neurotransmitter explanation of schizophrenia

Question 1

what is the original dopamine hypothesis?

Answer 1

• hyperactivity of dopamine transmission
• hypersensitivity of D2 receptors in the brain so a larger effect is caused by dopamine
• causes positive symptoms such as hallucinations

Question 2

what can sensitivity to dopamine arise from and how can this be seen?

Answer 2

• genetic inheritance to brain lesioning and therefore biochemical abnormalities should be detectable
• postmortem examinations have shown the brains of people with Sz have higher density of dopamine receptors

Question 3

what is the revised dopamine hypothesis?

Answer 3

• positive symptoms caused by excess dopamine in subcortical areas
• negative and cognitive symptoms caused by deficits of dopamine in the PFC

Question 4

describe the mesocortical pathway

Answer 4

• VTA to the PFC
• involved with motivation and executive functioning
• deficits lead to negative and cognitive symptoms e.g. flattened mood

Question 5

describe the mesolimbic pathway

Answer 5

• VTA to basal ganglia
• involved with goal orientation, reward and attention
• excess dopamine in these areas leads to positive symptoms such as hallucinations and delusions

Question 6

what is the role that serotonin plays and how does clozapine effect serotonin?

Answer 6

• plays a role in mood and the sleep wake cycle
• in areas with low serotonin there was high dopamine linking to positive symptoms
• clozapine = affects the D1 and D4 receptors

Question 7

what is the role of glutamate?

Answer 7

• regulatory effect on dopamine
• low levels in cerebral cortex leads to negative symptoms
• glutamate failure in basal ganglia leads to positive symptoms

Question 8

what is a strength regarding antipsychotic drugs?

Answer 8

• block the activity of dopamine by reducing the stimulation of the dopamine system
• helps reduce symptoms of hallucinations and delusions
• strengthens the case of dopamine being a contributing factor

Question 9

strength regarding the explanation of negative symptoms?

Answer 9

• successfully explains the negative symptoms (reduction in activity at mesocortical pathways) which other explanations struggle to account for

Question 10

strength regarding post mortem studies and PET scans aswell as a study that shows this?

Answer 10

• have shown that dopamine receptors are greater in number or are hypersensitive
• Falkai et al = studied autopsies and found that people with Sz have larger number of receptors

Question 11

what does Grilly (2002) show about the explanation relating to parkinsons patients?

Answer 11

• parkinsons patients have low levels of dopamine
• Grilly = found that those who were taking drugs to increase activity were developing Sz symptoms

Question 12

what is a weakness regarding reductionism?

Answer 12

• attempts to explain a complex disorder using the smallest unit of explanation and fails to consider any social factors
• things are usually interactionist e.g. may be genetic predisposition that is triggered by social factors

Question 13

what is a weakness relating to drugs such as clozapine?

Answer 13

• newer antipsychotic drugs such as clozapine have been found to actually increase dopamine levels
• contradicts the dopamine hypothesis

Question 14

what did the study of Albert and Freidhoff find?

Answer 14

• some patients showed no improvement whatsoever after taking dopamine antagonists
• atypical neuropletics dont necessarily work by blocking only dopamine receptors