Furii’s Flaming Finger’s
(A.K.A.: Team 1)
Possible Causes of
Schizophrenia
By: Andrew, Anne, Connie and Diana
Genetics - Interplay
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Experts now agree that schizophrenia develops as a result of
interplay between biological predisposition (for example, inheriting
certain genes) and the kind of environment a person is exposed to
(schizophrenia.com).
Schizophrenia researchers break down the causes of schizophrenia
into two categories:
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Genetic(s) (schizophrenia.com)
Environment (everything other than genes) (schizophrenia.com).:
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“Social, nutritional, hormonal and chemical environment in the womb of the
mother during pregnancy, up to the social dynamics and stress a person
experiences, to street drug use, education, virus exposure, vitamin use, and
much, much more” (schizophrenia.com).
Another way to think of this is “Nature vs. Nuture” or “genes vs.
environment” (schizophrenia.com).
Genetics - Examples
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An example of how a genetic predisposition for
schizophrenia can be triggered by environmental
influences can be seen in a research study taken from
Biological Psychiatry, Volume 57:
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Indicates that people who had multiple copies of a version of the
COMT gene and who smoked marijuana had a 1,000% increase
in their risk of developing schizophrenia (as cited on
schizophrenia.com).
Another example from the British Journal of Psychiatry:
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Indicates that adopted children with high genetic/biological risk
for schizophrenia (their mother had schizophrenia) had an 86%
lower rate of developing schizophrenia raised in a healthy vs. a
dysfunctional family. Only 6% of the children developed
schizophrenia in the healthy family. 37% of the children of the
dysfunctional families developed schizophrenia (as cited on
schizophrenia.com).
Genetics - Research
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There are multiple genes being researched right now that may be
contributing to the schizophrenia. There are about a dozen that are the
leading contributors (schizophrenia.com).
There is also research being done to investigate what biological molecules
may be responsible for turning on and off certain genes contributing to
schizophrenia (schizophrenia.com).
The predominance of these and other factors probably varies from person
to person in schizophrenia (Encyclopedia Britannica, 2008).
It is becoming more evident that having a gene or genes linked to
schizophrenia is just the start. If you aren’t exposed to the environmental
factors that contribute to schizophrenia, then it is likely you will never get it
(schizophrenia.com).
Having a predisposition and being exposed to certain environmental factors
certainly increases the chances of developing schizophrenia. The more
environmental factors you are exposed to, the higher the risk
(schizophrenia.com).
Genetics - Chart
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Experts now promote that schizophrenia along with all other mental illness is caused
by a combination of biological, psychological and social factors, this understanding is
called the bio-psycho-social model.
The following charts show the probable factors and path leading to the onset of
schizophrenia:
Chart taken from a presentation by Dr. Ira Glick, “New Schizophrenia Treatments”
(as shown on schizophrenia.com).
Genetics - Chart
Chart taken from a presentation by Dr. Ira Glick, “New Schizophrenia Treatments”
(as shown on schizophrenia.com).
Genetics – Family Studies
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Family risk studies:
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Compares the observed frequency of the mental illness in close relatives of a
patient vs. the frequency in the general population (Encyclopedia Britannica,
2008).
“First-degree relatives (parents, siblings, and children) share 50 percent of their
genetic material with the patient, and higher rates of the illness in these relatives
than expected indicate a possible genetic factor” (Encyclopedia Britannica,
2008).
Further information on the impact of genetics versus environmental factors can
be taken from comparing identical twins reared together with those reared apart
(Encyclopedia Britannica, 2008).
Adoption studies comparing children whose biological parents who had
schizophrenia with those whose parents did not can also be useful in separating
biological from environmental influences (Encyclopedia Britannica, 2008).
“These studies have demonstrated a clear role for genetic factors in the
causation of schizophrenia” (Encyclopedia Britannica, 2008).
Genetics – Risk Chart
The Dopamine Hypothesis
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States that the excess of dopamine
activity in the mesocortical dopamine
system produces the positive symptoms of
Schizophrenia.
This was discovered by accident in 1950
by Henri Laborit when he noticed that
antihistamine drugs prescribed to his
patients reduced anxieties without
producing mental confusion.
The Dopamine Hypothesis
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Chemist Paul Charpentier developed
chlorpromazine (antihistamine) and tested
it on animals which was later tested on
humans.
It proved to be an effective treatment only
for patients with schizophrenia by
alleviating or eliminating their
hallucinations and delusions.
How does this work you ask…
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Chlorpromine acts as a
dopamine antagonist by
blocking postsynapic
dopaminergic receptors
thus supporting the
dopamine hypothesis.
Other experiments show
that chlorpromine and
other antipsychotic drugs
selectively bind to
dopamine receptor sites.
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The Dopamine Hypothesis
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People with schizophrenia have
occasionally been found to have
abnormally high levels of dopamine
metabolites in their blood plasma.
