Chemotherapy

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

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

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

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

Vesicles release neurotransmitter into synaptic cleft L. Binnington

Neurotransmitter binds to receptors & activates them L. Binnington

Enzymes are released to break down the neurotransmitter L. Binnington

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

Vesicles are replenished with new & reused neurotransmitter L. Binnington

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

Antipsychotic drugs These are also known as CONVENTIONAL ANTIPSYCHOTICS and 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

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

L. Binnington

L. Binnington

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

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

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

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

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

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

Antidepressant Drugs Depression is a mood disorder 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

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

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

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

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

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

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