Biological Explanations and Therapies for Schizophrenia

Biological Explanations for Schizophrenia

Genetic Factors

Brain Structure (Neuronatomy)

The Dopamine Hypothesis (Chemical Imbalances)

Genetic FactorsAccording to Gottesman (1991) schizophrenia is an inherited illness caused by a faulty gene.

Concordance Rate (CR) – the likelihood of somebody developing schizophrenia

Twin StudiesGottesman 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 StudiesTienari 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 StudiesGottesman 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 AntipsychoticsConventional 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 AntipsychoticsAtypical 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.