your lungs as well. So even
if you do not smoke, there is still a
chance the smoke from your smoker
friends will affect you.
smoking addiction Page 06
1.2 EFFECTS ON A SMOKING ADDICTION
Long-term:
- Chronic bronchitis: this is a chronic
infection in the mucous membrane which
causes you to cough. This can damage
your alveoli.
- Lung emphysema: this happens when
your alveoli are damaged or completely
gone. It causes shortness of breath,
because your lungs got smaller which
makes it harder to give oxygen to the
rest of your body.
- (lung) cancer: this is caused by
abnormal cell growth in damaged places
in the lungs, which can result in cancer.
- Heart and vascular disease: Nicotine
and carbon monoxide damage your veins
throughout your whole body. Cholesterol
and other cells can build up in a certain
part of one of your veins which can
cause a blockage. This can be very
dangerous, because it can result in a
heart attack.
- Gastrointestinal disorders: when
smoking, you have a greater chance of
getting gastrointestinal disorders.
- Bad skin and teeth: Tobacco causes
the skin and teeth to look old and
unhealthy.
This is because too little oxygen is in
your body.
- Vocal cords: Due to mucus and the
coughing, your vocal cords get
damaged or infected. The clearness of
the voice will be lost.
- Memory: Smoking can have a very
negative influence on your memory.
- Pregnancy: Smoking while pregnant,
is very dangerous for the unborn child.
the fetus will grow slower and will also
get the toxic substances in his or her
blood by the mother. This can have very
bad consequences.
Moreover, there are of course many
other risks when you smoke daily.
smoking addiction Page 07
2.0 WHICH FACTORS PLAY A ROLE IN A
SMOKING ADDICTION?
Studies have shown that people under
the age of twenty are more likely to
start smoking than people above the
age of twenty. There are more men than
women that smoke regularly. On
average, 3,2% of students between the
age of 12 through 16 smoke daily, thus
have a smoking addiction. Studies have
also shown that foreigners are more
likely to have a smoking addiction than
non-foreigners. For example, 59% of
Turkish men living in the Netherlands
have a smoking addiction, whereas 31%
of Dutch men have a smoking addiction.
There is a bigger chance that teenagers
with divorced parents will start smoking.
People with a higher socioeconomic
status are less likely to start smoking
than people with a lower socioeconomic
status. On average, 6,7% of students
doing vmbo-b smoke daily, whereas
0,8% of students doing \ANO smoke
daily. There are a lot of factors that can
cause a smoking addiction. There are
social factors, availability factors,
personal factors and behavioral factors.
2.1 SOCIAL FACTORS
Under social factors we think of (for
example) the role their parents have; if
the parents smoke and what they think
of smoking. There is a bigger chance
that children with parents that smoke
will also start smoking.
U If the parents think it is normal to
smoke, then their child will probably
think the same. A study (Emory et al.,
2010) researching 19 other studies,
showed that by 16 of the 19 studies,
researchers found a connection between
non-smoking rules of parents and their
adolescent children. This study has
shown that the association between
rules of the parents and their children
came out to be stronger in families
where the parents did not smoke.
Moreover, another study showed that
non-smoking rules have a protective
impact on the transition between
nonsmoking and experimenting with
smoking. Setting up non-smoking rules
when they already are experimenting
with smoking is less effective.
They also found that non-smoking rules
had no effect when the father smoked,
but when the father did not smoke the
rules did have effect. They concluded
that when the behavior of the father did
not match the rules, the rules would not
have any effect on the adolescent.
Not only the parents play a role, their
friends do too. It is very common, peer
pressure. Adolescents fear rejection of
their smoking friends. They believe that
if they do not smoke, they will not be
part of the group. So, they will start
smoking to feel like they belong in the
group.
smoking addiction Page 08
2.0 WHICH FACTORS PLAY A ROLE IN A
SMOKING ADDICTION?
