Schizophrenia- Biological explanation

Question 1

Neural correlates

Answer 1

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 2

Dopamine

Answer 2

A neurotransmitter that generally has an excitatory effect and is linked to the sensation of pleasure.

Question 3

Family studies- Gottesman et al

Answer 3

Gottesman et al found a positive correlation between genetic similarity and the likelihood of developing schizophrenia. He found that monozygotic twins had a 48% chance of developing schizophrenia, dizygotic had 17% and siblings have a 9% chance.

Question 4

Candidate genes- Ripke et al

Answer 4

Ripke et al. (2014) combined all previous data from genome-wide studies of schizophrenia. The genetic make-up of 37,000 people with a diagnosis of schizophrenia was compared to that of 113,000 controls, 108 separate genetic variations were associated with slightly increased risk of schizophrenia. Schizophrenia is aetiologically heterogeneous, i.e., different combinations of factors, including genetic variation, can lead to the condition.

Question 5

Mutation of genes- Brown et al

Answer 5

Evidence for mutation comes from positive correlations between paternal age (associated with increased risk of sperm mutation) and risk of schizophrenia, increasing from around 0.7% with fathers under 25 to over 2% in fathers over 50

Question 6

Supporting research evidence

Answer 6

Adoption studies such as Pekka Tienari et al. (2004), show that biological children of parents with schizophrenia are at heightened risk even if they grow up in an adoptive family.

A recent twin study by Rikke Hilker et al. (2018) showed a concordance rate of 33% for identical twins and 7% for non-identical twins.

This shows that some people are more vulnerable to schizophrenia as a result of their genetic make-up.

Question 7

Environmental factors

Answer 7

Biological risk factors include birth complications (Morgan et al. 2017) and smoking THC-rich cannabis in teenage years (Di Fortiet al. 2015).

In one study by Nina Morkved et al. (2017), 67% of people with schizophrenia and related psychotic disorders reported at least one childhood trauma as opposed to 38% of a matched group with non-psychotic mental health issues.

This means that genetic factors alone cannot provide a complete explanation for schizophrenia.