The Explanation
- Schizophrenia has a strong genetic component.
- Monozygotic (identical) twins have a higher concordance rate for schizophrenia as compared to dizygotic (fraternal) twins.
- Gottesman and Shields analyzed 24 sets of MZ twins and 33 sets of DZ twins from a sample of 467 twins registered at a hospital in London. They found that around 50% of MZ twins shared a schizophrenic status, while only about 9% of DZ twins did.
- Genome-wide association studies (GWAS) have identified multiple gene variants associated with schizophrenia.
- Schizophrenia is a polygenic condition, meaning it involves thousands of gene variants.
- Many of the genes linked to schizophrenia are involved in the synthesis, transportation, and breakdown of neurotransmitters like dopamine.
- DiGeorge syndrome, which involves a deletion on chromosome 22, increases the risk of developing schizophrenia.
- In this syndrome, the COMT gene, which codes for an enzyme involved in dopamine breakdown is found to be deleted.
- Another gene, the DISC1 gene may increase the risk of schizophrenia by affecting the neurotransmitter GABA, which regulates dopamine activity.
Relevant Issues and Debates
Individual and Situational Explanations
- Genetic explanation is purely individual
- Strengths
- When comparing identical and non-identical twins, higher schizophrenia rates in identical twins suggest genetic influence, guiding prevention of the disorder;
- DiGeorge syndrome with COMT gene deletion links to increased risk of schizophrenia, encouraging genetic testing for early identification
- Weaknesses
- Genes are important, but not enough to explain schizophrenia. Other factors are involved too, such as cognitive style;
- Schizophrenia genetics are complicated, with many genes involved, making it hard to understand the disorder through genes alone
Nature versus Nurture
Genetic explanation supports only nature
- Strengths
- When comparing identical and non-identical twins, higher schizophrenia rates in identical twins suggest genetic influence, guiding prevention of the disorder;
- DiGeorge syndrome with COMT gene deletion links to increased risk of schizophrenia, encouraging genetic testing for early identification.
- Weaknesses
- Genes and the environment work together. Genetic differences can be affected by environmental factors like stress or trauma;
- MZ twins are treated more similarly than DZ twins by parents because of their same gender and appearance, so it’s hard to tell if differences are from genes or environment
Reductionism versus Holism
Genetic explanation is reductionist
- Strengths
- Focusing on specific genes such as COMT in schizophrenia helps us understand its genetic causes better and find targeted treatments such as those reducing dopamine levels;
- Finding specific genes for measurement like COMT and DISC1 helps scientific investigation and knowledge advancement about role of genes in schizophrenia
- Weaknesses
- Focusing on genes and chemicals oversimplifies schizophrenia, ignoring its complexity with cognitive,environmental and social factors;
- Reducing schizophrenia to genes overlooks the impact of stress, trauma, substance abuse, and social factors on the disorder, reducing generalizability
Determinism versus Free Will
- Genetic Explanation is determinist
- Strengths
- Genes play a big role in schizophrenia based on studies of families and twins. DNA determines susceptibility, reducing the tendency to blame the individual;
- COMT and DISC gene variations are linked to schizophrenia, showing a genetic tendency for the disorder. Thus, genetic risk can be controlled to prevent the disorder
- Weaknesses
- Schizophrenia is caused by many genes working together, but no single gene determines it completely. This challenges the deterministic explanation;
- Schizophrenia is not only influenced by genes but also by environmental factors like stress or trauma, making the explanation reductionist.
Idiographic versus Nomothetic
- Strengths
- Large-scale studies like family, twin, and genome-wide association studies have found strong evidence for role of genes in schizophrenia, increasing validity;
- Data has been gathered in these studies from very large and diverse samples, increasing generalizability to populations.
- Weaknesses
- Nomothetic approach ignores personal experiences and individual differences in schizophrenia’s development and symptoms;
- Nomothetic approach oversimplifies complex factors in schizophrenia, ignoring how genetics, environment, and psychology interact to cause the disorder.
search terms – a levels psychology; schizophrenia, Gottesman and Shields, genetic explanation of schizophrenia, COMT, DISC, 1.1.2, issues and debates, as and a psychology; psychology and organizations; paper 3; paper 4; igcse psychology; application to everyday life; strengths of application to everyday life; weaknesses of application to everyday life; gcse psychology; cie psychology; cambridge 12 psychology; a2 psychology; new syllabus; 2024-26 syllabus; 2024 9990 syllabus; 9990 curriculum; new 9990 syllabus; 9990 psychology