Carlsson et al (2000)

Question 1

Aim

Answer 1

Review studies in relationship between neurotransmitter levels on symptoms of schizophrenia (focusing on hyperdopaminergia and hypoglutamatergia)
Look at impact side effects of antipsychotics
Produce drugs that reduce relapse levels and negative side effects

Question 2

Literature Review

Answer 2

32 studies investigating role of neurotransmitters in development of schizophreia symptoms
Research from 1978-1999
Evidence from studies on recreational drugs that induce psychosis
Link to amphetamines (increase dopamine) with schizophrenia

Question 3

Type of study they used

Answer 3

Brain scans
Measure neurotransmitters
Recreational drugs
Effectiveness of drugs

Question 4

Results with PCP

Answer 4

Phencyclidne (PCP) antagonist of NMDA (glutamate) receptors
Drug inhibits glutamate, reducing action in areas of the brain
PCP more likely to result in psychosis than amphetamine

Question 5

Results with relation between glutamate and symptoms

Answer 5

Low glutamate = psychotic symptoms
Low glutamate = high dopamine

Question 6

What does glutamate failure result in

Answer 6

Glutamate failure in cerebral cortex = negative symptoms
glutamate failure in basal ganglia = positive symptoms

Question 7

Results with drug clozapine

Answer 7

Highly effective
Fewer negative side effects
Both antidopaminergic and antiserotonergic functions = low dopamine and serotonin
Reduces positive and negative symptoms
Highly effective in patients not previously responsive to treatment

Question 8

What patients are difficult to treat

Answer 8

Patients with hypoglutamatergia
Most drugs only change serotonin and dopamine levels

Question 9

Conclusion (what needs to change about treatment of schizophrenia)

Answer 9

Need to consider other neurotransmitters (like glutamate), don’t just focus on dopamine
Blocking dopamine gives bad side effects so better to look at other neurotransmitters that don’t cause side effects
Many types of schizophrenia caused by abnormal levels of DIFFERENT neurotransmitters to dopamine

Question 10

Strength Study

Answer 10

Carlsson and Carlsson (1989)

Question 11

What did Carlsson and Carlsson (1989) find

Answer 11

Gave mice drug to reduce motor activity followed by MK-801 (reduce glutamate and increase serotonin and dopamine)
MK-801 restarted motor activity but continued use resulted in highly abnormal psychotic-like behaviour
Schizophrenia may be caused by glutamate irregularity and glutamate antagonists may be effective treatements

Question 12

Weakness study

Answer 12

Luhrmann (2015)

Question 13

What did Luhrmann (2015) find

Answer 13

Luhrmann (2015)
US participants more likely to hear violent voices whereas Ghanian and Indian people heard positive experiences
Ignored cultural factors as conclusions are based on animal models
Animals models fail to capture holistic lives experience of schizophrenia including side effects and symptoms

Question 14

CA of strength

Answer 14

Since study two neurotransmitters (anadamide and nitric oxide) have been identified as important in psychosis
Leading to new tratments
Also suggested neurotransmitter imbalances may arise from autoimmune problems

Question 15

Another weakness

Answer 15

Some evidence for dopamine hypothesis based on people with schizophrenia during acute episodes
People with chronic schizophrenia may respond differently with their episodes
Research should consider all phases of disorder to make better conclusions

Question 16

Another strength (benefits)

Answer 16

Beneficial for patients whom current antipsychotic medications are ineffective
Large % don’t respond quickly or at all
New drug compounds may provide answer to problem

Question 17

Strength of methods used

Answer 17

Most used PET scans
Reliable method
Objective methodology