Biological Explanations

Question 1

✅GENETICS: STRONG EVIDENCE FOR A GENETIC LINK -

Answer 1

• For example, Gottesman (1991) demonstrated that the closer the degree of genetic relatedness, the greater the risk of developing schizophrenia. Adoption studies, such as Tienari et al. (2004), further support this by showing that children of schizophrenia sufferers are at heightened risk of developing the disorder even when adopted into families with no history of schizophrenia.
• This provides overwhelming evidence that genetic factors increase susceptibility to the condition, highlighting the role of biological inheritance.
• However, while genetics appear to play a significant role, they may not be the only factor involved. Environmental influences, such as stress or family dynamics, likely interact with genetic vulnerability to trigger the onset of schizophrenia.
• This supports the validity of the involvement of genetics, but proposes a diathesis-stress model, where genetics create a predisposition that may require environmental factors to manifest fully.

Question 2

❌ GENETICS: EARLY ENVIRONMENT INFLUENCES CONTRIBUTE TO SCHIZOPHRENIA:

Answer 2

• For example, Morgan et al. (2017) found that birth complications increase the risk of developing schizophrenia.
  • Di Forti et al. (2015) showed that teenagers who smoke cannabis with high THC levels are also at heightened risk.
  • Morkved et al. (2017) reported that 67% of individuals with schizophrenia had experienced at least one childhood trauma, compared to only 38% in a control group.
• These findings suggest that environmental influences, such as early trauma or substance use, contribute significantly to the development of schizophrenia. Therefore, while genetics may create a vulnerability, they cannot provide a complete explanation.
• This underlines the validity of the genetic hypothesis in isolation; the interaction between genetic predisposition and environmental triggers supports a diathesis-stress model, indicating that schizophrenia is likely the result of both biological and external factors rather than genetics alone.

Question 3

✅DOPAMINE HYPOTHESIS: DOPAMINE DYSFUNCTION OFFERS AN EXPLANATORY FRAMEWORK:

Answer 3

• Kapur (2000) proposed the salience hypothesis as a means by which dopaminergic abnormalities may give rise to positive symptoms. Kapur suggests that dopamine, which typically codes salient events in the environment, and therefore serves as a learning signal, fires chaotically in schizophrenia, thereby rendering the learning signal aberrant, causing the patient to inappropriately imbue otherwise neutral events with abnormal significance.
• This suggests that delusional ideation results as an attempt to reconcile this.
• Therefore, the salience hypothesis provides a means by which to relate biological and clinical observations, which increases its validity.

Question 4

❌ DOPAMINE HYPOTHESIS: MIXED EVIDENCE FOR THE ROLE DOPAMINE IN SCHIZOPHRENIA

Answer 4

• It is consistent with the hypothesis, that amphetamines, which increase dopamine levels, can worsen schizophrenia symptoms or produce schizophrenia-like symptoms in non-sufferers. Also, antipsychotic drugs, which reduce dopamine, can alleviate symptoms in patients.
• However, Moncrieff (2009) argues that the evidence is inconclusive, as dopamine levels can be influenced by factors like stress and smoking. Also, Ripke et al. suggest that other neurotransmitters, such as glutamate, may also play a significant role in the disorder. Current research has shifted focus towards glutamate, demonstrated through studies using ketamine, a glutamate blocker, to model schizophrenia, as well as the role of cannabinoids like THC.
• This suggests that while dopamine may contribute to schizophrenia, it does not provide a complete explanation. This undermines the validity of a purely dopaminergic explanation, and suggests a more comprehensive understanding likely involves multiple neurotransmitters interacting, highlighting the complexity of the disorder’s biological basis.

Question 5

❌CORRELATIONAL STUDIES DON’T IDENTIFY THE CAUSE OF SCHIZOPHRENIA SYMPTOMS:

Answer 5

• For example, Juckel et al. (2006) found that lower ventral striatum activity is associated with negative symptoms such as avolition. However, this abnormal brain activity may be caused by other factors, such as trauma or environmental influences, rather than being the direct cause of schizophrenia.
• This makes it difficult to use correlational evidence to establish causation, as it cannot rule out other intervening variables that might influence both brain activity and symptoms.
• Therefore, while neural correlates provide useful insights into the biological basis of schizophrenia, they do not definitively explain its origins. This limits the application of this approach for treatments until further research determines whether abnormal brain activity is a cause or a consequence of the disorder, ensuring a clearer understanding of the relationship between neural structures and schizophrenia symptoms.