In addition, drugs such as amphetamines
and cocaine that increase dopamine
activity in the CNS can often
produce positive symptoms of
schizophrenia in individuals
without this disorder.
The Hypofrontality Theory
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States that the negative symptoms of
schizophrenia are caused by decreased
activity in the prefrontal cortex.
In PET scans, it has shown that people
with schizophrenia show decreased
metabolic activity in the frontal region of
the brain.
Support for this Hypothesis
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Damage to the prefrontal cortex
in people who do not have
schizophrenia often have
motivational difficulties,
confusion, decreased speech,
flat affect, and social withdrawal.
Also researchers have concluded that the
negative symptoms of schizophrenia
reflect prefrontal cortex deficits.
Problems with this Theory
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Not all persons with
schizophrenia exhibit
hypofrontality
Recently in a metaanalysis involving more
than 4000 people with
schizophrenia,
hypofrontality was
exhibited in
approximately half of the
patients (Davidson &
Heinrichs, 2003)
Abnormal Brain Structure
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Enlarged ventricles
Smaller temporal and frontal lobes
Smaller amounts of gray matter
Abnormal blood flow
Abnormal amounts of neurotrophins
Disorganized hippocampal cells
Viral Infections and
Schizophrenia
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Fetal exposure to viral infections such as
influenza
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Many individuals with schizophrenia are born in winter
months
Toxoplasma gondii
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Intracellular parasite found in cat feces or uncooked
meat
Known to cause abortions and stillbirths
Can also cross the placenta and cause changes in
head size,deafness, cerebral palsy, mental retardation
and later in life- psychosis such as delusions and
hallucinations
Sociocultural Views
According
to Comer (2007), sociocultural theorists believe that people
with mental disorders are victims of social forces. They say that both
social labeling and family dysfunction contribute to the
development of schizophrenia.
Social Labeling: certain features of this disorder are influenced by the
diagnosis itself (Modrow,1992 as cited in Comer, 2008). The label of
schizophrenic is given to those persons in society that do not conform
to certain norms or behaviors.
Regardless of whether the label is justified or not, it does become a
self fulfilling prophecy, which then promotes the development of several
schizophrenic symptoms.
Being labeled “crazy” might encourage people to display psychotic
behaviors (they accept and play the role). Dangers of diagnostic
labeling (Rosenhan, 1973).
Family Dysfunction
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Theorists have said for years that certain patterns of family
interaction can promote or sustain schizophrenic symptoms.
Schizophrenia has often been linked to family stress (Boye et
al., 2002; Schiffman et al., 2002, 2001; Miklowitz et al., 1995
as cited in Comer, 2007). Parents with people who have
schizophrenia more times than not 1) display more conflict, 2)
have greater difficulty communicating with one another, 3) are
more critical of and over-involved with their children than
other parents. Family theorists have observed that some
families are high in express emotion. This means that the
family members criticize, disapprove of, are hostile towards
each other as well as intrude on one another’s privacy very
frequently.
People who have this disorder and live with such families are
four times more likely to relapse, while trying to recover
(Comer, 2007).
Double Bind Hypothesis
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This is a theory that says that some parents communicate mutually
contradictory messages to their children which places them in a
double bind situation. This causes the children to constantly
displease their parents “never doing anything right”.
Double-bind messages are primarily verbal and non-verbal
(contradictory metacommunication) (Comer, 2007).
Children repeatedly exposed to this kind of communication will
develop strategies to cope. Some children will ignore the primary
communication and respond to the non-verbal communication, they
become suspicious of what is being said to them (always trying to
figure out the meaning behind what is said), focus on clues in
gestures, tones. When one increasingly responds to messages in
this way, then they may move towards becoming a paranoid
schizophrenic (Comer, 2007).
Sociocultural-Existential View
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This is a theory that was developed by a clinical theorist named
R.D. Laing.
This theory combined sociocultural views with existential ones. It
argues that schizophrenia is a constructive process where people
try to cure themselves of the unhappiness and confusion caused
by their social environment. Liang said that if these people were
left alone then they would get better.
References
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In Depth Schizpophrenia Information and Support. Retrieved March 12,
2008, from www.schizophrenia.com:
http://www.schizophrenia.com/hypo.php
mental disorder. (2008). In Encyclopædia Britannica. Retrieved
March 9, 2008, from Encyclopædia Britannica Online:
http://search.eb.com/eb/article-32322
mental disorder. (2008). In Encyclopædia Britannica. Retrieved
March 9, 2008, from Encyclopædia Britannica Online:
http://search.eb.com/eb/article-32320
Comer, R., J., (4th ed.). (2007). Fundamentals of abnormal psychology.
New York: Worth Publishers.
Klein, S. B. & Thorne, B. M. (2007). Biological psychology. New York, NY:
Worth Publishers
Torrey, E. F., Yolken, R. H. (2003). Toxoplasma gondii and schiophrenia.
Emerging Infectious Diseases, 9, 1375-1380.