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Biological Psychology – Biological Aetiology of Schizophrenia
What is the biological aetiology of schizophrenia?
Answer:
The biological aetiology of schizophrenia refers to the biological factors that may contribute to the development of the disorder or occur as a result of it. Earlier psychological theories suggested that schizophrenia was caused by environmental influences, such as cold or detached parenting. However, this explanation has largely been replaced by the diathesis–stress model and the biomedical approach, which recognise that schizophrenia develops through an interaction between genetic vulnerability (diathesis) and environmental stressors.
Although Biological Psychology focuses on biological explanations, it is important to remember that schizophrenia should be understood by considering biological, psychological, and environmental influences together.
How does heredity contribute to schizophrenia?
Answer:
Research suggests that schizophrenia has a genetic component.
Key findings include:
How do neurotransmitters contribute to schizophrenia?
Answer:
One of the main biological explanations is the dopamine hypothesis.
This theory states that schizophrenia is associated with abnormal dopamine activity.
Evidence supporting this theory includes:
How does cerebral activity contribute to schizophrenia?
Answer:
Individuals with schizophrenia often display hypofrontality, meaning there is reduced activity in the prefrontal cortex compared with individuals without schizophrenia.
Changes in cerebral activity include:
How do changes in cerebral structure contribute to schizophrenia?
Answer:
Brain imaging studies using CT and MRI scans have identified several structural differences in individuals with schizophrenia.
These include:
What other biological factors are associated with schizophrenia?
Answer:
Several additional biological factors have been linked to schizophrenia.
These include:
What are the main biological factors associated with schizophrenia?
Answer (Note Form):
Heredity
Physiology – Neurotransmitters
Cerebral Activity
Cerebral Structure
Other Biological Factors
Why is the diathesis–stress model important in schizophrenia?
Answer:
The diathesis–stress model explains schizophrenia as the result of an interaction between biological vulnerability (genetic predisposition) and environmental stressors. This model suggests that having a genetic risk alone is usually not enough to develop schizophrenia. Instead, environmental factors, such as stressful life events, interact with biological vulnerability to trigger the disorder.
Conclusion
The biological aetiology of schizophrenia includes several interacting factors, including genetic predisposition, dopamine imbalance, hypofrontality, structural brain abnormalities, and other biological influences such as paternal age, Rh incompatibility, vitamin D deficiency, prenatal malnutrition, viral exposure, and season of birth. Although biological factors increase an individual’s vulnerability to schizophrenia, they do not act alone. The diathesis–stress model provides the most comprehensive explanation by recognising that schizophrenia develops through the interaction of biological predisposition and environmental stressors. Therefore, schizophrenia is best understood using a biopsychosocial approach, which considers biological, psychological, and environmental influences together.
What is the biological aetiology of schizophrenia?
Answer:
The biological aetiology of schizophrenia refers to the biological factors that may contribute to the development of the disorder or occur as a result of it. Earlier psychological theories suggested that schizophrenia was caused by environmental influences, such as cold or detached parenting. However, this explanation has largely been replaced by the diathesis–stress model and the biomedical approach, which recognise that schizophrenia develops through an interaction between genetic vulnerability (diathesis) and environmental stressors.
Although Biological Psychology focuses on biological explanations, it is important to remember that schizophrenia should be understood by considering biological, psychological, and environmental influences together.
How does heredity contribute to schizophrenia?
Answer:
Research suggests that schizophrenia has a genetic component.
Key findings include:
- Schizophrenia has been linked to most chromosomes, except chromosomes 3, 12, 14, 16, 17, 19, 20, 21, and Y.
- Monozygotic (identical) twins are more likely to both develop schizophrenia than dizygotic (fraternal) twins.
- However, the concordance rate for identical twins remains below 50%.
- There is a genetic predisposition to schizophrenia.
- Genetics alone do not cause schizophrenia.
- Environmental and psychological factors also contribute to its development.
How do neurotransmitters contribute to schizophrenia?
Answer:
One of the main biological explanations is the dopamine hypothesis.
