Lesson 4 – Biological Treatments for Schizophrenia Flashcards
What is the most common treatment for schizophrenia
The most common treatment for SZ is drugs – specifically antipsychotic drugs.
How are antipsychotic drugs delivered to the patient
These drugs can be taken in the form of tablets or syrup or even injections. Injections tend to be given to those patients who are at risk of not taking their medication or don’t take it properly. Injections would be given every 2 – 4 weeks.
What are the types of antipsychotic drugs
Typical (traditional or first generation) antipsychotics and
Atypical (second generation) antipsychotics
What are typical antipsychotics
These drugs are dopamine antagonists and work by reducing the effects of dopamine and thus reduce the symptoms of SZ. These drugs therefore bind to but do not stimulate dopamine receptors (particularly the D2 receptors in the mesolimbic dopamine pathway), thus blocking their action. This in turn will reduce the positive symptoms of SZ.
What is an example of a typical antipsychotic
Chlorpromazine
General effects of typical antipsychotics
Typical antipsychotics have a strong link to the dopamine hypothesis explanation of SZ whereby this hypothesis suggests that schizophrenic symptoms are due to high levels of dopamine.
Typical antipsychotics are dopamine antagonists in that they bind to but do not stimulate dopamine receptors. In other words, they block the dopamine receptors in the synapses of the brain, reducing the actions of dopamine.
How can Chlorpromazine be delivered
This drug can be taken as a tablet, syrup or injection.
Effects of Chlorpromazine
When the patient would first take Chlorpromazine, dopamine levels would build up but then the production of dopamine would reduce.
Therefore, with reference to the dopamine hypothesis explanation, this antagonist drug would normalize the dopamine production and transmission – this in turn would then reduce the symptoms of SZ such as hallucinations.
Dosage of Chlorpromazine
The maximum dosage for the tablet would be 1000mg. Of course, when given first, the dosage would be much smaller but gradually increased from about 400mg to 800mg.
What are examples of atypical antipsychotics
Clozapine and Risperidone
General effects of atypical antipsychotics
These drugs work like typical antipsychotics by blocking D2 receptors. However, they only temporarily occupy the D2 receptors and then rapidly dissociate to allow normal dopamine transmission – it is this rapid dissociation that is thought to be responsible for the lower levels of side effects.
How can Clozapine be delivered
Because of its fatal side effects, clozapine is not available as an injection but only in syrup or tablet.
Effects of Clozapine
Clozapine works by binding to dopamine receptors but in addition, acts on serotonin and glutamate receptors. By the drug working on other neurotransmitters, this helps to reduce depression and anxiety and improve cognitive functioning. Because clozapine does improve mood, it is generally given to patients who are at high risk of suicide. This is important as research has shown that between 30-50% of patients with SZ are likely to attempt suicide. However, due to a number of patients dying from a blood condition called agranulocytosis after taking clozapine, it was withdrawn. Even today, clozapine is still used as an alternative. However, patients are given regular blood tests to make sure that they don’t have agranulocytosis.
Dosage of Clozapine
The dosage given to patients is between 300 – 450 mg per day – much lower than chlorpromazine.
How can Risperidone be delivered
Risperidone can be taken as syrup, tablets or injection.
Effects of Risperidone
Risperidone like clozapine works by binding to dopamine receptors but works better in binding to dopamine receptors than clozapine leading to less side effects. As a result, much smaller doses are required of risperidone.
Evidence also suggests that this leads to fewer side effects than most other antipsychotics.
Dosage of Risperidone
Patients are given a dose of about 4-8mg and up to a maximum of 12mg.
Strengths of drug therapy to treat schizophrenia
There is research evidence to support the moderate effectiveness of typical antipsychotic drugs in treating SZ. For example: Thornley et al (2003) compared the use of chlorpromazine (typical antipsychotics) with a placebo. Data from 13 trials with a total of 1121 pps showed that chlorpromazine was associated with reduced symptoms and better overall functioning. Furthermore, data from three trials with a total of 512 pps showed that relapse rate was also lower when chlorpromazine was taken. This study this shows that typical antipsychotics were effective in reducing the symptoms of SZ compared to a placebo showing that drug therapy is appropriate in treating SZ.
There is also research evidence to support the appropriateness of atypical antipsychotics. In a review by Meltzer (2012), he concluded that Clozapine (atypical antipsychotics) is more effective than typical antipsychotics and other atypical antipsychotics in treating SZ. In fact Clozapine was seen as effective in 30-50% of cases where typical antipsychotics had failed. This study shows that use of clozapine as a treatment for SZ is a very appropriate drug as Meltzer clearly showed especially when other drugs failed!
Leucht et al. (2012) carried out a meta-analysis of 65 studies, published between 1959 and 2011, and involving nearly 6000 patients. Some patients were taken off their antipsychotic medication and given placebos instead. Within 12 months, 64% of those patients who had been given the placebo relapsed whereas only 27% relapsed when on antipsychotic medication. The results of this study clearly show that antipsychotic medication is both effective and appropriate in preventing a schizophrenic patient from relapsing.
Weaknesses of drug therapy to treat schizophrenia
The biggest weakness of drug therapy in treating SZ is the serious side effects ranging from mild ones to being fatal. For typical antipsychotics, the side effects include: dizziness, agitation, sleepiness, stiff jaw, weight gain and itchy skin. Whereas atypical antipsychotics were developed to overcome these side effects. However, side effects do exist for atypical antipsychotics such as Clozapine thus regular blood tests need to be taken of the patients to test for early signs of agranulocytosis (a rare blood condition where the production of white blood cells is prevented – leads to problems with immunity)
There are problems with the evidence for the effectiveness of drugs and this has been challenged by Healy (2012) has suggested that some successful drug trials have had their data published on multiple occasions thus exaggerating the effectiveness. Also because antipsychotics have powerful calming effects, it seems as though the drugs are successful. However, this does not really show how much the drugs actually reduce the symptoms. Furthermore, most published studies only assess the short-term benefits of drug therapy rather than the long term benefits especially for those patients who have stopped taking the drugs.
There is of course ethical issues related to using drug therapy for SZ. The most profound ethical issue would be consent – e.g. due to the fact that schizophrenia is a psychotic disorder, patients may not be in the right frame of mind to give fully informed consent in taking the drugs and because the drugs do have such severe side effects, one would question the extent of the harm (both physical and mental) and whether the effects of the drugs were reversible especially with side effects such as NMS and tardive dyskinesia
