1. Schizophrenia: brain chemicals
How might neurotransmitters be implicated in mental illness?

2. Today’s session You will learn about Context Commenting on evidence
Synaptic transmission
Drug treatments for psychological disorders
Schizophrenia
The dopamine hypothesis of schizophrenia

3. Synapses occur at the junctions
Neurones
Neuronal cell bodies
Axons
Source: science photo library
Synapses occur at the junctions

4. Synapses Neurones transmit signals electrically along their axons
The synapses (junctions between neurones) transmit signals chemically

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

6. Vesicles release neurotransmitter into synaptic cleft

7. Neurotransmitter binds to receptors & activates them

8. Enzymes are released to break down the neurotransmitter

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

10. Vesicles are replenished with new & reused neurotransmitter

11. The dopamine hypothesis
Schizophrenia is caused by excessive activity at synapses that use dopamine as their primary neurotransmitter
This causes abnormal functioning of DA-dependent brain systems, resulting in schizophrenic symptoms

12. Biology and Schizophrenia
Consistent evidence for abnormal brain functioning in S patients but no single factor identified.
Two syndromes?
Cause & effect issues everywhere
Confounding effects of drug treatment

13. What could be done to make dopamine synapses less active?

14. Antipsychotic medication
Neuroleptics (e.g. chlorpromazine) bind to DA receptors without activating them

17. 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

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

19. What implications arise from the side effects of antipsychotic drugs?

20. 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)

21. Typical vs. atypical DA receptor Drug
tightly bound; slow release from receptor
loosely bound; fast release from receptor
DA receptor
Drug