nature and nurture Flashcards
What are the two main approaches to understanding developmental psychopathology?
- Clinical diagnostic approach: Treats psychopathologies as discrete categories, defined using criteria from diagnostic manuals (e.g., DSM-IV, ICD-10).
- Empirical quantitative approach: Views psychopathology symptoms as existing on a continuum; disorders are the extreme ends of a distribution
How are internalising and externalising psychopathologies classified?
- Internalising: Disorders directed inward (e.g., depression, anxiety).
- Externalising: Disorders expressed outwardly (e.g., conduct problems, ADHD).
Why is developmental psychopathology a major public health concern in youth?
High prevalence (10–25%)
Early onset (75% before age 25)
Chronic nature (22–46%, up to 60% in youth)
Early intervention/prevention opportunities
Why study the role of nature and nurture in developmental psychopathology?
- Understand origins/course of disorders
- Improve diagnostic clarity
- Predict genetic risk factors
- Inform treatment & prevention (e.g., drug targets, protective environments)
What are the key genetically informative research designs used to study nature vs. nurture?
- Twin design (MZ vs DZ twins)
- Adoption design (adoptive vs biological family effects)
- Twins reared together vs. apart
What are MZ and DZ twins and why are they useful in psychopathology research?
- MZ twins (identical): Share 100% of genes
- DZ twins (fraternal): Share ~50% of genes
- Comparison reveals genetic vs environmental contributions to traits.
What does the ACE model stand for in twin research?
- A (Additive genetic factors): Heritability
- C (Common/Shared environment): Environmental influences making twins similar
- E (Non-shared environment): Environmental influences making twins different Phenotype (P) = A + C + E**
How are ACE components calculated using twin correlations?
A = 2(rMZ – rDZ)
C = rMZ – A
E = 1 – rMZ
Using twin study data (rMZ = 0.42, rDZ = 0.28), estimate A, C, and E.
A = 2(0.42 – 0.28) = 0.28
C = 0.42 – 0.28 = 0.14
E = 1 – 0.42 = 0.58
What are heritability estimates for ADHD and depression in children?
- ADHD: A ≈ 90% (high heritability)
- Depression: A ≈ 30% (moderate heritability)
(Source: Bienvenu et al., 2011)
What are the two subtypes of antisocial behaviour (AB) in children?
- AB with Callous–Unemotional traits (AB/CU+)
* Lack of empathy, guilt, shallow affect
2.AB without CU traits (AB/CU−)
* May be influenced by different risk factors
Why is it important to study heterogeneity within disorders like antisocial behaviour?
Different subtypes (e.g., AB/CU+ vs AB/CU−) may have different genetic and environmental influences and respond to different interventions
What is comorbidity and what are examples in developmental psychopathology?
Comorbidity: Co-occurrence of two or more disorders
Examples:
* Depression and anxiety
* ADHD and conduct problems
* Reading and math disabilities
What does comorbidity suggest about the origins of developmental disorders?
Shared genetic and/or environmental risk factors may underlie multiple disorders.
What did Kendler et al. (1992) find about genetic overlap between depression and anxiety?
Major Depression: A = 42%, E = 58%
Generalized Anxiety: A = 31%, E = 69%
Genetic correlation (rA) = 1.0 (shared genetic influences)
Non-shared environmental correlation (rE) = 0.51
What does it mean to say that psychopathologies are polygenic?
- Multiple genetic variants contribute to risk
- Each variant has a small, additive effect
- Traits follow a bell-curve distribution
- No single “gene for” a disorder; many genes of small effect involved
How much of the human genome varies between people?
Over 99% of DNA is identical across individuals
~1% of the genome varies (still millions of base pairs)
Summarize the key takeaways in developmental psychopathology.
Both genetic and environmental factors are crucial.
Comorbid disorders (e.g., anxiety & depression) often share genetic origins.
Psychopathologies are polygenic and multifactorial—shaped by many genes and environmental influences.
