Schizophrenia : Biological therapies for Schizophrenia - Drug Therapy

Question 1

What are the two types of antipsychotics used to treat SZ?

Answer 1

Typical and atypical

Question 2

How are antipsychotics dopamine antagonstics?

Answer 2

They bind to complementary dopamine receptors on the postsynaptic membrane, thus preventing dopamine molecules from binding to these sites. The result is an inhibitory effect, where there is a lower rate of action potential generation in the postsynaptic membranes, and so returns neurotransmission to a normal level.

Question 3

What are antipsychotics typically describes as, why?

Answer 3

‘First generation’ because these were the drugs historically prescribed to treat SZ patients.

Question 4

What is the main example of a typical antipsychotic?

Answer 4

Chlorpromazine - it is particularly favoured in psychiatric institutions due to its calming and sedative effects, due to acting upon histame receptors in addition to dopamine receptors

Question 5

What are atypical antipsychotics described as?

Answer 5

‘Second generation’ because they were developed to add to the effectiveness of first generation medications, and also alleviate the serious side effects associated with such drugs.

Question 6

How do atypical antipsychotics work?

Answer 6

They work in the same way as typical antipsychotics, but also target other neurotransmitter receptors on postsynaptic membranes, in line with more modern research.

For example, Clozapine targets serotonin and glutamate receptors, whilst Risperidone acts on dopamine and serotonin receptors.

Question 7

What is the key advantage of Clozapine?

Answer 7

The improvements in cognitive functioning and mood which patients experience when taking it. This is particularly useful considering that SZ has a 50% comorbidity rate with depression.

Question 8

What is the key advantage of Risperidone?

Answer 8

Smaller doses are required because it acts more strongly on dopamine receptors compared to Clozapine, and so would be particularly suited to patients who do not suffer from depression but have a previous history of blood-related illnesses.

Question 9

What are the limitations of drug therapies

Answer 9

• The development of antipsychotics was mainly based upon the dopamine hypothesis, and so their use depends on this theory For example, if antipsychotics appear to alleviate symptoms by reducing the action of dopamine, this makes sense considering the original dopamine hypothesis i,e hyperdomapinergia in the subcortex. However this action is not in line with the revised version of the dopamine hypothesis, which suggests that abnormally low levels of dopamine in the cortex are responsible for symptoms . Therefore, a further reduction in dopamine levels should make symptoms worse, and not better. This paradox has caused some to question the validity of the use of antipsychotics, as well as the accuracy of the dopamine hypothesis as an ex.
• Serious side effects =Short term include agitation and weight gain. Long term include tardive dyskinesia and neuroleptic malignant syndrome (NMS) which is characterised by fever, altered mental states and muscle rigidity. A cost-benefit analysis should be carried out to consider whether the benefit of symptom reduction outweighs the cost of side effects for each specific patient.

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Question 10

Strengths of drug therapies

Answer 10

+ Easy to take - not disruptive of the day

Question 11

What are typical antipsychotics used for?

Answer 11

Are used primarily to combat positive symptoms of sz which are a product of an overactive dopamine system.

Question 12

What are atypical antipsychotics used for?

Answer 12

Combats positive symptoms but has some beneficial effects on negative symptoms as well

Question 13

What is a flaw of typical antipsychotics?

Answer 13

In order to block the D2 receptors required for reducing symptoms, other D2 receptors in the brain must also be blocked which can lead to undesirable side effects. This problem has been addressed by the development of atypical drugs.

Question 14

Explain support for the effectiveness of antipsychotics

Answer 14

Support comes from studies that have compared relapse rates for antipsychotics and placebos. Leucht carried out a metaanalysis of 65 studies involving nealry 6,000 patients . All patients had been stabilised on either typical or atypical antipsychotics . Some of these patients had been taken off their medication and given placebos instead. The rest remained on their current antipsychotic. Within 12 months, 64% of those who had been given placebo relapsed, compared to 27% who stayed on their antipsychotics.

Question 15

Explain the extrapyramidal side effects that can occur from taking typical antipsychotics

Answer 15

Taking typical antipsychotic drugs can lead to movement problems for the pateint. These are called extrapyramidal side effects because they impact the extrapyramidal area of the brain which helps control motor activity . More than half of the patients taking typical antipsychotics experience Parkisonian symptoms . Tardive dyskinesia i.e involuntary movements of the tongue, face and jaw can occur after taking the drugs for an extended period of time.

Question 16

What are the ethical issues with typical antipsychotics?

Answer 16

Critics argue that if side effects, deaths, and psychosocial consequences were taken into account, a cost benefit of its advantages would probably be negative. Recently in the US, a large out’of’court settlement was awarded to a tardive dyskinesia sufferer on the basis of a HUmans RIght Act whcih says that no one shall be subjected to inhuman or degrading treatment or punishment.

Question 17

What are the advantages of atypical over typical antipsychotics?

Answer 17

A key advantage of atypical is the patients experience fewer side effects . More newly developed atypical antipsychotics are less likely to produce the extrapyramidal effects typically found with typical antipsychotics -therefore patients are more likely to continue with their treatment and therefore are more likely to see a reduction in their symptoms.

Question 18

Are atypical antipsychotics better?

Answer 18

Crossley et al carried out a meta-analysis of 15 studies to examine the efficacy and side effects of atypical versus typical antipsychotics. They found no significant differences between the drugs in terms of their effect on symptoms but did note differences in the type of side effects experienced. Patients on atypical antipsychotics gained more weight than those on typicals , whereas those on typicals experienced more extrapyramidal side effects . They concluded there was no evidence for differences in efficacy but there was a clear difference in side effects experienced.