Psychopathology Flashcards
What are the two approaches?
Clinical diagnostic
Empirical quantitative
Clinical diagnostic approach
Discrete categories defined on the basis of criteria proposed by expects (DSM-V)
Qualitative, used by professionals
Empirical quantitative approach
Assessed on a continuous scale, disorders at the extreme end of the distribution, indicates some may be more severe
Classification of psychopathologies
Internalising - depression, anxiety
Externalising - conduct problems, ADHD
Why are we interested in it?
It is a major public heath issue, 1 in 4 girls, 1 in 8 boys
Very common/prevalent - 10-25% depending on country
Early onset, 75% occur before 25
Chronic - high chance it will come back
Important period for prevention and intervention
How do we study nature and nurture?
Not possible to disentangle both but twin and adoption designs help make estimation of which
Twin designs
Compare similarity of MZ and DZ twins on a specific trait, allowing us to get a rough estimate of separate genetic and environmental contributions
MZ twins result from 1 fertilised egg, so 100% similar
DZ - 2 eggs, 50% similar
What are the components of phenotypic variation
Heritability H2 or A - genes
Shared environment C, c2 - only environmental influences that contribute to similarity of twins
Non shared environment E e2 - only aspect of environment that makes twins different
Why we study nature and nurture?
Need to understand origins and cause, to then identify who would be predicted to get it, treatment, prevention and risk reduction interventions
What is the equation for phenotypic variation?
P = H2 + C2 + E2
How to estimate H?
2(rMZ - rDZ)
How to estimate C?
rMZ - h2
How to estimate E?
1-rMZ
ACE model
ACE all explain the variance in a trait
components can be measured using structural model fitting analyses
What disorders are highly heritable?
Bipolar Schizophrenia Alzeimers Cocaine Anerexia Substance use: drugs, cannibis, alcohol ADHD - 90%
What disorders aren’t highly heritable?
Panic disorder
Anxiety
Depression - 30%
Nothing is 100% heritable, always some environmental input
What does heterogeneity of psychopathologies refer too
One psychopathology with loads of subtypes
Subtypes of anti social behaviour
Some children show callous unemotional traits (lacking guilt, empathy and shallow affect)
Study investigating callous unemotional traits
Using ACE, identified AB, CU+ and AB, CU-
Results: AB/CU+ is highly heritable - 80%
AB, CU- isn’t as high, 30% genes, 36% non shared and 34% shared environment
Findings confirmed when children were 12, CU+ leads to negative outcomes, low achievement and peer problems
What does comorbidity mean?
2 disorders at the same time
What disorders occur at the same time?
Depression and anxiety
ADHD and language, conduct problems
Reading disability and maths disability
What does comorbidity suggest?
Common factors between disorders
What are the genetic factors that contribute to anxiety and depression?
1, meaning all genetic factors are the same contributing
50% is environment, whether they get the disorder depends on their environment
What is genetic variation?
This contributes to individual differences in behaviour traits, human genome is built with 3 billion pairs, 20-25,000 genes. More than 99% of DNA is the same for everyone, only 1% is variable
Have they found regions of DNA which vary between people?
No, the search is still in progress
What are polygenic traits?
When psychopathologies are influenced by more than one genetic variant
Each genetic variant is additive to the others: more specific genes = higher risk
What are psychopathologies?
Polygenic - multiple genes
Multifactorial - environment
