Conventional/typical antipsychotics - combat positive symptoms
- reduce the effects of dopamine and so reduce the symptoms of schizophrenia
- dopamine antagonists -> they bind to dopamine receptors (particularly the D2 receptors) but do not stimulate them, thus blocking their action.
- by reducing stimulation of the dopamine system in the brain, antipsychotic drugs (e.g. chlorpromazine) can eliminate the hallucinations and delusions experienced by people with schizophrenia.
- Davis et al (1980) -> compared relapse rates with those on a placebo
- found a significant difference in terms of relapse rates between treatment and placebo in every study reviewed, thus demonstrating the therapeutic effectiveness of these drugs.
- However, a more recent analysis of that study by Ross and Read has suggested that its results were misleading: as all those studied, including those who took placebos, were on antipsychotics before this study began, it was, rather than a study comparing treat to non-treatment, a comparison between continued treatment and withdrawn treatment.
- Ross and Read suggest a significant proportion of the relapses in the placebo group can be explained by these withdrawal symptoms, leaving the conclusions drawn by Davis discredited.
- side effects -> development of tardive dyskinesia- uncontrollable movements of the lips, tongue, face, hands and feet- in 30% of patients taking typical antipsychotics, with only 25% of these cases treatable.
- some suggest that given this side effect, administration of these drugs is unethical, and defies articles regarding harmless treatment in the Human Right Acts 1988.
- Therefore, physicians prescribe conventional antipsychotics less frequently than they used to because of the potential for serious side effects. Instead, physicians often preferentially prescribe a newer family of antipsychotic medications, known as atypical antipsychotics.
- Atypical antipsychotics also act on the dopamine system, but are thought to block serotonin receptors in the brain too.
- Kapur and Remington however suggest that these drugs do not involve serotonin or other neurotransmitters, but only the dopamine system and the D2 receptors in particular.
- They help by only temporarily occupying the D2 receptors and then rapidly dissociating to allow normal dopamine transmission.
- It is this characteristic of atypical antipsychotics…