Transcript Biological Explanations and Therapies for Schizophrenia

Biological Explanations and
Therapies for Schizophrenia
Biological Explanations for
Schizophrenia
Genetic Factors
Brain Structure (Neuronatomy)
The Dopamine Hypothesis
(Chemical Imbalances)
Genetic Factors
According to Gottesman (1991) schizophrenia is an inherited illness caused by a faulty gene.
Concordance Rate (CR) – the likelihood of somebody developing schizophrenia
Twin Studies
Gottesman looked at mozygotic (MZ) (identical) and dyzagotic (DZ) (non-identical) twins. He
found a CR of 48% in MZ twins and CR of 17% in DZ twins.
Why are these figures so important? Although they show a relationship between
schizophrenia and genetics, this relationship is only suggested. As of yet there is no research
to suggest that there is one single faulty gene to cause schizophrenia. There exist many other
explanations as to why this illness develops.
Identical twins share 100% of their genes, therefore, according to the theory, there should be
a 100% CR in MZ twins. Likewise, there should be a 50% in DZ twins. The fact that this is not
would suggest that there are other contributing factors to schizophrenia (the nurture of the
individual)
In criticism of this however, the same CR was found in cases where the twins were brought
up apart.
A more current study taking place in 2002 (Cardno) found a significantly smaller CR, with only
CR of 26.5% in MZ and no CR in DZ twins.
Genetic Factors
Adoption Studies
Tienari looked at 155 adopted children in Findland. For
children which schizophrenic biological mothers there
was a 10% CR. For those without schizophrenic
mothers there was a mere 1%.
Family Studies
Gottesman discovered that if both of your parents
were schizophrenic you would have a CR of 46%. The
closer the relative, the higher CR rate.
Could you make a list of some good
AO2 points concerning adoption
and family studies? Try to think of
some positive as well as negative
arguments...
Brain Structure (Neuronatomy)
Anderson (1990) looked at CAT scans of DZ twins, one
diagnosed with schizophrenia, the other not. His
findings were extraordinary. The brain structure of the
schizophrenic sibling was significantly different. Their
ventricles were unusually enlarged with cavities.
This research has been supported by a larger study
(Crook 2000) including 90 CAT scans who showed
similar findings.
There are of course possible reasons for having
enlarged ventricles... (could have medication caused
this abnormality?)
The Dopamine Theory
(Chemical Imbalances)
This theory suggest that dopamine is the key
to developing schizophrenia. High levels of
dopamine lead to positive symptoms of
schizophrenia, which could be triggered by an
over reactive sensory nervous system.
Low levels of dopamine cause symptoms
found in patients with Parkinson’s Disease,
shaking of the limbs.
The Dopamine Theory
This theory has been scientifically tested. Patients
who were given L-dopa or amphetamine (both
hormones which inhibits dopamine production)
showed progressively worse symptoms (Davidson
1996).
Treating patients with clozapine or
phenothiazines meditated this effect.
Although this strong empirical evidence, we
cannot be sure if the high levels of dopamine are
the cause or the effect of the illness.
Biological Therapies for Treating
Schizophrenia
Antipsychotic Medication
- Conventional Drugs
- Atypical Drugs
Electroconvulsive Therapy (ECT)
Conventional Antipsychotics
Conventional drugs aim to treat the positive symptoms of schizophrenia. They are also called neuroleptic drugs. There are
many different types of neuroleptic drugs however you only need to know one example of this.
Phenothiazines block dopamine passing at the synapses of
neurotransmitters. They bind to the dopamine receptors but without
stimulating them. The drug lowers levels of positive symptoms of
schizophrenia. As the treatment is only temporary, the effects soon wear off
and the symptoms return.
• The treatment does not treat the illness as it only tackles the symptoms
• Low levels of dopamine have been linked to Tardive Dyskinesia (involuntary shaking of
the limbs) which is a symptom for Parkinson’s Disease
• Davies et al (1980) found that although conventional antipsychotic medication did make
a difference, they were only effective for patients who lived in hostile and negative home
environments
• There are many side effects; 30% of patients get Tardive Dyskinesia, with 75% of cases
being irreversible
• Prescribing medication gives patients an excuse to search for a real treatment. It
prevents them from thinking about possible stressors which may cause the illness (i.e.
Family history or circumstances)
Atypical Antipsychotics
Atypical antipsychotics also treat the dopamine, but they also treat the
serotonin and other chemicals in the brain which are thought to cause
schizophrenic symptoms. Such antipsychotics are clozapine. Clozapine
temporarily occupies the D2 receptors. After the medication has worn off
there is a rapid flow of dopamine. This characteristic is thought to be the
cause of lower levels of side effects (such as Tardive Dyskinesia).
• There was much speculation about these drugs when they first appeared. However
there is empirical evidence to suggest that these drugs are little to no different in effect
for treating the symptoms of schizophrenia (Leucht et al 1999)
• Following this criticism is all of that which comes with medication and drug treatment
• As there are fewer side effects of atypical drugs it may encourage the patient to continue
taking the medication as they effectively feel better
Electroconvulsive Therapy (ECT)
You will only need to know a little about ECT as most research in this area is conduced on patients
suffering with depression.
Electroconvulsive Therapy (ECT) is a short medical procedure which involves passing
a short electric shock through the brain in order to ‘restart’ it and it’s functions. Prior
to the procedure a patient is made unconscious and undergoes paralysis. The shock
of 0.6 AMPS lasts for half a second, causing a minute long seizure of the nervous
system.
Initial research (Karagulla, 1950) into the effects of ECT on patients with
schizophrenia was disappointing, as it showed a lower recovery rate compared to
those who did not receive the treatment.
Some of the side effects of ECT is memory dysfunction, brain damage and in some
cases, even death!
Ethical issues? Patients who suffer from schizophrenia may be willing to try
anything in order to cure their illness if they feel scared, under constant threat and
maybe even suicidal. Although a patient may give informed consent they may not
be necessarily fully aware of what they are signing up for!
There is very little evaluation on this PowerPoint. It is now up to
you to go back and add as many evaluative points as you can
possibly think of. After you have exhausted all of your knowledge
you can move on to using the internet or some books to see if
you can find anything you may have missed.
Remember, you have ALOT of information you need to know for your exam so
only stick to the basics. Revise all of your AO1 intensively. Of course, revise your
AO2 too however you must feel comfortable enough to be able to do this with
any theory or study that is laid before you. You are already a psychologists.
Work with it.