Biological explanations - dopamine hypothesis Flashcards
What is the dopamine hypothesis?
Symptoms are caused by extreme levels of dopamine
What causes positive symptoms?
Hyperdopaminergia at D2 receptors in the subcortex
What is hyperdopaminergia?
High levels of dopamine
What causes negative symptoms?
Hypodopaminergia at D1 receptors in the prefrontal cortex
What is hypodopaminergia?
Low levels of dopamine
What is research evidence for the cause of positive symptoms?
Howes
What was Howes study?
A PET scan, who found much higher dopamine at D2 receptors in the subcortex, with a large effect size of 0.8
What is research evidence for the role of dopamine and negative symptoms?
Okubu
What was Okubu’s study?
A PET scan, and found lower dopamine at D1 receptors in prefrontal cortex
What is a strength of Howes’ study?
It is a meta-analysis so merges results from many studies
Why can you not conclude dopamine levels cause schizophrenia from scanning studies?
Scans are non-experimental, so its unclear is dopamine causes schizophrenia, schizophrenia effects dopamine levels or something else causes both
What do drug trials do?
All reduce dopamine at D2 receptors, and are quite effective for positive symptoms, and those that increase dopamine at DQ receptors in prefrontal cortex are quite effective for negative symptoms
What does evidence from drug trials show?
They they are effective for 2/3 of patients, not all
What is the result of drug trials?
If they work, it suggests that the causes are related to whatever the drug is doing
What are the issues with drug trials?
They are experimental and the indepedant variable is whether they are given the antipsychotic or placebo, but antipsychotics are only partially effective and could target the wrong neurotransmitter
