Schizophrenia-Biological Explanation

Question 1

Genetics -

Answer 1

Genes consist of DNA strands. DNA produces ‘instructions’ for general physical features of an organism (such as eye colour, height) and also specific physical features (such as neurotransmitter levels and size of brain structures). These may impact on psychological features (such as intelligence and mental disorder). Genes are transmitted from parents to offspring, i.e. inherited.

Question 2

Dopamine -

Answer 2

A neurotransmitter that generally has an excitatory effect and is associated with the sensation of pleasure. Unusually high levels are associated with schizophrenia and unusually low levels are associated with Parkinson’s disease.

Question 3

Dopamine -

Answer 3

A neurotransmitter that generally has an excitatory effect and is associated with the sensation of pleasure. Unusually high levels are associated with schizophrenia and unusually low levels are associated with Parkinson’s disease.

Question 4

Neural correlates -

Answer 4

Patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience.

Question 5

Genetic Basis of Schizophrenia

Answer 5

Schizophrenia runs in families, suggesting a genetic link, although family members also share similar environments. Systematic studies show that greater genetic similarity between family members increases the likelihood of both developing schizophrenia.

Question 6

What did Irving Gottesman’s (1991) study reveal about genetic similarity and schizophrenia?

Answer 6

Gottesman’s large-scale family study found a strong relationship between the degree of genetic similarity and the shared risk of schizophrenia.

Question 7

Candidate Genes

Answer 7

Candidate genes are specific genes believed to increase the risk of inheriting schizophrenia. Schizophrenia is polygenic, meaning it involves multiple genes, and aetiologically heterogeneous, meaning different combinations of factors can lead to the condition.

Question 8

What did Stephen Ripke et al. (2014) find in their genome-wide study on schizophrenia?

Answer 8

Ripke’s study analyzed the genetic data of 37,000 people with schizophrenia and 113,000 controls, identifying 108 genetic variations associated with increased risk, including genes involved in neurotransmitter function like dopamine.

Question 9

Dopamine Hypothesis

Answer 9

Neurotransmitters, especially dopamine, are believed to function differently in the brain of a person with schizophrenia. Dopamine is essential in brain systems related to schizophrenia symptoms.

Question 10

What role does dopamine play in schizophrenia?

Answer 10

Dopamine affects several brain areas involved in schizophrenia symptoms, with abnormalities in dopamine levels associated with different symptoms.

Question 11

Hyperdopaminergia in the Subcortex

Answer 11

The original dopamine hypothesis focused on hyperdopaminergia, or high dopamine levels, in the subcortex. For example, excess dopamine receptors in Broca’s area may be linked to poverty of speech or auditory hallucinations.

Question 12

How does hyperdopaminergia in Broca’s area relate to schizophrenia symptoms?

Answer 12

High dopamine levels in Broca’s area, which controls speech production, may contribute to symptoms like auditory hallucinations and reduced speech.

Question 13

Hypodopaminergia in the Cortex

Answer 13

More recent dopamine hypotheses suggest hypodopaminergia, or low dopamine levels, in the cortex. Goldman-Rakic et al. (2004) linked low dopamine in the prefrontal cortex to negative symptoms.

Question 14

What symptoms might result from hypodopaminergia in the prefrontal cortex?

Answer 14

Low dopamine levels in the prefrontal cortex, which controls decision-making and thinking, may cause negative symptoms like reduced motivation and impaired thought processes.

Question 15

Combined Dopamine Hypothesis

Answer 15

It is possible that both hyperdopaminergia (high dopamine levels) in the subcortex and hypodopaminergia (low dopamine levels) in the cortex contribute to schizophrenia.

Question 16

How might both high and low dopamine levels explain symptoms of schizophrenia?

Answer 16

High dopamine in certain brain areas may cause positive symptoms like hallucinations, while low dopamine in other regions may cause negative symptoms like lack of motivation.

Question 17

Neural Correlates of Schizophrenia

Answer 17

Neural correlates are brain structures or functions that are associated with certain experiences, such as symptoms of schizophrenia. Both positive and negative symptoms have neural correlates.

Question 18

What are neural correlates in schizophrenia?

Answer 18

They are measurements of brain structure or function that correlate with schizophrenia symptoms, helping researchers understand the brain’s role in these experiences.

Question 19

Neural Correlates of Negative Symptoms (Avolition)

Answer 19

Avolition, a loss of motivation, involves the anticipation of reward. Abnormalities in the ventral striatum, which is involved in reward processing, may be linked to avolition.

Question 20

What did Juckel et al. (2006) find about activity levels in the ventral striatum in people with schizophrenia?

Answer 20

Juckel et al. found lower activity levels in the ventral striatum in schizophrenia patients, with a negative correlation between ventral striatum activity and the severity of negative symptoms.

Question 21

What did Juckel et al. (2006) find about activity levels in the ventral striatum in people with schizophrenia?

Answer 21

Juckel et al. found lower activity levels in the ventral striatum in schizophrenia patients, with a negative correlation between ventral striatum activity and the severity of negative symptoms.

Question 22

Neural Correlates of Positive Symptoms (Auditory Hallucinations)

Answer 22

Positive symptoms, such as auditory hallucinations, also have neural correlates. Allen et al. (2007) scanned the brains of people experiencing auditory hallucinations.

