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Biological Treatments of SZ Learning Objectives Drugs – Atypical & Typical Learning Objectives • name the different biological therapies used to treat schizophrenia • explain the action of different drugs used to treat schizophrenia Background • There was no effective treatment for Sz prior to the discovery of dopamine in 1952. • Drugs were developed that had a direct effect on the action of the dopamine neurotransmitter. • Drugs which markedly reduced the symptoms in people who were severely ill became known as antipsychotics. • Anti-psychotics • Antipsychotics are given to treat the most disturbing forms of psychotic illness such as schizophrenia and bipolar disorder. • There are two types of antipsychotic drugs: • 1. Conventional antipsychotics • 2. Atypical antipsychotics Conventional Anti-psychotics • Used primarily to combat the positive symptoms of Sz such as disordered thinking which are products of overactive dopamine systems. • Their basic mechanism is to reduce the amount of dopamine and so reduce the symptoms of Sz. • How do they work? • They work by binding to dopamine receptors (particularly D2 receptors) and thus blocking their action, not stimulating them. • By reducing the stimulation of the dopamine system in the brain, antipsychotic drugs can eliminate the hallucinations and delusions experienced by patients with Sz. • The effectiveness of these dopamine antagonists in reducing the symptoms of Sz is what led to the development of the dopamine hypothesis. • Atypical Anti-psychotic drugs • Developed in the 1990s • Combat the negative as well as the positive symptoms of Sz • As well as acting on the dopamine system they also stimulate serotonin receptors. • In the same way as conventional psychotics they also bind to D2 receptors but rather than permanently block the dopamine action, they temporarily bind to the receptors and then rapidly dissociate to allow normal dopamine transmission. • Evaluation – In terms of effectiveness & appropriateness • Overall positive implication of antipsychotic drugs: • Drug therapy offers more humane & effective treatments than previously available, EG: ECT & Psychosurgery • Rapidly reduce most disturbing symptoms • Aid individuals in living a more normal life Effectiveness of conventional antipsychotics • Davis (1990) – Drugs effective in comparison to placebo in of those reported on – a reduction of apprx 30% relapse rates • Vaughn & Leff (1976) – Found drugs to be effective in only some cases – (where homelife was extreme and unsupportive) • In more supportive home environments, no significant difference between those on antopsychotics and placebo Conventional Antipsychotics evaluation cont’d • Some extreme side effects - · Weight gain, diabetes, sexual dysfunction, insomnia and muscle tremors • 30% of patients experience tardive dyskenesia – uncontrollable movement & shaking of body, limbs & face • Such side effects might explain high drop out rates Atypical drugs – Evaluation • Appear to be effective on both positive and negative symptoms • Leucht (1999) meta-anlaysis - superiority of the atypical drugs compared to conventional drugs was only moderate • Girgis et al (2011) concluded the newer atypical drugs are no more effective and cause only slightly fewer side effects. • Jetse (1999) found a 30% rate of tardive dyskenesia in people taking conventional compared to 5% with atypical antipsychotics General Evaluation & IDA • Placebo comparisons raise ethical issues as such patients will be in a drug withdrawal state which results in overwhelming flooding of dopamine system ( See dog book – pg 169 – Ross & Read 2004) • Drug resistance over time – Drugs don’t work for all • Appears to work best in conjunction with support from home • Cost benefits – Typical anti-psychotic EG: Chloromazine - £10 per year • Atypical anti-psychotic – clozapine - £1500 per year After two decades, it is now clear that antipsychotic drugs do not cure schizophrenia. No other single therapeutic procedure can compete with drug treatment in terms of rapid effectiveness, sustained action, general availability and ease of application. Relapse rates, in general, during withdrawal from psychiatric drugs, are about 10 times higher than would be expected if the drug had never been taken.