2.2 AVAILABILITY
Availability factors also play a role in a
smoking addiction. When the price of
cigarettes decrease, people are more
likely to buy them since they are
cheaper. So how much does it cost
(nowadays) to be a smoker daily? On
average, a chain smoker smokes 10
cigarettes a day. One pack of cigarettes
contains 19 cigarettes (Marlboro), which
costs 6 euros. 10 x 7 = 70 cigarettes per
week, which is 3,7 packs a week. This
means 191 ,6 packs a year, which is
equal to 191 ,6 x 6= 1.149,47 euros a
year. So, smoking is not only bad for
you, it also empties your wallet.
2.3 BEHAVIORAL
Research shows that a smoking
addiction is related to behavioral
factors such as driving under the
influence of alcohol, antisocial behavior
(aggression, theft and vandalism),
unsafe sexual behavior and poor school
performance. It is a pattern of
rebellious, recalcitrant and deviant
behavior. When doing one rebellious
act, people are often inclined of
continuing these acts, whereas smoking
is one of them.
2.4 PERSONAL
Personal factors also have influence on
a smoking addiction. When speaking of
personal factors, you can think of the
ability to resist peer pressure when it
comes to smoking. Depression, other
mental illnesses and personality traits
such as thrill- and sensation seeking and
being extrovert are also personal
factors which can lead to a smoking
addiction. Then of course, biologic
factors, which the rest of our paper will
be about. Some people are more
sensitive to addictions than others, due
to a genetic predisposition. We will
focus on this specific factor throughout
the rest of the paper.
smoking addiction Page 09
3. HOW DOES THE ADDICTION GENE HAVE
INFLUENCE ON A SMOKING ADDICTION?
3.1 WHAT IS THE ADDICTION GENE?
There are many ways that genes could
cause one person to be more vulnerable
to addiction than another. --Dr. Glen
Hanson
The results were that adolescents from
the age of 12 through 14 were only
influenced by their environment, not
their genes, as you can see here.
It is not just one gene that says, 'you
will get an addiction later in your life,'
because genetics do play a role, but not
as big a role as environmental factors.
Addiction vulnerability is a very
complex trait, thus finding addiction
genes is difficult as well. Not every
person who is an addict, will have the
same gene and not everyone who has
the addiction gene will show addiction
symptoms.
The addiction gene is inheritable, so it
often runs in families. On the right, you
can see an example of how the gene can
affect a family tree. The red are
carriers of the gene and the white are
non-carriers of the gene. To study the
addiction gene, researchers compare
the DNA of a large family that shows
symptoms of vulnerability for addiction.
But as adolescents move from initial
experimentation, to more established
regular pattems of use, their genes
become important and the effect of
environmental factors drastically drops,
as you can see down here.
Dr. Danielle Dick researched that some
people are born with a certain sequence
DNA that makes us more at risk
OLearn.Genetics for addictions or
mental illnesses. With the help of other
researches in Finland, she researched
the drinking behavior of young
adolescents ( 12-14 ) until their early
adulthood.
smoking addiction Page 10
3.2 INTERVIEW WITH PROF. DR. VERWEIJ
We asked prof. Dr. Verweij if she would
be open for an interview with us. She
agreed and we went to AMC in
Amsterdam to ask her certain questions
about addiction and genes. The
questions and their answers are as
followed:
How does an addiction develop?
Starting to use cigarettes, alcohol but
also cannabis is partly genetically
explainable; about 40% is caused by
genes and the other 60% is caused by
your environment. What kind of friends
you have, where you live and what you
experience in life. Especially the step
from habitual use to becoming an addict
depends on your DNA. When you are an
addict, it is already decided for 70% in
your DNA that you would be an addict,
but the other 30% of environmental
factors have to influence the rest of the
addiction. What the drug does to your
brain and how much of the drug you
want to use is already saved in O your
DNA.
How does an addict behave and
what happens in their brain?
