Chemotherapy. Assumption of the Biological Approach The biological approach is interested in how behaviour is influenced by chemical imbalances in the.

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

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What are these key terms? Type your answer into the box.

Neuron

Synapse

Neurotransmitter

Antagonists

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

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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!

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Vesicles release neurotransmitter into synaptic cleft

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Neurotransmitter binds to receptors & activates them

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Enzymes are released to break down the neurotransmitter

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Excess neurotransmitter is taken up by the pre-synaptic neurone

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Vesicles are replenished with new & reused neurotransmitter

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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.

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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

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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

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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

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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

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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?

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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

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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

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Clozapine

• However, 2% develop a potentially fatal blood disorder and so they need to be monitored

• Clozapine is also more expensive than other drugs

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.

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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.

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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.

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Antianxiety drugs

• Anxiety and stress are commonly treated by Benzodiazepines (BZs) eg Valium.

• They work on the Central Nervous System

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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 relaxationL. 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

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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

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