Biological explanations Flashcards

1
Q

What are the 3 biological explanations for schizophrenia?

A
  • Genetics
  • Dopamine (Hyperdopaminergia/ Hypodopaminergia)
  • Neural correlates
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2
Q

What have researchers suggested in relation to genetics as an explanation of schizophrenia?

A
  • Some people may have a genetic disposition to schiz.
  • So the condition is at least partly inherited
  • disorder will run through families through faulty genes
  • No one gene is likely to be responsible for all cases but several genes are involved (polygenic)
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3
Q

What did Ripke et al 2014 report on how many genes & what genes were responsible?

What did Hong 2001 find in relation to Chinese patients with Schiz?

A
  • 108 genetic variants
  • variations of chromosome 8 & 11
  • C4 gene
  • variation of the TPH gene was more common with Chinese patients, which codes for serotonin production
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4
Q

What is the function of the C4 gene & how does it relate to the development of schiz?

A
  • Immune molecule outside of the CNS (Central Nervous System) that helps to contain infection
  • C4 gene is expressed by neurons & located at synapses
  • C4 mediates synapse pruning during development, something different from C4’s role in the immune system
  • excessive pruning could lead to symptoms of schiz.
  • This may explain why schiz. arises in adolescence & why schiz. patients have a thinner cerebral cortex with fewer synapses
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5
Q

What 4 instances did Gottesman & Shields 1991 find between schiz & genetics?

(Children of parents)
(MZ identical twins)
(First degree)
(Second degree)

A
  • Children of 2 schiz patients who share 100% genetic similarity: 46% chance of developing schiz
  • MZ twins (identical) who share 100% genetic similarity: 48% chance of developing schiz
  • First degree relatives (children) share 50% genetic similarity: 13% chance of developing schiz IF a parent was diagnosed
  • Second degree relatives (grandchildren) share 25% genetic similarity: 5% chance of developing schiz IF a grandparent was diagnosed
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6
Q

Why do adoption studies have an advantage over twin & family studies?

A
  • If adopted you can solely look at genetics rather than schiz family members in their direct environment
  • adopted child is isolated from their schiz family
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7
Q

Adoption study by Tienari 2000?
(164 Finnish kids)

A
  • Used 164 adopted kids in Finland who’s biological mothers were schiz.
  • Kids were matched with kids who’s mothers did not have schiz
  • results: 11/164 (schiz mother) kids had been diagnosed with schiz v.s. 4/164 kids (control group helping to validate data)
  • Shows schiz has a genetic component as adopted children do not share environmental influences with their biological mothers
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8
Q

AO3 genetic explanation of schiz
Jospeh 2004?

A
  • Genetic similarity increases development of schiz
  • Before 2001 pooled data showed 40% concordance rate with MZ twins (100% similarity)
  • also showed &% concordance rate for DZ twins (50% share)
  • Higher concordance for MZ shows genes have an influence on the development of schiz
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9
Q

AO3 genetic explanation of schiz
Psychological explanation instead?

(can use eval for all biological explanations of schiz)

A
  • Psychological explanation is more influential
  • Claims poor family relationships & maladaptive behaviour affects a growing child’s perception of reality & how they interact with their environment
  • If these problems persist into adulthood, schiz may develop
  • Shows biological explanation may not be the sole reason for schiz development
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10
Q

AO3 genetic explanation
Biological is reductionist?
(maybe that’s a good thing?)

A
  • reductionist
  • Highlights genetics & neurological imbalances in the brain
  • this is viewed as the main catalyst of the disorder
  • However the reductionism can be useful in developing treatments for sz
  • anti-psychotic drugs work by reducing the effects of dopamine & so reduce symptoms of disorder
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11
Q

AO3 genetic explanation
Issues with cause & effect?
(environment/genes)

A
  • Genetics results in issues with cause & effect
  • Despite mothers sharing 50% genetic similarity with a parent that may be a sufferer/other first degree relatives
  • family members tend to share an environment as well as genes
  • Environmental factors can disrupt associated cause & effect through genetics
  • behaviour can be adopted through the environment, imitating schiz symptoms or contribute towards the development of schiz
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12
Q

Outline the dopamine hypothesis?

A
  • Aka Hyperdopaminergia (Hyper - high)
  • Biochemical explanations argue schiz is caused by elevated levels of dopamine (DA)
  • High DA activity in key synaptic sites e.g. mesolimbic pathway & limbic system
  • Excess of DA causes a ‘system overload’ due to increases in impulses, triggering positive symptoms of schiz e.g. Hallucinations
  • Pre synaptic neurons can be a factor by releasing too much DA
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13
Q

Outline 2 observations that support the dopamine hypothesis of schiz?

A
  1. Antipsychotics: relieve some symptoms by blocking DA
    - These have been shown to be effective in up to 85% of patients (antagonistic)
  2. Post-Mortem studies have shown a higher concentration of DA in schiz patients
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14
Q

Outline the revised dopamine hypothesis?