In the brain there is a so-called reward
center, which plays an important part in
normal life. If you are hungry, then you
go eat, which results in getting a
'reward' in your brain. This rewarding is
for all kinds of habits or substances like
food, alcohol, cigarettes or sex. To make
sure you enact this behavior, you get
rewarded, which also applies when you
take cannabis or nicotine. So, what
happens to an addict; they use a drug
and feel the reward in their brain, which
goes away after a while and then they
want to get back to that feeling of
reward. How strongly you urge to get
the feeling of reward again, is different
for each person. But the urge is
stronger for an addict than a nonaddict.
Addicts get used to this feeling
and are in the need for more of the drug
every time they use. When the addiction
is bad, they will get withdrawal
symptoms after a day of not using.
smoking addiction Page 11
3.2 INTERVIEW WITH PROF. DR. VERWEIJ
What is the addiction gene and is
it heritable?
The addiction gene is heritable, and
you often see in families that when a
brother, sister, father or mother is
addicted, you have a higher chance to
becoming addicted too. The o addiction
gene is not one gene, there are a lot;
hundreds and maybe thousands of little
genes and they all play a little role in an
addiction. For example, by smoking we
found a couple of pieces where we are
sure of that they do something to fortify
the addiction, such as the nicotinereceptor
gene, which is a gene that
plays a role in the adhesion of nicotine.
Everyone has this gene, but we all have
different versions of this gene. With one
version you have a bigger chance to
become an addict and with the other
version you have a minor chance of
becoming an addict. Most people who
are addicted to cigarettes, often have
that specific gene. But, because there
are hundreds of genes that play a role,
it does not mean that when you have
that one specific gene you will become
an addict. The addiction gene is not
something that exists, it is a whole
group of different genes.
Does the addiction gene have
impact on the smoking behavior of
a chain smoker?
Since it is not just one gene that
influences an addiction and it is not just
genes that influence an addiction, it is
very hard to tell. But these genes can
be fortified in combination with
environmental factors. Though, these
genes can influence how addicted
someone gets and how much you smoke.
smoking addiction Page 12
3.2 INTERVIEW WITH PROF. DR. VERWEIJ
What percentage of the people
with an addiction gene get an
addiction?
That is hard to say, suppose there are a
thousand genes that play a role, and if
you have all those bad variants of those
genes then the chances are much higher
than when you do not have all those bad
variants. But usually you do not have all
those bad genes, you also do not have
zero of those bad genes; it is always
somewhere in between. In addition, you
have the environmental factors. If you
grow up in a family where no one
smokes and you go to a school where no
one smokes while you have all those bad
variants of those genes, you might have
a bigger risk of becoming addicted
when looking at the heritable side, but
your environment does not trigger those
genes
and you will not get addicted. Mostly it
is a combination of your DNA and your
environment.
You can look at this by twins; they have
the same DNA, often also the same home
situation but a different social
environment, especially their group of
friends. So even though they have the
same DNA, it does not mean they follow
the same path. Their environment also
plays a very big role.
Do adolescents have a bigger
chance to have a drug addiction
when the start smoking at an early
age?
If you start smoking at an early age,
then yes, you have a bigger chance of
getting addicted to another substance.
People who start at an early age will,
from a genetically point of view, be
more sensitive to other addictions. If
you start with something more innocent
like cannabis, you will say yes to hard
drugs more easily than someone who is
not addicted to something like cannabis.
smoking addiction Page 13
3.2 INTERVIEW WITH PROF. DR. VERWEIJ
Which substance do people with
the addiction gene most likely get
addicted to?
This is different for everyone, so it is
hard to say. In the Netherlands, it will
most likely be alcohol, since it is socially
acceptable. When it is socially
acceptable, some people might drink
more, which often leads to an alcohol
addiction. A big factor is how easily you
can get your hands on a substance.
Alcohol and cigarettes are legal (above
the age of 18) and thus easily
obtainable. But heroin for example, a
very addictive substance, is very hard
to get your hands on and thus not easily
obtainable. That is why there are less
people addicted to heroin than people
who are addicted to alcohol or
cigarettes.
