Sc - Biological explanations for schizophrenia

Question 1

Biological explanations

Answer 1

Emphasise the role of inherited factors and dysfunction of brain activity in the development of a behaviour or mental disorder.

Question 2

Dopamine hypothesis

Answer 2

Claims that an excess of the NT dopamine in certain regions of the brain is associated with the positive symptoms of SZ.

Question 3

Genetics

Answer 3

Inherited factors make certain individuals more likely to develop a behaviour or mental disorder.

Question 4

Neural correlates

Answer 4

Changes in neuronal events and mechanisms that result in the characteristic symptoms of a behaviour or mental disorder.

Question 5

What are the 2 biological explanations for SZ?

Answer 5

Genetic factors

Neural correlates

Question 6

What genetic factors can we talk about for SZ?

Answer 6

Family studies
Twin studies
Adoption studies

Question 7

Explain family studies as a biological explanation for SZ

Answer 7

SZ is more common among biological relatives of a person with SZ, and that the closer the degree of genetic relatedness, the greater the risk.

Gottesman’s study - children with 2 schizophrenic parents had a concordance rate of 46%, children with one SZ parent had a rate of 13%, and siblings of a SZ person had a rate of 9%.

Question 8

What were the results of Gottesman’s family studies?

Answer 8

Gottesman’s study - children with 2 schizophrenic parents had a concordance rate of 46%, children with one SZ parent had a rate of 13%, and siblings of a SZ person had a rate of 9%.

Question 9

Explain twin studies as a biological explanation for SZ

Answer 9

If MZ (genetically identical) twins are more similar than DZ twins (only share 50% of genes), then this suggests that the greater similarity is due to genetic factors.

Joseph (2004) calculated that the pooled data for all SZ twin studies carried out prior to 2001 showed a concordance rate for MZ twins of 40.4% and 7.4% for DZ twins.

Question 10

What were the results of Joseph’s twin studies?

Answer 10

Joseph (2004) calculated that the pooled data for all SZ twin studies carried out prior to 2001 showed a concordance rate for MZ twins of 40.4% and 7.4% for DZ twins.

Question 11

Who did family studies?

Answer 11

Gottesman

Question 12

Who did twin studies?

Answer 12

Joseph (2004)

Question 13

Explain adoption studies as a biological explanation for SZ

Answer 13

Difficult to disentangle genetic and environmental influences for individuals who share genes and environment so studies of genetically related individuals who have been reared apart have been used.

Tienari et al. (2000) in Finland - of the 164 adoptees who biological mothers had SZ, 11 (6.7%) also received a diagnosis of SZ, compared to just 4 (2%) of the 197 control adoptees (non-SZ mothers).

Findings showed the genetic liability to SZ had been ‘decisively confirmed’.

Question 14

Who did adoption studies?

Answer 14

Tienari et al. (2000) in Finland

Question 15

What were the results of the Tienari et al. adoption studies?

Answer 15

Tienari et al. (2000) in Finland - of the 164 adoptees who biological mothers had SZ, 11 (6.7%) also received a diagnosis of SZ, compared to just 4 (2%) of the 197 control adoptees (non-SZ mothers).

Findings showed the genetic liability to SZ had been ‘decisively confirmed’.

Question 16

What neural correlates can we talk about for SZ?

Answer 16

Dopamine hypothesis

Specific brain areas

Question 17

Link between D2 receptors and SZ

Answer 17

Schizophrenics thought to have abnormally high numbers of D2 receptors on receiving neurons.

Question 18

What does schizophrenics having abnormally high numbers of D2 receptors on receiving neurons result in?

Answer 18

More dopamine binding and therefore more neurons firing.

Question 19

What evidence showed the key role played by dopamine?

Answer 19

Drugs that increase dopaminergic activity and drugs that decrease dopaminergic activity.

Question 20

What does amphetamine cause?

Answer 20

Dopamine agonist - stimulates nerve cells containing dopamine, causing the synapse to be flooded with the NT.

Question 21

What is a drug that increases dopaminergic activity?

Answer 21

Amphetamine.

Question 22

What does excess dopamine/amphetamine do to ‘normal’ individuals?

Answer 22

‘Normal’ individuals exposed to large doses of dopamine releasing drugs such as amphetamines can develop the characteristic symptoms of a schizophrenic episode, which generally disappear with abstinence from the drug.

Question 23

What drugs decreases dopaminergic activity?

Answer 23

Antipsychotics.

