Chemotherapy

1. Chemotherapy

2. Assumption of the Biological Approach • The biological approach is interested in how behaviour is influenced by chemical imbalances in the brain • Chemotherapy tries to correct these imbalances

3. What are these key terms? Type your answer into the box. Neuron Synapse Neurotransmitter Antagonists L. Binnington

4. Did you get them right? Neuron = a nerve cell, which transmits signals through the nervous system. Uses electrical impulses and chemicals. Synapse = the gap between two neurons, chemicals pass across the gap to stimulate an electrical impulse in the next neuron Neurotransmitter = chemical substance which transmits messages across a synapse, by fitting into receptor sites and stimulating the next neuron Antagonists = drugs which reduce the activity of a particular neurotransmitter, usually by blocking the receptor sites

5. Watch the animation • On the next slide you will see an animation to recap how messages are transmitted across the synapse • I’m sure you already know this… let this jog your memory! L. Binnington

6. Vesicles release neurotransmitter into synaptic cleft L. Binnington

7. Neurotransmitter binds to receptors & activates them L. Binnington

8. Enzymes are released to break down the neurotransmitter L. Binnington

9. Excess neurotransmitter is taken up by the pre-synaptic neurone L. Binnington

10. Vesicles are replenished with new & reused neurotransmitter L. Binnington

11. Antipsychotic drugs • These are a form of major tranquilliser used to treat schizophrenia. • Before they were introduced in the 1950s schizophrenia was seen as an untreatable disorder and a diagnosis usually led to a stay in a mental institution. • These drugs were a major breakthrough, where other physiological therapies (including ECT and Insulin shocks) had failed. L. Binnington

12. Antipsychotic drugs • These are also known as CONVENTIONAL ANTIPSYCHOTICSand they reduce psychotic symptoms • They also produce neurological symptoms • An example is a drug called chlorpromazine • CONVENTIONAL ANTIPSYCHOTICS reduce the positive symptoms of schizophrenia, but don’t affect the negative L. Binnington

13. Antipsychotic drugs • As an excess of the neurotransmitter dopamine has been linked to the symptoms of schizophrenia, these drugs bind to dopamine receptors and block the build up of dopamine. The post-synaptic neuron is not stimulated and the symptoms are reduced. • It is thought that the parts of the brain linked too schizophrenia (through too much dopamine) are in the cerebral cortex and limbic systems L. Binnington

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16. Antipsychotic drugs • Antipsychotic drugs reduce symptoms such as hallucinations and delusions by sedating the parts of the brain responsible for their occurrence. • Another system linked to dopamine is responsible for motor functions • This system can degenerate, becoming the disorder known as Parkinson’s disease. • Symptoms include tremors, loss of balance, rigidity in muscles, and difficult breathing L. Binnington

17. Antipsychotic drugs • Unfortunately for schizophrenia sufferers, neuroleptics can produce Parkinson’s disease-like symptoms as a side effect • This is because the drugs interfere with the dopamine in these areas too • Some schizophrenics are reluctant to take these drugs as a result L. Binnington

18. Antipsychotic drugs • Although these Parkinson’s symptoms tend to be temporary, prolonged use of conventional anti-psychotics can lead to tardive dyskinesia • Look up this disorder – why is it linked to schizophrenia? L. Binnington

19. Antipsychotic drugs • Other side effects include… • Windgassen (1992) • 50% report sedation • 18% have poor concentration • 16% suffer a reduction in salivation • 16% get blurred vision L. Binnington

20. Antipsychotic drugs • However, there is a silver lining!! • Clozapine is a drug that has been recently introduced • It produces fewer side effects than other drugs • This has also improved both the positive and negative symptoms of schizophrenia • 30-50% improve whilst on the drug L. Binnington

21. Clozapine • However, 2% develop a potentially fatal blood disorder and so they need to be monitored • Clozapine is also more expensive than other drugs L. Binnington

22. Antidepressant Drugs • Depression is amooddisorder where the patient feels low (don’t worry – we go into more detail later in the course) • This low feeling is connected to a low level of the neurotransmitter serotonin in the synapse between nerve cells. L. Binnington

23. Antidepressant Drugs – How they Work • Reducing the rate of reabsorption • Blocking the enzyme that breaks down the neurotransmitter • Either action would increase the amount of neurotransmitter available to transmit impulses to neighbouring cells. L. Binnington

24. Antidepressant Drugs – How they Work • Selective Serotonin Reuptake Inhibitors • SSRIs - Eg PROZAC • These drugs stop Serotonin being reabsorbed back into nerve cells. • Because it is there longer it can pass on more impulses. L. Binnington

25. Antianxiety drugs • Anxiety and stress are commonly treated by Benzodiazepines (BZs) eg Valium. • They work on the Central Nervous System L. Binnington

26. Antianxiety Drugs – How BZs Work • Increase the activity of GABA (a neurotransmitter) which naturally reduces anxiety. • GABA locks on to receptor cells and opens up a channel allowing chloride ions into the neuron, making it harder to be stimulated and slowing down its activity. • The result is a feeling of relaxation L. Binnington

27. Antianxiety Drugs – How Beta-Blockers(BBs) Work • Reduce activity of adrenaline and noradrenaline (hormones) • Bind to receptors on target organs (eg heart) making them harder to stimulate and so reducing arousal – lower blood pressure and less anxiety • Used by snooker players and musicians L. Binnington

28. Effectiveness of Chemotherapy • Popular with patients – easy to use • Side-effects • Antipsychotics – tardive dyskinesia • Antidepressants – increased suicide risk • Effective in reducing symptoms – compared to placebos L. Binnington