Schizophrenia - Biological explanations

Question 1

1 What is L-dopa?

Answer 1

Drug used to increase the amount of dopamine in parkinsons patients - developed paranoid delusions and had a detached emotional response

Question 2

1 What are the pathways in the limbic system?

Answer 2

Mesolimbic - carries signals from the VTA to nucelus accumbens - too much dopamine causes overstimunlation and positive symptoms
Mesocortical - carries signls from VTA to frontal labe - dopamine abnormalities are linked with negative symptoms

Question 3

1 What did Davis et al note?

Answer 3

Low levels of dopamine in D1 receptors of frontal lobe in many individuals with negative symptoms

Question 4

1 Supporting research (family members) for dopamine hypothesis?

Answer 4

Gottesman - as genetic similarity increased, so did the probability of both individuals developing schizophrenia

Question 5

1 Limitations of Gottesman’s study?

Answer 5

Not what the hypothesis suggests so is only useful as a partial explanation

Question 6

1 Alternative explanation (genetics) for dopamine hypothesis?

Answer 6

There were 108 loci association with schizophrenia

Question 7

1 Limitations of alternative explanation?

Answer 7

Schizophrenia is a very complex matter and is more than just a few abnormal dopamine genes

Question 8

1 Methodological issues for dopamine hypothesis?

Answer 8

Difficult to measure neurotransmitter levels - needs a lumbar puncture to obtain cerebrospinal fluid - can be uncomfortable
Diet and drug use can influence metabolite levels so caution needs to be taken when drawing conclusions

Question 9

1 Why is the dopamine hypothesis a partial explanation?

Answer 9

Role of serotonin cannot be ignored - not only dopamine is involved
Typical antipsychotics - block D2 receptors but not all schizophrenics benefit
Atypical antipsychotics - bloth dopamine and serotonin receptor sites - more effective

Question 10

2 What are ventricles?

Answer 10

Cavities filled with cerebrospinal fluid
Larger in those with schizophrenia

Question 11

2 What did Weinberger et al found?

Answer 11

Ventricular size was greater in people with chronic schizophrenia than in people in control group
40% - outside range of control group - substantially different

Question 12

2 What did Andreason find?

Answer 12

Schizophrenica had ventricles 20-50% larger than controls

Question 13

2 What is cortical atrophy?

Answer 13

Loss of neurons in cerebral cortex - can occur all over the brain or focussed in limited areas

Question 14

2 What does cortical atrophy result in?

Answer 14

Wideniing of grooves (sulci) covering the cerebral cortex
Characterises 20-35% of schizophrenics

Question 15

2 What did Vita et al find?

Answer 15

33% of shcizophrenics showed moderate to severe atrophy - not related to individual differnces like age but related to sex specifically male

Question 16

2 What is reversed cerebral asymmetry?

Answer 16

usually temporal, parietal and occipital lobes are larger on the left and the frontal lobe is smaller on the right - opposite for schizophrenics

Question 17

2 What can asymmetry explain?

Answer 17

Alogia - language function is located on the left hemisphere as it is smaller in those with schizophrenia

Question 18

2 What did Luchins et al find?

Answer 18

Increased frequency of ‘reversals’ in both frontal and occipital lobes in schizophrenics

Question 19

2 Methodological issues (evidence) of structural abnormalities?

Answer 19

Use of brain scans - allow us to see the living brain in action so more precise about abnoralities - highly reliable
Risk of psychological harm - can cause distress to those without schizophrenia - may experience delusions and fear brain scanning more than usual

Question 20

2 Supporting research (ventricles) for structural abnormalities?

Answer 20

McCarley - presence of enlarged ventricles in people with schizophrenia is the most reliable finding in research using brain scans

Question 21

2 Limitations of abnormalities?

Answer 21

Abnormalities arent always found in schizophrenics - Age and gender can affect pattern of abnormalities
Abnormalities are also present in other illnesses (bipolar)

Question 22

2 Methodological issues (antipsychotics) for structural abnormalities?
Lyon et al?

Answer 22

Any abnormalities may be a result of medication and not the illness.
Lyon - as doses increased, density of brain tissue decreased