L3 Biological Explanation for SZ - Genetics

Question 1

What is the Genetic Explanation for SZ?

Answer 1

• The idea that SZ is heritable/inherited through generations via transmission of genes and DNA
• This is usually tested through family, twin and adoption studies by checking the concordance rate of the illness

Question 2

Candidate Gene Study?

Answer 2

• Ripke et al (2014)
  
  • SZ might be polygenic where a number of candidate genes might be responsible for the illness
  • Conducted a meta-analysis of studies that looked into candidate genes of SZ sufferers
  • 37,000 SZ sufferers were compared to 11,000 controls
  • He found that 108 seperate genetic variations were associated with increased risk of SZ
  • These genes seemed to code for the neurotransmitter dopamine, increased dopamine can cause SZ

Question 3

Family Study?

Answer 3

• Gottesman (1991)
  
  • If both parents had SZ, the likelihood of the offspring having it was 46%
  • If one parent had SZ then the likelihood dropped to 13%
  • If a sibling has SZ then the likelihood of SZ was 9%

Question 4

Twin Study?

Answer 4

• Gottesman (1991)
  
  • MZ twins should have a higher concordance rate of SZ than DZ twins if there is said to be a genetic component
  • Gottesman found a 48% concordance rate for MZ twins and a 17% concordance rate for DZ twins.

Question 5

Adoption Study?

Answer 5

• Tienari et al (2001)
  
  • Carried out a study in Finland of 164 adoptees who’s biological mother was a sufferer of SZ
  • It was found only 11 were diagnosed with SZ compared to a control group of 197 where only 4 were diagnosed

Question 6

.

Answer 6

.

Question 7

Strengths of Genetic Explanations of SZ? (1)

Answer 7

• Wealth of Research
  
  • Lots of evidence to support the Genetic Basis, through Gottessman, Ripke and Tienaris studies
  • Shows that if a child grows up in a family where their biological parents had SZ there is a heightened chance of them getting it
  • Suggests there is a genetic basis and explanation for SZ

Question 8

• Weaknesses of Genetic Explanations of SZ? (3)

Answer 8

Biological Reductionism
Nature or Nurture
Diathesis Stress Model

Question 9

Biological Reductionism (-)

Answer 9

• Does not account for other psychological/cognitive factors
• Family Dysfunction etc

Question 10

Nature and Nurture (-)

Answer 10

• It is hard to distinguish between nature and nurture in the case of SZ
• With MZ twins for example, they are usually sent to the same school, raised the same way, nurtured in a similar manner
• This then makes it difficult to separate genes from environmental factors
• Even in adoption studies children are usually adopted by parents who would rear them similarly to their biological parents

Question 11

Diathesis Stress Model (-)

Answer 11

• Genetic Vulnerability is only triggered if there is a stress-trigger in ones life
• You may be born with a gene which makes you vulnerable to SZ but if your life is stress free you may not have the disorder at all
• Genetic factors alone may not trigger SZ