Biologial Explination for Sz Flashcards
What is the dopamine hypothesis
It claims that too much dopamine in certain regions of the brain cause postive Sz symptoms. Those with Sz are thought to have abnormally high D2 receptors on recieving neurons, resulting in more dopamine builing and neurons firing
How do amphetamines support dopamine hypothesis
Amphetamine is a dopamine agonist, which means it causes synapses to be flooded with dopamine. ‘Normal’ Individual exposed to large doses of amphetamines develop characteristic symptoms of Sz
How do dopamine antagonists support the dopamine hypothesis
Dopamine antagonists reduce activity of the neural pathways of the brain which use dopamine as a neurotransmitter, and these are the main element of antipsychotic drugs. They reduce positive symptoms like Hallucination
What is the revised dopamine hypothesis
Developed by Davis and Kahn, they suggested that postivie symptoms were caused by too much dopamine in subcortical areas of the brain, particularly the mesolimbic pathway. The negative symptoms are thought to be the result of a defecit of dopamine in the prefrontal area of the brain, specifically the mesocortical pathway
How is the prefrontal cortex involved in Sz
It has been hypothesised that the cognitive symptoms of Sz result from defecits within the PFC and it’s connections to other areas, particularly the hippocampus. Research has also shown that functions associated with the PFC (Reasoning and Judgment) are impaired in those with Sz
How is the hippocampus involved in Sz
Defecits in the nerve connections between the hippocampus and prefrontal cortex have been found to correlate with the degree of working memory impairments in Sz
How is grey matter involved in Sz
People with Sz have been found to have reduced volume of grey matter in their brain, particularly the temporal and frontal lobes. Many people with Sz, particularly those with negative symptoms, have been found to have enlarged ventricles, thought to be a consequence of nearby parts of the brain not developing properly
How is white matter involved in Sz
Research has found decreased mylenation (like nerve cell) in white matter pathways of sz patients compared to healthy controls, particularly between the PFC and Hippocampus
How have family studies supported a genetic basis for Sz
Gottesman found children with two Sz parents had a concordance rate of 46%, and one Sz parent had a concordance rate of 13%
How have twin studies supported a genetic basis for Sz
Joseph calculated that the pooled data for all Sz twin studies carried out prior to 2001 showed a concordance rate of MZ 40% and DZ 7.4%
How have adoption studies supported a genetic basis for Sz
Tienari et al studied 164 adoptees who’s mother had Sz, and 11 recieved a diagnosis of Sz compared to 4 of the 197 control adoptees.
What is an assumpton for twin studies into Sz (eval)
There is a crucial assumption in twin studies that the environments for MZ and DZ twins are equivalent, but Joseph pointed out that MZ twins are treated more similarly, encounter more similar environments and experience more ‘identity confusion’ than DZ twins. This suggests that the differences in concordance rate could be environmental
What is an issue with adoption studies for Sz (eval)
The idea that adoptees are not ‘selectively placed’, the idea that those who adopt those with a possible Sz background are no different from those who adopt children who’s background is normal. Due to the widespread beliefs about those with mental disorders, it is unlikely that those who are born to women with Sz are placed in same type of adoptive families as those with no such background
What is criticism of the dopamine hypothesis (eval)
Noll argued that antipsychotic drugs do not alleviate hallucinations and delusions in about 1/3 of those expereincing these symptoms, and that in some patient these symptoms are present despite dopamine levels being normal
What is supportive evidenc of drug treatment for Sz (eval)
Leucht carried out a meta-analysis of 212 studies and concluded that antipsychotic drugs tested in these studies were significantly better than a placebo in the treatment of postive and negative symptoms, through the effects of dopamine reduction
Who suggested the revised dopamine hypothesis
Davis and Kahn
Who did family studies into Sz
Gottesman
Who did twin studies into Sz
Joseph
Who did adoption studies into Sz
Tienari
Who provided evidence against the dopamine hypothesis
Noll
Who carried out a meta analysis of drug treatments
Leucht