A
  • Modified due to inconsistencies in research
  • Davis (1991) pointed out in PFC (Pre-Frontal Cortex) there are no D2 receptors instead there is a deficiency of DA
  • Davis suggested low levels DA are responsible for negative symptoms (avolition) this is called Hypodopaminergia (Hypo - low)
  • PFC responsible for executive functions (rational thoughts, decision making e.g. things associated with negative symptoms)
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15
Q

AO3 Dopamine research support
Randrup & Munkvad (1966)?

A

P - Randrup & Munkvad created schiz behaviour in a rat sample by giving them dopamine agonists (amphetamines)
E - The rats dopamine levels were raised 3 times a day for 6 days
- Rats then displayed prolonged abnormalities including inability to filter out external sounds
- This was reversed using anti-psychotic drugs
L - supports dopamine hypothesis towards development of schiz

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16
Q

AO3 Dopamine Alternative explanation of cognitive explanation?

A

P - There are alternative explanations towards development of schiz
E - Cognitive psych explanation argues many schiz sufferers have faulty information processing & dysfunctional thought processes
E - A malfunction within the central monitoring system (CMS) could explain positive symptoms
L - Shows dopamine explanation may not be the primary cause for schiz

17
Q

AO3 Dopamine
Practical application?

A

P - Real world application is that drug treatment can be introduced can be introduced to aid sufferers of schiz by reducing DA levels
E - Antipsychotic drugs block activity of DA working as an antagonist against DA NT’s
E - Medication been effective in up to 85% of pt’s
L - Therefore dopamine explanation has helped to create medication aiding sufferers with their symptoms

18
Q

AO3 Dopamine
Strength in contributing to Diathesis-Stress model?

A

P - Strength of high dopamine explanation of schiz is that it contributes to diathesis-stress model
E - Dopamine would be the diathesis (biological element) & this would interact with environmental factors e.g. urban living (stressors)
E - Could potentially result in the development of schiz through interactionism between biological & environmental facotrs
L - Dopamine hypothesis of schizophrenia is a vital element in wholly explaining the causes of schiz

19
Q

Outline further Neural correlates of schiz?

A
  • Schizophrenia is a result of further abnormalities in the brain & biochemistry
  • Abnormalities can be genetically inherited or through experience
20
Q

Outline Enlarged Ventricles as a neural correlate?

A
  • Neuroimaging techniques suggest anatomical differences between brains of schiz & those non-schiz people
  • Schiz - enlarged ventricles found in brain fluid-filled cavities
  • Only 15% difference found in unmedicated patients, so drugs not relevant
  • Enlargements appear in onset of schiz
21
Q

Outline Hypofrontality as a neural correlate?

A
  • Hypofrontality correlates with reduced blood flow in PFC (Pre Frontal Cortex)
  • This is seen with negative symptoms of schiz patients (emotional & cognitive kind) e.g. avoltion (social withdrawal) & speech poverty (alogia)
22
Q

Outline Hippocampus - amygdala region as a neural correlate?

A
  • Hippocampus - Amygdala is reduced in size
  • Exacerbates positive symptoms (Hallucinations/Illusions of Grandeur)
  • Amygdala (emotion)
  • Hippocampus (memory)
23
Q

AO3 Neural correlates research against
McEwen (2007)?

A

P - Research against from McEwen (2007)
E - Argues that nurturing influences could cause structural changes in the brain, making explanation incomplete
E - Children & Adolescent brains more sensitive to chronic stressors (physical abuse) which shapes the structure of cortical regions
L - Therefore environmental factors can cause schiz maybe more so than biological/supports diathesis-stress model

24
Q

AO3 Neural correlates
Alternative explanation due to cause & effect?

A

P - Other explanations may prove to be more substantial as NC has issues with cause & effect
E - Just because there’s a correlation between brain areas & symptoms does not mean the neural mechanism has caused the symptoms
E - Maybe the difference in activity levels could be a consequence of schiz and the changes in brain areas is due to the schizophrenia
L - So it is ambiguous as to what is causing the symptoms

25
Q

AO3 Neural correlates
Research support Suddeth (1990)?

A

P - Research support from Suddeth (1990) suggests there are neural correlates that cause schiz
E - Suddeth conducted study on MZ twins we can assume neuro-physical differences cause schiz
E - It is therefore unlikely for schiz to be due to external factors as twins are genetically identical & grow up in a similar environment
L - This strengthens the neural explanation for the development of schiz

26
Q

AO3 Neural correlates
Cross illness issues for enlarged ventricles?

A

P - Issue with Neural correlates as an explanation for schiz is enlarged ventricles, not exclusive to schiz
E - They may occur in brains of Parkinson’s disease sufferers & other disorders
E - Only some patients have enlarged ventricles, not all
- ‘Normal’ individuals also have enlarged ventricles & are schiz
L - Implies we cannot use enlarged ventricles as a biological explanation for NC’s with credibility