Question 24

What do antipsychotics do to dopamine?

Answer 24

Dopamine antagonists - block the activity of dopamine in the brain.

Question 25

How do antipsychotics decrease dopaminergic activity?

Answer 25

By reducing activity in the neural pathways of the brain that use dopamine as the NT.

Question 26

What do antipsychotics do to symptoms?

Answer 26

Eliminate symptoms such as hallucinations and delusions.

Question 27

Why are antipsychotics evidence for the hypothesis?

Answer 27

The fact that these drugs (dopamine antagonists) alleviated many of the symptoms of SZ strengthened the case for the important role of dopamine in this disorder.

Question 28

What did Davis and kahn (1991) propose about positive symptoms of SZ?

Answer 28

They are caused by an excess of dopamine in subcortical areas of the brain, particularly in the mesolimbic pathway.

Question 29

Who proposed that positive symptoms of SZ are caused by an excess of dopamine in subcortical areas of the brain, particularly in the mesolimbic pathway?

Answer 29

Davis and kahn (1991)

Question 30

From what are the negative symptoms of SZ thought to arise?

Answer 30

From a deficit of dopamine in areas of the prefrontal cortex (the mesocortical pathway).

Question 31

Who carried out a study on dopamine levels in people with SZ compared to those without?

Answer 31

Patel et al. (2010)

Question 32

How did Patel et al. (2010) compare dopamine levels in people with SZ to people without SZ?

Answer 32

Using PET scans.

Question 33

What did Patel et al. (2010) find about dopamine levels in people with SZ compared to those without?

Answer 33

Found lower levels of dopamine in the dorsolateral prefrontal cortex (DLPFC) of schizophrenic patients compared to their normal controls.

Question 34

What brain areas are known to be involved in SZ?

Answer 34

PFC
Hippocampus
Grey matter
White matter

Question 35

What is the PFC involved in?

Answer 35

Main are for executive control (i.e. planning, reasoning, and judgement).

Question 36

What research is there for a difference in the PFC of people with SZ?

Answer 36

Weinberger and Gallhofer (1997).

Question 37

What problems in SZ do deficits within the PFC and its connections with other areas of the brain (particularly the hippocampus) cause?

Answer 37

Cognitive symptoms

Question 38

Where is the hippocampus?

Answer 38

Temporal lobe

Question 39

What research is there for a difference in the hippocampus of people with SZ?

Answer 39

Conrad et al. (1991) - anatomical changes.

Question 40

What do deficits in the nerve connections between the hippocampus and the PFC correlate with?

Answer 40

The degree of working memory impairments, a central cognitive impairment in SZ (Mukai et al., 2015).

Question 41

What do Goto and Grace (2008) suggest that hippocampal dysfunction might aloso influence?

Answer 41

Levels of dopamine release in the basal ganglia, indirectly affecting the processing of information in the PFC.

Question 42

Grey matter link to SZ

Answer 42

SZ = reduced grey matter especially in temporal and frontal lobes.

Question 43

Ventricle size link to negative symptoms of SZ

Answer 43

Those with SZ, particularly those displaying negative symptoms, have enlarged ventricles (Hartberg et al., 2011).

Question 44

What is grey matter

Answer 44

Mostly dead cell bodies and unmyelinated axons.

Question 45

What are enlarged ventricles said to be a consequence of?

Answer 45

A consequence of nearby parts of the brain not developing properly or being damaged.

Question 46

What did Cannon et al. (2014) find about grey matter and ventricles in individuals at high clinical risk who developed SZ compared to those who did not develop SZ?

Answer 46

Found that individuals at high clinical risk who developed SZ showed a steeper rate of grey matter loss and a greater rate of expansion of brain ventricles compared to those who did not develop SZ.

Question 47

What are ventricles in the brain?

Answer 47

Brain cavities filled with cerebrospinal fluid.

Question 48

What is white matter?

Answer 48

Made up of nerve fibres covered in myelin.

Question 49

Where is white matter found?

Answer 49

Brain and spinal cord.

Question 50

What does myelin do?

Answer 50

Creates an insulating sheath around nerve fibres and helps to conduct information quickly through the CNS, enabling efficient information processing.

Question 51

What has research (e.g. Du et al., 2013) found about white matter in those with SZ?

Answer 51

Found reduced myelination of white matter pathways in schizophrenic patients, compared to healthy controls. This is particularly the case in the neural pathways between the PFC and the hippocampus.