Cause of schizophrenia - Neurotransmitters

Question 1

Functions of dopamine

Answer 1

Reward, motivation and addiction.
People repeat behaviours that lead to dopamine release.

Question 2

Functions of glutamate

Answer 2

Regulation of dopamine
Involved in learning and memory regulates development.

Question 3

Functions of GABA

Answer 3

Regulates the ability for chemical messages to be sent.
Calms firing nerves in the CNS
High levels improve focus, low levels cause anxiety.
Motor control and vision

Question 4

Functions of serotonin

Answer 4

Works in contrast with dopamine - provides pleasure.
Helps sleep cycle and digestive system
Affected by light exposure and exercise

Question 5

Main points of the dopamine hypothesis

Answer 5

• Dopamine in excess causes positive symptoms of Schizophrenia
• Studies using amphetamine have shown an increase in psychotic symptoms
• May be caused by excess dopamine and low levels of beta hydroxylase (enzyme that breaks down dopamine)
• Hypersensitive D2 receptors leading to more dopamine being absorbed.
• Thought that patients have abnormally high numbers of the D2 receptor, which results in more dopamine binding.

Question 6

Meso-limbic pathway

Answer 6

A brain circuit that depends on dopamine reward pathway. When a pleasure experience is experienced, the meso-limbic pathway is activated, causing dopamine release. Enjoyable activities, trigger increase and so positive symptoms.
High levels of dopamine leading to positive symptoms

Question 7

Meso- cortical pathway

Answer 7

A brain circuit that depends on dopamine. It is linked to reward-seeking and motivated behaviour and emotion, links to PFC. Lacks of normal organisation, cognitive deficits and motivation.
Low levels of dopamine leading to negative and cognitive symptoms

Question 8

Amphetamines

Answer 8

Give similar to those of excess dopamine.
Dopamine agonist, stimulating nerve cells containing dopamine causing the synapse to be flooded with NT.
Large doses of the drug can cause positive symptoms.
Amphetamines also create high alertness which is more symptoms of mania, so the explanation doesn’t fit exactly as you would think.
Angrist et al

Question 9

Parkinsons disease

Answer 9

Low levels of dopamine are found in people who suffer from this disease.
Grilly 2002 - those who were taking drugs to increase activity of dopamine were developing schizophrenic symptoms
Lindstroem et al 1999 - used PET scans to be able to trace a drug called L-DOPA which was taken up more quickly in the schizophrenic patients as they produce more dopamine than a control group.

Question 10

Glutamate on schizophrenia

Answer 10

• Important in learning memory, neural processing and brain development. It allows us to make some stimuli more important than others. Enables us to be selectively attentive- focusing on one thing and ignoring others.
• Low levels explain why schizophrenics have difficulty with sustained attention, cognitive control and working memory.
• Failure in cerebral cortex may lead to negative symptoms whereas glutamate failure in basal ganglia may lead to positive symptoms

Question 11

Serotonin on schizophrenia

Answer 11

• More recent (second generation) anti-psychotics that target serotonin as well as dopamine have been found to be more effective in treating schizophrenia.
• Suggests that serotonin plays a role in illness.

Question 12

GABA on schizophrenia

Answer 12

• People with schizophrenia have lower levels of GABA
• The lower the level, the more serious the symptoms