drug therapy

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  Drugs that are effective in treating forms of psychotic illness, such as schizophrenia are called antipsychotics. Antipsychotics are usually recommended as the initial treatment for the symptoms of schizophrenia, after which clinicians tend to use a combination of medication and psychological therapy. All antipsychotics work by reducing dopaminergic transmission, i.e. reducing the action of the neurotransmitter dopamine in areas of the brain associated with the symptoms of schizophrenia.
• . Typical antipsychotics (chlorpromazine) are used for the positive symptoms of schizophrenia such as hallucinations (product of an overactive dopamine system).

  The atypical antipsychotic drugs (clozapine) also combat these positive symptoms, but also claims that they have some beneficial effects on negative symptoms. Typical antipsychotics (or 'first-generation') were developed in the 1950s. The basic mechanism is to reduce the effects of dopamine, so reduce the symptoms of schizophrenia.
• Typical antipsychotics are dopamine antagonists, they bind to but don’t stimulate dopamine receptors (particularly D2 receptors in the mesolimbic dopamine pathway), so blocking their action. By reducing stimulation of the dopamine system in the mesolimbic pathway, drugs like chlorpromazine eliminate the hallucinations and delusions after a few days. Kapur estimates that between 60% and 75% of D2 receptors in the mesolimbic dopamine pathway must be blocked to be effective. But to do this, a similar number of D, receptors in other areas of the brain must also be blocked, leading to side effects.
• There are several dopamine pathways in the brain, and it appears that blocking dopamine receptors in only one of them is useful.  Atypical antipsychotic (or 'second-generation') carry a lower risk of side effects and have a beneficial effect on negative symptoms and cognitive impairment. They also act on the dopamine system by blocking D2 receptors. But only temporarily occupy the D2 receptors and then rapidly dissociate to allow normal dopamine transmission. The rapid dissociation is thought to be responsible for the lower levels of side effects compared to antipsychotics.
• Because atypical antipsychotics have very little effect on the dopamine systems that control movement, they tend not to cause the movement problems found with the typical antipsychotics. Atypical antipsychotics have a stronger affinity for serotonin receptors (particularly the 5-HT receptors) and a lower affinity for D2 receptors. It is this characteristic that explains the different effects of atypical compared to typical antipsychotics.
• Support for drug therapy comes from studies using placebos.

  Leucht (2012) carried out a meta analysis of 65 studies between 1959 and 2012, involving around 6000 patients. Some of the patients were taken off the medication and given a placebo instead. Within 12 months 64% of the patients on placebo had relapsed compared to 27% who stayed on the drug.

  This study demonstrates how the medication does help compared to no medication.
• This however could be seen as an ethical issue.

  Patients who believe they are taking medication, but been given a placebo without consent can bring problems to the patient due to the symptoms not being controlled. Especially with schizophrenia, they may not be aware of these symptoms returning.

  This highlights a problem with a study, however it does bring a benefit of knowing how affective the drug treatment is.
• An issue with drug therapy are the side effects experienced.

  The most common side effect are the parkinsonian and related symptoms. More than half of the patients taking typical antipsychotics experience these symptoms. When the drugs are taken for an extended period, tardive dyskinesia can occur which is the involuntary movement of the face, tongue and jaw.

  This side effects have such a bad impact, other medication is taken to control them or even stopping medication completely.
• However atypical antipsychotics are claimed to have more advantages than typical antipsychotics in relation to side effects.

  Atypical antipsychotics, particularly new developed drugs, are less likely to produce the extrapyramidal effects commonly found with typical antipsychotics.

  As a result, patients are more likely to continue their medication, so symptoms can reduce.