Genetic Reason for Schizophrenia

Question 1

Hilker et al (2018)

Answer 1

Estimate for heritability of SZ is 79%

Question 2

Genetic Explanation

Answer 2

1% of population affected by SZ, BUT if you have first gen relatives with SZ likelihood increases. Hilker et al found heritability at 79%

Hilker et al.

DiGeorge Syndrome

COMT Gene

DISC1

Question 3

DiGeorge Syndrome

Answer 3

Cuased by the deletion of 30-40 genes in the region of Chromosome 22. 25% of people with DiGeorge Syndrome get SZ, thus these genes could be relevant to SZ.

COMT Gene is one of those deleted

Question 4

Genes linked to SZ

Answer 4

COMT Gene - This is deleted in DiGeorge Syndrome.
Related to regulation of dopamine levels, which can lead to SZ symptoms

DISC1 - Those with an abnormal DISC1 gne are 1.4x more likely to develop SZ (Kim et al. 2012). Codes for GABA, which regulates seratonin and dopamine

Question 5

Diathesis-Stress Model

Answer 5

Explanation that a disorder is the result of an interaction between genetic predisposition and stress.
E.g. stress could trigger the activation of the gene that they inherited

Question 6

Eval. of genetic explanation for SZ

2 Strengths, 2 Weaknesses

Answer 6

Strengths
- Gottesman & Shields (1966) found concordance rates of 42% for MZ, 9% for DZ

• Kim et al. (2012) found that an abnormal DISC1 gene increased SZ likelihood 1.4x. This codex for the NT GABA, which regulates dopamine and seratonin in the limbic system

Weaknesses
- Equal environments assumption. Joseph (2002) argues that MZ twins treated more similarly than DZ

• Concordance rate is far from 100%. Pedersen & Mortensen (2006) found that the longer a person is exposed to city life the greater the risk of SZ