biological treatment for schizophrenia Flashcards
intro
Drugs for the most disturbing forms of psychotic illness are called antipsychotics.
All antipsychotics work as dopamine antagonists - They reduce the action of dopamine in areas of the brain associated with symptoms of schizophrenia
• Typical / Conventional
• Atypical
typical antipsychotics
Typical antipsychotics are first generation antipsychotics.
An example of a typical
antipsychotic is Chlorpromazine
• Work by binding to dopamine receptors, without stimulating them.
• Reduction of positive symptoms
• Led to the development of the dopamine hypothesis
problem-typical
Kapur et al. (2000) estimated that between 60% and 70% of D, receptors in the mesolimbic dopamine pathway must be blocked for these drugs to be affective.
• A similar number of D2 receptors in other areas of the brain must also be blocked
→ Undesirable side-effects
typical side effects
One example of many, is the development of extrapyramidal side effect (drugs affect dopamine pathways inextrapyramidal areas of brain responsible for motor activity) such as tardive dyskinesia.
• Involuntary movement of the tongue face and jaw.
-Drugs affect the extra pyramidal area of the brain, which helps to control motor activity.
typical-other effects
As well as being an antipsychotic, chlorpromazine is also an effective sedative.
• Often used to calm patients down.
-Often used when patients are first admitted to hospital.
Atypical antipsychotics
Second generation antipsychotic,
e.g Clozapine, designed to maintain effectiveness, whilst reducing side-effects.
Only temporarily occupy DA receptors before rapidly dissociating and allowing normal dopamine transmission
→ Less extra pyramidal side effects.
other effects atypical
Additionally, atypical antipsychotics don’t just act on dopamine receptors, but also on serotonin and glutamate receptors.
• This means that they can effect both positive and negative symptoms
• Improving mood and cognitive functioning
• Reducing anxiety and depression
• Often provided to patients at risk of suicide.
strength-evidence for effectiveness
Thornley et al. (2003)
• Data from 13 trials with 1121 participants showed that chlorpromazine was associated with better overall functioning and reduced symptom severity when compared to the placebo.
Meltzer (2012)
• Clozapine is more effective than typical antipsychotics and other atypical antipsychotics, and that it is effective in 30-50% of treatment-resistant cases where typical antipsychotics have failed.
limitation-problem with research
Healy (2012) has suggested that there are serious flaws with evidence for effectiveness.
• For example most studies are of short-term effects only and some successful trials have had their data published multiple times.
• Powerful calming affect, make it easy to demonstrate that they have some positive affect on people experiencing symptoms of schizophrenia this is not the same as saying they really reduce the severity of psychosis.
→ This means that the evidence base for antipsychotic effectiveness is less impressive than it first appears.
limitation-serious side effects
Typical antipsychotics are associated with a range of side-effects
• Dizziness, agitation, sleepiness, stiff jaw, weight gain and itchy skin.
• Long-term use can result in Tardive dyskinesia.
The most serious side-effects of antipsychotics is neuroleptic malignant syndrome.
-NS results in high temperature, delirium and coma, and can be fatal.
Individuals to experience these may avoid such treatments, which makes the treatment ineffective.
limitation-the chemical cosh
The use of antipsychotics poses a bit of a moral dilemma.
• They calm patients distressed by hallucinations and delusions and they allow patients to engage with other treatments.
• It is believed that antipsychotics have been used in hospital situations to calm people with schizophrenia and make them easier for staff to work with.
• Drugs can be said to be dehumanising as they take away individual personal responsibility and control when they may not have consented to treatment.
6 marker
Biological treatments for schizophrenia focus on the use of dopamine antagonists called antipsychotics.
The first generation of these drugs were known as typical antipsychotics and work by binding to dopamine receptors on the postsynaptic neuron without stimulating them, thereby reducing dopamine activity in areas of the brain associated with schizophrenia and reducing the occurrence of positive symptoms.
In order for this to be effective 60-70% of dopamine receptors across the entire brain must be blocked (Kapur, 2000), which can result in unpleasant extrapyramidal side-effects.
This led to the development of atypical antipsychotics, which were designed to maintain the effectiveness of typical antipsychotics, whilst reducing the side-effects. These drugs also work by blocking dopamine receptors, however they only do so temporarily before disassociating and allowing normal transmission to resume.
In addition to the dopamine system, atypical antipsychotics also act on the serotonin and glutamate systems, which means that are effective in improving mood and cognitive functions, whilst also reducing anxiety and depression.
This is important, as it means that atypical antipsychotics can be effective in addressing negative symptoms as well as positive ones.
AO1 book
Typical antipsychotics have been around since the 1950s and include chlorpromazine which can be taken as tablets, syrup or by injection. If taken orally it is administered daily up to a maximum of 1000 mg, although initially doses are much smaller and for most people the dosage is gradually increased to a maximum of 400 to 800 mg. Typical prescribed doses have declined over the last 50 years (Liu and de Haan 2009).
Clozapine Clozapine was developed in the 1960s and first trialled in the early 1970s. It was withdrawn for a while in the 1970s following the deaths of some patients from a blood condition called agranulocytosis. However, in the 198os, when it was discovered to be more effective than typical antipsychotics, clozapine was remarketed as a treatment for schizophrenia to be used when Other treatments failed. It is still used in this way today, and people taking it have regular blood tests to ensure they are not developing agranulocytosis. Because of its potentially fatal side effects clozapine is not available as an injection. Daily dosage is a little lower than for chlorpromazine, typically 300 to 450 mg a day.
Risperidone Risperidone is a more recently developed atypical antipsychotic, having been around since the 1990s. It was developed in an attempt to produce a drug as effective as clozapine but without its serious side effects. Like chlorpromazine, risperidone can be taken in the form of tablets, syrup or an injection that lasts for around two weeks. In common with other antipsychotics a small dose is initially given and this is built up to a typical daily dose of 4-8 mg and a maximum of 12 mg.
Like clozapine, risperidone is believed to bind to dopamine and serotonin receptors. Risperidone binds more strongly to dopamine receptors than clozapine and is therefore effective in much smaller doses than most antipsychotics. There is some evidence to suggest that this leads to fewer side effects than other antipsychotics.