Do people with for example ADHD
have a bigger chance of
developing an addiction when they
have the addiction gene? If so, do
these genes strengthen each
other?
ADHD influences addictions, because
people with ADHD are often more
impulsive, so they are more likely to use
a substance faster. They often show
risky behavior.
Is the addiction gene difficult to
do research on?
Yes, you need very big groups of people
to research, because the effect is so
small. A new study (which is not
published yet) has about one million test
subjects, who gave their DNA and filled
in a questionnaire. Nowadays,
researches can genotype their whole
DNA. So, researchers can compare
certain parts of the DNA and look at the
different variants. This can show how
the DNA of a smoker can differ from the
DNA from a nonsmoker. Technically, it is
not very difficult, but it is a very big
group to genotype, so it costs a lot of
time.
Does raising the price of
cigarettes help stop the addiction?
Yes, it works. Australia is a good
example; the price of a pack of
cigarettes is 20 euros. Compared to the
Netherlands, that's three times its price.
This high price resulted in less smokers
in Australia. Also, the Netherlands
changed the legal age of smoking from
16 to 18. These measures had an
influence on the smoking behavior of
adolescents and adults. The measures
especially help people who have not
smoked yet before, rather than people
who already smoke.
smoking addiction Page 14
3.2 INTERVIEW WITH PROF. DR. VERWEIJ
How do you recover from an
addiction?
Do you think there is an effective
way to prevent an addiction?
You can get medication like nicotine
patches to get rid of your smoking
addiction. But most importantly, you
must change your behavior. The physical
part of getting rid of an addiction, is
easy with the right medication, but it is
the mental part of getting rid of an
addiction which is the hardest. Often,
cognitive behavior therapy is given to
be mentally prepared to quit your
addiction.
Raising the price of cigarettes and
getting rid of smoking areas for
example, is an effective way to make it
harder to smoke and thus preventing
people from having an addiction. If you
make sure people do not start smoking,
then we do not have to convince people
to stop. So, prevent the problem, rather
than solving it.
smoking addiction Page 15
4. CONCLUSION
So, what is the effect of the addiction
gene on a smoking addiction? The
answer is not that simple. That is
because the addiction gene does not
really exist in a singular definition.
There is not one bad gene that causes
an addiction, there are thousands of
genes that play a little role when it
comes to becoming more sensitive to
developing an addiction. Because they
play such a tiny role, they all have little
effect on developing an addiction. All
these genes are hard to genotype and
that is why it is so hard to say if
someone has a bigger chance in
developing an addiction.
Not only our genes play a role when it
comes to addiction, our environment
plays a big role as well. By environment
we mean friends, family, school, sports
etc. Our environment is 60% influential
and our genes 40%. So even when you
have "bad" genes you do not have to
develop an addiction when living in a
"good" environment. It also applies the
other way around; when you do not
have the "bad" genes but live in an
environment where having an addiction
is very likely, you can also get an
addiction.
So, when it comes to a smoking
addiction, it really depends on what
kind of person you are. Cigarettes are
easily available for almost all ages,
even though it is illegal for people under
the age of eighteen, which is also a big
factor when it comes to addiction. You
can get your hands on cigarettes easier
than getting your hands on, for
example, heroin.
When looking at the bigger picture, not
much research has been done when it
comes to what the effect of genes is on
a smoking addiction. But it has been
proven that genes do have an impact on
a lot of actions.
smoking addiction Page 16
5. DISCUSSION
When looking at our whole paper, we
were happy with the subject we were
doing research on. The subject suited us
both and we were genuinely interested.
The cooperation between us was also
very good, since we never argued or
had any problems during this project.
We first wanted to research DNA of
adolescents who smoked and compare
their DNA and environment, but there
was too little time and it would cost too
much money. That is why we decided to
interview an expert on the subject: Prof.
dr. Verweij. She told us a lot of valuable
information for our main question, some
of which is not even published yet. We
were also very happy with her
cooperation.
We sincerely hope our research caught
your attention and helped you
understand how addictions and genes
can influence each other.