Question 23

What neural correlates did Allen et al. (2007) identify in people with auditory hallucinations?

Answer 23

They found lower activation in the superior temporal gyrus and anterior cingulate gyrus, with the hallucination group making more errors than controls, suggesting these brain areas are involved in auditory hallucinations.

Question 24

Genetic Susceptibility in Schizophrenia
Gottesman

Answer 24

There is substantial evidence from various sources supporting a genetic vulnerability to schizophrenia.

Question 25

What did Gottesman’s study reveal about genetic similarity and schizophrenia risk?

Answer 25

Gottesman’s study showed a strong correlation between genetic similarity and schizophrenia risk, indicating that genetic factors significantly increase vulnerability.

Question 26

Tienari et al. (2004) Adoption Study

Answer 26

Adoption studies by Tienari et al. (2004) showed that children of schizophrenia sufferers are at heightened risk of schizophrenia even if adopted into families without a history of the disorder.

Question 27

What does Tienari et al.’s study suggest about schizophrenia risk?

Answer 27

It suggests that genetic factors contribute to schizophrenia risk independently of family environment.

Question 28

Ripke et al. (2014) Molecular Level Study

Answer 28

Ripke et al. found that specific genetic variations at the molecular level significantly increase the risk of schizophrenia.

Question 29

How does Ripke et al.’s study support genetic susceptibility in schizophrenia?

Answer 29

It provides molecular evidence that certain genetic variations are associated with an increased risk of developing schizophrenia.

Question 30

Mixed Evidence for the Dopamine Hypothesis

Answer 30

There is mixed evidence supporting the dopamine hypothesis, which suggests abnormal dopamine functioning in schizophrenia.

Question 31

How do dopamine agonists and antipsychotic drugs provide evidence for dopamine’s role in schizophrenia?

Answer 31

Dopamine agonists increase dopamine levels, worsening symptoms, while antipsychotic drugs reduce dopamine activity, alleviating symptoms, suggesting dopamine involvement.

Question 32

Lindstroem et al. (1999) Radioactive Labelling Study

Answer 32

Lindstroem et al. (1999) used radioactive labelling to show that chemicals needed to produce dopamine are taken up faster in the brains of people with schizophrenia, suggesting higher dopamine production.

Question 33

What does Lindstroem et al.’s study suggest about dopamine levels in schizophrenia?

Answer 33

It indicates that people with schizophrenia may produce more dopamine than controls, supporting the dopamine hypothesis.

Question 34

Limitations of the Dopamine Hypothesis

Answer 34

While dopamine is a key factor, it does not fully explain schizophrenia. Genes identified in Ripke et al.’s study also code for other neurotransmitters, such as glutamate.

Question 35

What role does glutamate play in current schizophrenia research?

Answer 35

Glutamate is being investigated as an important neurotransmitter in schizophrenia, alongside dopamine, as suggested by research from Moghaddam and Javitt (2012).

Question 36

Correlation-Causation Problem in Neural Correlates

Answer 36

Neural correlates are brain abnormalities associated with symptoms of schizophrenia, but their existence does not prove causation.

Question 37

Why is there a correlation-causation issue in neural correlates of schizophrenia?

Answer 37

A correlation does not mean causation; abnormal brain activity might not cause symptoms directly and could result from or coexist with other factors.

Question 38

Example of Correlation-Causation in Ventral Striatum Activity

Answer 38

Lower activity in the ventral striatum correlates with negative symptoms, but it’s unclear if the activity reduction causes the symptoms or if the symptoms reduce activity.

Question 39

What alternative explanations exist for low ventral striatum activity in schizophrenia?

Answer 39

Reduced activity could be caused by negative symptoms themselves or by a third factor affecting both striatum activity and symptoms.

Question 40

The Role of Mutation

Answer 40

The Role of Mutation in Schizophrenia
Schizophrenia can occur even without a family history of the disorder.

Question 41

What is one explanation for cases of schizophrenia with no family history?

Answer 41

One explanation is DNA mutation in parental genes, especially in paternal sperm cells.

Question 42

Causes of DNA Mutation Leading to Schizophrenia

Answer 42

Mutations in parental DNA can be caused by factors like radiation, poison, or viral infection.

Question 43

What external factors can lead to DNA mutations that increase schizophrenia risk?

Answer 43

Radiation, poison, and viral infections can all lead to DNA mutations that may raise schizophrenia risk.

Question 44

Brown et al. (2002) Study on Paternal Age and Schizophrenia Risk

Answer 44

Brown et al. (2002) found a positive correlation between paternal age and schizophrenia risk.

Question 45

What did Brown et al. find about the relationship between paternal age and schizophrenia risk?

Answer 45

Schizophrenia risk increases with paternal age, from around 0.7% in fathers under 25 to over 2% in fathers over 50.

Question 46

Paternal Age and Risk of Schizophrenia

Answer 46

Older paternal age is associated with an increased risk of schizophrenia due to a higher likelihood of DNA mutations in sperm cells.

Question 47

How does paternal age affect schizophrenia risk?

Answer 47

As paternal age increases, the risk of sperm mutations rises, leading to a higher risk of schizophrenia in offspring.