Biological therapy

• How do we treat schizophrenia if it has a biological basis?

  • Most common treatment of schizophrenia involves typical or atypical antipsychotic drugs in the form of tablets, syrups, or injections - can be taken long term or short-term
• What are typical antipsychotics? (1950s)

  • Dopamine antagonists block dopamine receptors in the synapses of the brain and have a sedative effect on patients. These bind to but do not stimulate dopamine receptors which blocks their action, therefore normalising neurotransmission in key areas of the brain and reducing positive symptoms
  • An example of chlorpromazine which is often used to calm anxious patients admitted to the hospital, maximum dosage for most people is around 400-800mg
• What are some side effects of typical antipsychotics?

  • Chlorpromazine is an effective sedative, related to its effect on histamine receptors
  • Extrapyramidal symptoms in sudden movement, weight gain, blurred vision
  • Can lead to loss of menstrual periods for women
• What are atypical antipsychotics? (1970s)

  • These still block D2 receptors but only temporarily occupy them, before rapidly dissociating to allow for normal dopamine transmission.
  • They also influence serotonin receptors as well as dopamine, which may contribute to their ability to address both positive and negative symptoms of schizophrenia
• What is clozapine?

  • Developed in the 1960s, binds to dopamine receptors in the same way as chlorpromazine but additionally acts on serotonin and glutamate receptors, believed to help improve mood and cognitive functioning
  • Mood-enhancing effects means it is sometimes prescribed for people at a high risk of suicide
  • During early trials it turned out to be fatal for people with a blood condition called agranulocytosis, however people using it today have regular blood tests to ensure they don't have this
• What is risperidone?

  • More recently developed atypical antipsychotic that binds more strongly dopamine receptors as well as serotonin receptors, and is therefore effective in much smaller doses than most antipsychotics
  • Is evidenced to lead to fewer side effects
  • Typical daily dose is around 4-8mg and lasts for up to 2 weeks
• What are the differences between typical and atypical antipsychotics?

  • Atypical psychotics tend not to affect the dopamine systems that control movement, carrying a lower risk of extrapyramidal side effects
  • Due to blocking serotonin receptors on top of dopamine they can also benefit negative symptoms as well as cognitive impairments
  • Atypicals can be administered through injections making them suitable for treatment-resistant patients
  • Block D2 receptors for a short period of time, typicals block them for longer
• What is one strength of drug therapy for schizophrenia?

  • Research support for effectiveness: Thornley et al. (2003) reviewed studies comparing the effects oh chlorpromazine to placebos -> data from 13 trials concluded that chlorpromazine was associated with better overall functioning and reduced symptom severity
  • Meltzer (2012) concluded that clozapine is effective in 30-50% of treatment-resistant cases where typical antipsychotics failed
  • Suggests that as far as we can tell antipsychotics work
• What is one limitation of drug therapy for schizophrenia?

  • Exaggerated evidence: Healy (2012) has suggested serious flaws with evidence for effectiveness as most studies only cover short-term effects and the successful ones have been published multiple times, showing an exaggeration of positive effects
  • Because they have powerful calming effects it is easy to demonstrate that they have a positive effect yet this does not equate to reducing the overall severity of their symptoms
  • Suggests the effectiveness of drugs may not be what it seems
• What is another limitation of drug therapy?

  • Serious side-effects: include dizziness, itchiness, weight gain, sleepiness, agitation
  • Long-term use can lead to tardive dyskinesia, characterised by involuntary facial movements like lip-smacking due to dopamine supersensitivity
  • Can also lead to neuroleptic malignant syndrome - when the drug blocks dopaminergic activity in the hypothalamus it can result in high temperature, delirium, comas, can even be fatal
  • May lead to individuals avoiding the treatment altogether, limiting its actual effectiveness
• What is another limitation of drug therapy?

  • Mechanisms unclear: our understanding of atypical and typical drugs are based off of the original dopamine hypothesis which claims that positive symptoms are linked to excess DA
  • BUT the updated hypothesis suggests some symptoms are the results of low dopamine in the brain's cortical regions
  • According to our knowledge most antipsychotics shouldn't work as there are contrasting claims, questioning the effectiveness of the treatment if its' mechanisms is ambiguous and unclear