This theory states that schizophrenia is associated with abnormal dopamine activity.
Evidence supporting this theory includes:
- Dopamine receptor blockers reduce schizophrenia symptoms.
- Clozapine works by blocking dopamine receptors in the nucleus accumbens.
- Hypofrontality increases dopamine activity, which may contribute to symptoms.
How does cerebral activity contribute to schizophrenia?
Answer:
Individuals with schizophrenia often display hypofrontality, meaning there is reduced activity in the prefrontal cortex compared with individuals without schizophrenia.
Changes in cerebral activity include:
- Reduced activity in the prefrontal cortex.
- Increased dopamine metabolism in the nucleus accumbens.
- Thinking
- Decision-making
- Emotional regulation
- Behaviour
How do changes in cerebral structure contribute to schizophrenia?
Answer:
Brain imaging studies using CT and MRI scans have identified several structural differences in individuals with schizophrenia.
These include:
- Loss of brain grey matter.
- Enlargement of the brain ventricles due to brain atrophy.
- Reduced volume of dendrites and axons.
- Smaller anterior hippocampus.
- Larger lateral ventricles.
- Larger third ventricle.
- A greater number of dopamine receptors in the brains of individuals with schizophrenia.
What other biological factors are associated with schizophrenia?
Answer:
Several additional biological factors have been linked to schizophrenia.
These include:
- Older paternal age (older fathers have a higher likelihood of having children who develop schizophrenia).
- Season of birth, with more individuals being born in late winter or early spring.
- Rh incompatibility, where the mother is Rh-negative and the baby is Rh-positive, possibly causing the mother’s immune system to attack the developing foetus.
- Vitamin D deficiency.
- Prenatal malnutrition.
- High population density.
- Exposure to viral epidemics during development.
- Living further from the equator.
What are the main biological factors associated with schizophrenia?
Answer (Note Form):
Heredity
- Genetic predisposition.
- Linked to most chromosomes.
- Higher concordance in identical twins than fraternal twins.
- Concordance remains below 50%, showing other factors are involved.
Physiology – Neurotransmitters
- Dopamine hypothesis.
- Abnormal dopamine activity contributes to schizophrenia.
- Dopamine receptor blockers reduce symptoms.
- Clozapine blocks dopamine receptors in the nucleus accumbens.
- Hypofrontality increases dopamine levels.
Cerebral Activity
- Hypofrontality (reduced activity in the prefrontal cortex).
- Increased dopamine metabolism in the nucleus accumbens.
- Affects thinking, planning, and emotional regulation.
Cerebral Structure
- Loss of grey matter.
- Enlarged ventricles due to brain atrophy.
- Reduced dendrite and axon volume.
- Smaller anterior hippocampus.
- Larger lateral and third ventricles.
- Increased dopamine receptors found during autopsy.
Other Biological Factors
- Older paternal age.
- Birth in late winter or early spring.
- Rh-negative mother with Rh-positive baby.
- Vitamin D deficiency.
- Prenatal malnutrition.
- High population density.
- Viral epidemics.
- Greater distance from the equator.
Why is the diathesis–stress model important in schizophrenia?
Answer:
The diathesis–stress model explains schizophrenia as the result of an interaction between biological vulnerability (genetic predisposition) and environmental stressors. This model suggests that having a genetic risk alone is usually not enough to develop schizophrenia. Instead, environmental factors, such as stressful life events, interact with biological vulnerability to trigger the disorder.
Conclusion
The biological aetiology of schizophrenia includes several interacting factors, including genetic predisposition, dopamine imbalance, hypofrontality, structural brain abnormalities, and other biological influences such as paternal age, Rh incompatibility, vitamin D deficiency, prenatal malnutrition, viral exposure, and season of birth. Although biological factors increase an individual’s vulnerability to schizophrenia, they do not act alone. The diathesis–stress model provides the most comprehensive explanation by recognising that schizophrenia develops through the interaction of biological predisposition and environmental stressors. Therefore, schizophrenia is best understood using a biopsychosocial approach, which considers biological, psychological, and environmental influences together.
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