Neuronal explanation for Sz: Flashcards
What does the original dopamine hypothesis suggest?
Hyperdopaminergia
Claims excess of neurotransmitter dopamine in subcortical areas of the brain = positive symptoms of Sz.
Abnormally high numbers of D receptors = more dopamine binding = firing.
How was the dopamine link discovered?
Chlorpromazine = antihistamine
Given to Sz patients = reduction in symptoms
Used in Parkinson’s patients.
What does dopamine do?
Pleasure seeking neurotransmitter:
Blood flow, digestion, pancreatic function.
Contributes to feelings of:
~Alertness
~Focus
~Motivation
~Happiness
Give an example of a drug that increases dopaminergic activity:
Amphetamines = dopamine agonist
Stimulates nerve cells endings
.: Synapse flooded with neurotransmitter
Lead to characteristics of psychotic episode.
Give an example of a drug that decreases dopaminergic activity?
Block activity of dopamine in brain.
Eliminating hallucinations +delusions.
Dopamine antagonists.
What does the updated dopamine hypothesis suggest about Sz?
Sz result of low levels of dopamine in (prefrontal cortex) cortical regions of the brain.
Linked to cognitive functioning –> negative symptoms.
Davis + Kahn (1991):
+ve = excess dopamine in mesolimbic pathways.
-ve = deficit of dopamine in mesocortical pathways.
Additional AO1 points
Go back after exam and add these points in
Evaluation of neural correlates:
Evidence of effectiveness:
Leucht et al (2013):
Meta analysis of 212 studies.
Concluded all antipsychotic drugs tested in studies more effective than placebo in treatment of -ve and +ve symptoms.
Links to OG hypothesis model.
Increases validity
Evaluation of neural correlates:
COUNTERPOINT:
Noll (2009):
Argues antipsychotic drugs do not alleviate hallucinations
+ delusions in 1/3 of sufferers
Some people= hallucination still present despite normal dopamine levels.
Partial explanation.
Not same for every Sz patient.
Evaluation of neural correlates:
Role of Glutamate:
Central role of glutamate.
McCutcheon et al 2020:
Post-mortem/ live scanning = raised levels of glutamate in several brain regions of Sz ppl.
Several candidate genes = involved in glutamate production/processing
Other neurotransmitter involved
Partial explanation.
Evaluation of neural correlates
Early intervention:
Early intervention = prevent development of later stages of disorder.
Concept as ‘treatment as prevention’
North American Prodrome Longitudinal study (Addington et al 2015):
Used number of different assessments (neuroimaging)–> predict who will develop psychoses such as Sz.
Implications for economy: less money on treatments provided by GOV.
