WEEK 5 - 2: Nature and Nurture

Developmental psychopathology

• different approaches

  • clinical diagnostic approach

    • by someone profesionally trained

    • consider frequency of symptoms before diagnosis

  • emperical quantitative approach

    • continuous scale used to measure mental health problems

    • can still used a clinical cutoff

    • disorders at extreme ends of the distribution

• classification

  • internalising - feelings, emotions (anxiety)

  • externalising - bhv (attentional problems)

Psychopathology in children and youth

• major public health issue

• 10-25% depending on categories of population

• have early onset - 75% before 25y

• chronic/ long lasting - 60% in young people, 22-46%

• a lot of work going to early intervention

Study of nature and nurture

• origins and causes of psychopathologies

• why things overlap?

• genetics involved?

• interactions with environment?

• predictions and treatments/ preventions - new drug targets and interventions found/ created

• risk reduction interventions

Twin design

• phenotypic variation (P) : observed variable

  • heritability (A, h2): influences of genetic factors

  • Shared environment (C, c2): any environmental influences that contribute to the similarity between co-twins

  • non-shared environment(E, e2): any aspect of environmental influences that makes twins different from each other

• P = h2 + c2 + e2

• heritability (A) = 2(rMZ - rDZ)

• Shared environment (C) = rMZ - h2

• Non-Shared environment (E) = 1 - rMZ

• ACE Model

  • structure approaching model used

  • presented as a path diagram

  • A - additive

  • C - common environmental effects

  • E - non-shared environmental effects

Sub-types of antisocial bhv

• children w/ onset early antisocial bhv

• group w/ callous-unemotiona traits (CU)

• group w/out CU

• results

  • more genetically influenced

Co-occurence/ Comorbidity

• co-occurence of two different disorders/ disabilities

• both can be observed at the same time:

  • depression and anxiety

  • ADHD with language problems

  • reading disability with mathematics disability

ACE Models

• separate estimation of genetic A and environmental C-shared, E-nonshared enfluences

• assumptions - equal environments

Genetic Variation

• what contributed to individual differences and bhvl traits?

• humane genome is built with 3 billion base pairs

• 20-25%

• more tha 99% od the DNA sequence is the same for everybody

• only 1% of the DNA sequence is variable

Pathologies are polygenic traits

• psychopathologies are influenced by polygenic traits - like skin colour

• each genetic variant is additive to the others: more specific genetic variants (alleles) - higher risk of psychopathology