anti-psychotics

Question 1

what pathways are important in schizophrenia

Answer 1

Mesolimbic pathway (reward pathway)-ie ventral tegmental area (VTA), —> Nucleus Accumbens (NAcc)

Mesocortical pathway: VTA—>cerebrum (various areas of the cortex).Activation associated with positive schizophrenia symptoms, Inhibition associated with negative schizophrenia symptoms.

These are both DOPAMINERGIC pathways

Question 2

what are the “positive” symptoms of schizophrenia

Answer 2

Increased mesolimbic dopaminergic activity:
• Hallucinations: auditory & visual
• Delusions: Paranoia
• Thought disorder: Denial about oneself

Ie addition from the normal behaviour

Question 3

what are the “negative” symptoms of schizophrenia

Answer 3

Decreased mesocortical dopaminergic activity
• Affective flattening: lack of emotion
• Alogia: lack of speech
• Avolition/apathy: loss of motivation

ie loss of normal behaviour

Question 4

what drugs can be used in schizophrenia

Answer 4

Chlorpromazine-Primary mechanism of action – possibly D2 receptor antagonism – it inhibits dopamine D2 receptors
Side effects:
o High incidence: anti-cholinergic effects, especially sedation
o Low incidence: extrapyramidal side-effects (EPS)

Haloperidol: Very potent D2 antagonist (~ 50x more potent than chlorpromazine)
Therapeutic effects develop over 6-8 weeks
• Little impact on negative symptoms – maybe even worsening (alleviate the positive symptoms)
• Dopamine antagonism is good in the mesolimbic pathway, but NOT in the mesocortical pathway
• Side effects: High incidence – EPS (extra-pyramidal side effects)