1. Schizophrenia: drugs Synaptic transmission Mechanisms of drug action Drugs used with schizophrenia psychlotron.org.uk

2. Neurones Source: science photo library Neuronal cell bodies Synapses occur at the junctions Axons psychlotron.org.uk

3. Synapses Neurones transmit signals electrically along their axons The synapses (junctions between neurones) transmit signals chemically Most drugs act by interfering with events at the synapse psychlotron.org.uk

4. Synapse Vesicles filled with neurotransmitter Location of receptors (post- synaptic density) Synaptic cleft Source: neuroscience.wustl.edu psychlotron.org.uk

5. Vesicles release neurotransmitter into synaptic cleft psychlotron.org.uk

6. Neurotransmitter binds to receptors & activates them psychlotron.org.uk

7. Enzymes are released to break down the neurotransmitter psychlotron.org.uk

8. Excess neurotransmitter is taken up by the pre-synaptic neurone psychlotron.org.uk

9. Vesicles are replenished with new & reused neurotransmitter psychlotron.org.uk

10. Drug Therapies Increase synaptic activity by: Causing more neurotransmitter to be released Introducing a chemical that acts like the neurotransmitter Preventing breakdown of neurotransmitter Preventing reuptake of neurotransmitter psychlotron.org.uk

11. Drug therapies Decrease activity by: Increasing rate of neurotransmitter breakdown Blocking off receptors psychlotron.org.uk

12. Antipsychotic medication Neuroleptics (e.g. chlorpromazine) bind to DA receptors without activating them psychlotron.org.uk

15. Effectiveness Older (typical) drugs (e.g. chlorpromazine) Short term beneficial effect in 75% of patients (Davis et al, 1989) Long term beneficial effect in 55-60% (Davis et al, 1993) Most effective against positive symptoms High risk of side effects psychlotron.org.uk

16. Side effects Extrapyramidal side effects (EPS) Parkinson’s-type symptoms Postural & motor abnormalities Other side effects Sedation Weight gain Seizures psychlotron.org.uk

17. Effectiveness Newer (atypical) drugs (e.g. clozapine) As effective as typical drugs on positive symptoms; better for negative symptoms (Bilder et al, 2002) More effective with treatment-resistant patients (DeNayer et al, 2003) Less risk of EPS, but other side effects may occur (e.g. blood disorders) psychlotron.org.uk

18. Typical vs. atypical DA receptor tightly bound; slow release from receptor loosely bound; fast release from receptor Drug psychlotron.org.uk