biological treatments for schizophrenia

Question 1

what are antipsychotics?

Answer 1

drugs used to reduce the intensity of symptoms, particularly positive symptoms.

Question 2

what are typical antipsychotics? give one example.

Answer 2

first generation drugs, used since the 1950’s which work as dopamine antagonists
- chlorpromazine

Question 3

what are atypical psychotics? give 2 examples.

Answer 3

developed after the typical type: they target dopamine and serotonin
- clozapine and risperidone.

Question 4

what created the symptoms of schizophrenia in healthy people and how?

Answer 4

amphetamines as they affect the dopamine system

Question 5

what are the two types of antipsychotic drugs?

Answer 5

conventional and atypical.

Question 6

what are conventional drugs?

Answer 6

used to reduce the effects of dopamine and therefore the symptoms of schizophrenia. they are dopamine antagonists and so bind to dopamine receptors but do not stimulate them, so they block their action

Question 7

what are conventional drugs available as and what is the dosage?

Answer 7

tablets, injections or syrups. oral doss are usually between 400mg-800mg up to a maximum of 1000mg

Question 8

chlorpromazine has a what effect?

Answer 8

sedative. it is often used to calm patients down through syrup if they are very anxious when first admitted to hospitals.

Question 9

what how do conventional antipsychotic drugs work?

Answer 9

• neurons transmit signals electrically along their axons
• the synapses transmit the signals chemically to the next neuron
• when an action potential reaches the axon terminal, vesicles release neurotransmitters into the synaptic cleft which bind to receptors on the post-synaptic neuron and activate them.
  -enzymes are released to break down the neurotransmitter and excess transmitter is taken back up to the pre-synaptic neuron (re-uptake)
  -neuroleptics bind to dopamine receptors without activating them
  -therefore, block activity of the dopamine

Question 10

how do dopamine antagonists work?

Answer 10

• bind the D1-like and D-2 like dopamine receptors
  -by doing so, they activate the dopamine receptors in the same way that dopamine does, meaning that dopamine antagonists can help relieve symptoms that occur due to low dopamine.

Question 11

how do atypical antipsychotics work?

Answer 11

• drugs such as clozapine also work on the dopamine system, but in addition have an effect on the serotonin system.
• believed to reduced both positive and negative symptoms.

Question 12

Kapur and Remington (2001)

Answer 12

argue that clozapine works by affecting D2 dopamine receptors by temporarily occupying them on the post-synaptic neuron, and then quickly dissociating which allows for normal dopamine transmission.

Question 13

what effect may atypical antipsychotics have?

Answer 13

as it works on serotonin, it is believed to have mood enhancing effects so it is sometimes prescribed when there are high risks of suicide.

Question 14

why are atypical antipsychotics used with caution today?

Answer 14

withdrawn due to deaths from agranulocytosis (severe reduction in white blood cells) and it is not available as an injection because of its serious side effects.

Question 15

what are the typical dosages of atypical antipsychotics such as clozapine?

Answer 15

300-450mg each day.

Question 16

why was risperidone developed? what is the dosage?

Answer 16

• developed in the 90’s to be as effective as clozapine but without the side effects
  -available as syrups, injections and tablets
  -small dose given gradually rising to 4-8mg per day, but no more than 12mg as it is more effective in samaller doses as it binds more strongly to dopamine receptors.

Question 17

effectiveness evaluation (Davis et al 1980)

Answer 17

conducted a review which showed a significant difference in patients receiving the conventional antipsychotics in every study, supporting their effectiveness.

Question 18

Thorley et al (2003)

Answer 18

• reviewed studies comparing chlorpromazine to controls where patients received a placebo
• data from 13 trials with over 1000 patients showed chlorpromazine was associated with better overall functioning and reduced severity of symptoms.
• from 3 of the trials and 512 patients, relapse rate was also lower when chlorpromazine was taken.

Question 19

David Healy (2012)

Answer 19

suggested serious flaws with evidence for effectiveness. for example, most studies are of short-term effects only and some successful cases have had their studies published multiple times, exaggerating the size of the evidence base for positive effects.

Question 20

what are the side effects of typical antipsychotics such as chlorpromazine?

Answer 20

dizziness/sleepiness, agitation, itchy skin + weight gain and stiff jaw.

Question 21

long term use of conventional antipsychotics and its appropriateness (side effects)

Answer 21

• about 30% develop tardive dyskenisia (uncontrollable movements of tongue, lips, face, hands and feet caused by supersensitivity.
• irreversible in about 75% of patients (Hill 1986)

Question 22

long term use of conventional antipsychotics (most serious side effect)

Answer 22

• neuroleptic malignant syndrome (NMS) which lads to high temperature, delirium, coma and even death
• the drug blocks dopamine action in the hypothalamus, which is associated with the control of several body systems, as such may cause these side effects to occur
  -however, it is rare now due to such low doses given to patients (0.1%-2%)

Question 23

effectiveness and antipsychotics (Meltzer (2012)

Answer 23

• found clozapine to be more effective than typical antipsychotics and other atypical antipsychotics, and that it was effective in 30-50% of treatment resistant cases where typical antipsychotics have failed
• but overall, drug treatments do not work for 30% of patients

Question 24

Leucht et al (1999)

Answer 24

conducted a meta-analysis and found a moderate effect, where two of the new drugs were slightly more effective and the other two were no more effective, compared to the older conventional antipsychotics and were true of both positive and negative symptoms.

Question 25

issues with the dopamine hypothesis itself

Answer 25

• the drug treatments are based on the idea that we have understood dopamine activity correctly - namely that elevated levels are found in the subcortex and drugs reduce this. However, some parts of the brain contain dopamine levels which are too low.
• if this is the case then how dopamine antagonists work is unclear.

Question 26

three general strengths of drug therapies?

Answer 26

• enabled many schizophrenics to live in the community rather than being institutionalised
• more effective than a placebo
• relatively cheap at point of delivery.

Question 27

three issues with drug therapies as a whole?

Answer 27

• however, drug therapies can take up to 6 months to work; drugs treat the symptoms but not the cause and some patients do not respond to drug treatments
• when patients are prescribed medication, it reinforces the view that there really is something wrong with them which may make it less likely for the patient to consider causes of their problems and solutions (Ross and Read 2004)
  -are meds given for the benefits of the patient, or the staff who have to deal with them ‘chemical strait jacket’