Schizophrenia: Biological Explanations

Question 1

What are the 2 biological explanations for schizophrenia?

Answer 1

genetic explanation
the dopamine hypothesis(neural correlates)

Question 2

Describe the genetic explanation for schizophrenia
-make 4 points

Answer 2

-schizophrenia is inherited through generations through the transmission of genes
-the inheritance pattern is complex and involves a number of affected genes
-100s of genes are thought to be involved(polygenic)
-candidate genes involved in schizophrenia include PCM1 and DRD3

Question 3

What does the candidate gene PCM1 do?

What is the DRD3 candidate gene?

Answer 3

it codes for a protein involved in cell division

a dopamine receptor gene

Question 4

Give a strength of the genetic explanation of schizophrenia

Answer 4

+supporting evidence from twin studies
Gottesman 1991- found concordance rates for schizophrenia were 17% for DZ twins and 48% for MZ twins

this evidence shows that genetics are involved in the cause of schizophrenia , enhancing the validity of the explanation

Question 5

State 3 issues with twin studies and explain how these are weaknesses of the genetic explanation for schizophrenia

Answer 5

1)concordance rates are never 100% , this suggests genetics aren’t the only cause of schizophrenia , other factors are also important , this challenges the explanation and suggests its incomplete

2)sample size , MZ twins are rare and only 1% of them would be expected to be schizophrenic , means we should be cautious when drawing conclusions

3)twins also share an environment , this makes it difficult to determine what is due to genetics and what isn’t

Question 6

Give another strength of the genetic explanation for schizophrenia

Answer 6

+supporting evidence from adoption studies
Tienari 1991-study involved 2 groups , G1 had 155 adopted children who’s biological mums were schizophrenic and G2 was a matched group of adopted children who had no family history of schizophrenia
Findings-10% in G1 developed SZ and in G2 only 1% did

this provides strong evidence that genetics are an important cause of schizophrenia , however it does suggest that the genetic explanation is incomplete

Question 7

What does the neural correlates explanation for schizophrenia state?

make 1 point

Answer 7

that measurements of brain structures and brain neurochemistry correlate with symptoms of schizophrenia

Question 8

What is dopamine , where is it found and what is it associated with?

Answer 8

dopamine is a neurotransmitter found in the limbic system , it is associated with attention and motivation

Question 9

Make 2 points about how dopamine activity is linked to schizophrenia according to the dopamine hypothesis

Answer 9

-has been linked to excess activity of dopamine in areas below the cortex(subcortical) of the brain
-has been linked to low activity of dopamine in the prefrontal cortex

Question 10

What is the name given to excess activity of dopamine in the brain

State the same for low activity

Answer 10

excess-hyperdopaminergia
low-hypodopaminergia

Question 11

State 3 mechanisms that could be the cause of hyperdopaminergia

Answer 11

-elevated presynaptic dopamine(more being synthesised and stored in vesicles)
-excess dopamine released into synapse
-increased density of receptors on postsynaptic neuron

Question 12

What may disturbances to dopamine neurons cause problems with(3)?

Answer 12

problems with perception attention and thought

(all symptoms of schizophrenia)

Question 13

Is dopamine imbalance inherited or influenced by environmental factors (eg drug use)

Answer 13

can be either

Question 14

Give a strength of the neural correlates explanation( the dopamine hypothesis)

Answer 14

+has led to the development of antipsychotic drugs
they block the activity of dopamine in the brain and have been effective at reducing positive symptoms of schizophrenia such as hallucinations

this suggests that dopamine over activity is involved in schizophrenia which enhances validity

Question 15

Give a however point for the neural correlates explanation
( a weakness)

Answer 15

-contradictory evidence
not all schizophrenia patients benefit from dopamine antagonist drugs
Clozapine-is a v effective treatment that binds to dopamine and serotonin receptors

this suggests that dopamine over activity isn’t the only cause of schizophrenia , suggests explanation is incomplete

Question 16

Give two general weaknesses of both explanations

Answer 16

-research evidence is correlational so its impossible to say that genetics or dopamine activity is the cause of schizophrenia

-other explanations , there are many environmental risk factors involved in schizophrenia including pregnancy complications , prenatal stress , psychoactive substance abuse and markers of social adversity

Question 17

What are examples of markers of social adversity?
give 3

Answer 17

unemployment , childhood abuse and migration

Question 18

Give a general strength of both explanations

Answer 18

+practical apps
knowledge of the biological reasons/factors involved in SZ has led to the development of treatments that effectively reduce symptoms such as anti-psychotic meds
this shows that research has been beneficial in the real world , enhancing external validity

Question 19

Issues and Debates-

Discuss the following issues and debates regarding the biological explanations of SZ (give a + and - for both)
Reductionism
Determinism

Answer 19

Reductionism-can be seen as oversimplifying a complex disorder therefore a more holistic view may be better

However… a reductionist explanation offers avenues for treatments such as drugs

Determinism-suggests SZ is due to a genetic predisposition we have no control over

However… if we know what can predispose people we can intervene earlier to prevent onset as we know who is at risk