Biological therapies for schizophrenia

Antipsychotics

Drugs used to reduce the intensity of symptoms, in particular the positive symptoms of psychotic conditions like schizophrenia

Typical antipsychotics

The first generation of drugs for schizophrenia and other psychotic conditions, used since the 1950s.

Work as dopamine antagonists.

E.g. chlorpromazine

Atypical antipsychotics

Drugs for schizophrenia developed after typical antipsychotics.

Target a range of neurotransmitters like dopamine and serotonin.

E.g. clozapine and risperidone

Typical - Dopamine antagonists

Strong association between the use of antipsychotics and the dopamine hypothesis.

They work as antagonists in the dopamine system.

Antagonists - Chemical which reduce the action of a neurotransmitter.

Dopamine antagonists - Block dopamine receptors in the synapses of the brain and reduces the action of dopamine.

When someone starts taking chlorpromazine, dopamine levels build up but then the production is reduced. According to the dopamine hypothesis of schizophrenia the dopamine-antagonist effect stabilises neurotransmission in key areas of the brain and reduces hallucinations

Typical - Sedation effect

Chlorpromazine is an effective sedative.

Believed to be related to its effect on histamine receptors but it is not fully understood how this leads to sedation.

Chlorpromazine can calm people with conditions that aren’t just schizophrenia as well as people in hospitals who are very anxious.

Atypical - Clozapine

Binds to dopamine receptors in the same way that chlorpromazine does, but also acts on serotonin and glutamate receptors.

This action helps improve mood and reduce depression and anxiety in patients and it may improve cognitive functioning.

Mood-enhancing effects of clozapine mean that it is sometimes prescribed when an individual is considered at high risk of su!cide. Important as a large number of people with schizophrenia attempt su!cide at some point in their lives

Atypical - Risperidone

Can be taken in the form of tablets or as an injection.

Binds to dopamine and serotonin receptors. Binds more strongly to dopamine receptors than clozapine and is effective in much smaller doses than most antipsychotics.

There is evidence to suggest that this leads to fewer side effects than other antipsychotics.

W Evidence to support effectiveness

Thornley

Meltzer

Reviewed studies that compared the effects of chlorpromazine with a control condition.

13 trials with a total of 1121 participants - chlorpromazine was associated with better overall functioning and reduced symptom severity compared to a placebo.

Found that clozapine is more effective than typical antipsychotics and other atypical antipsychotics. Effective in 30-50% of treatment-resistant cases where typical antipsychotics would’ve failed.

Suggests that antipsychotics work to treat schizophrenia.

W Side effects

Typical antipsychotics are associated with dizziness, agitation, sleepiness, stiff jaw and itchy skin. Long-term use can cause tardive dyskinesia - dopamine supersensitivity and includes involuntary face movements.

Serious side effect of typical antipsychotics - Neuroleptic Malignant Syndrome - When the drug blocks dopamine action in the hypothalamus and results in a high temperature, delirium and coma, can be fatal.

Suggests that antipsychotics can do harm as well as good and some people may want to avoid the treatment.

W Good outcomes in countries which don’t use them

People are given antipsychotics when they first develop psychosis.

In Finland patients are involved in treatment choices and may or may not take antipsychotics.

If antipsychotics were necessary then the outcomes there would be poor as they don’t choose it.

Bergström and Gauffin found that people who did not start taking antipsychotics on diagnosis were less likely to receive treatment or disability benefits 5 years later.

Suggests that some people do not need antipsychotics and appear better off without them