L02 - Research Methods in Psychopathology

Question 1

What are the three different types of longitudinal studies?

Answer 1

retrospective

follow-up

high risk

Question 2

What are retrospective studies?

Answer 2

collect a sample of people with a disorder

try to determine what preceded it

self-report
existing archival data

Question 3

What are follow-up studies?

Answer 3

follow people with the disorder over time

see what happens to them

already-ill sample

difficult to derive etiological explanations

Question 4

What are high risk studies?

Answer 4

variant of follow-up

identify people who are likely to develop a disorder
- offspring of people with a disorder (genetic)
- on the basis of a biological abnormality
- behavioural variable

follow them over time

Question 5

What are the cons of high risk studies?

Answer 5

genetic: need to find people who have the disorder and also have children

biological: associations not well-proven

behaviours: may be a risk factor, or may be early manifestation of the disease

Question 6

What is a vulnerability marker?

Answer 6

should be trait-like, not state-related

has to be correlated with the disorder, but has to persist beyond the end of the episode
- could be a scar

has to be present in a high-risk population

pre-dat disorder

Question 7

What is the sample issue “case control v. cohort”?

Answer 7

case control: compare one group of people with disorder to a second group without the disorder

cohort: a single large sample of people, some of whom have the disorder

Question 8

What is the sample issue “patients vs. community”?

Answer 8

patient populations not representative of people with the disorder in the community

clinical populations tend to be more severe, have more comorbidities, more likely to be female, chronic

general population, get a sense of disorder “in the wild”

very expensive

Question 9

What is the sampling issue with controls?

Answer 9

healthy controls (HC) or Psychiatric controls (PC)?

match on potential confounds?

how do you match on lab tasks?

Question 10

How do family studies work?

genetic epidemiology

Answer 10

first step:
- identify proband
- assess family members
– interview (Family Study)
– informant report (Family History Study)

many disorders do run in families

subthreshold/symptoms

coaggregation

suggest genetic role, does not prove it

Question 11

How do adoption studies work?

genetic epidemiology

Answer 11

parent as proband

adoptee as proband

cross-fostering design
- adoption rare event
- selective placement

Question 12

How do Twin Studies work?

genetic epidemiology

Answer 12

monozygotic (Mz)
dizygotic (Dz)

A = additive genetic component
C = common environment component
E = unique environment

A = 2(rMz - rDz)

Mz concordance = 50%
Dz concordance = 25%
Difference (D) = 25%
2D = 50%

sample specific
higher with less environmental variance

Question 13

What are the problems with twin studies?

Answer 13

Mz twins often share placenta

Mz twins treated more similarly to one another

Heritability = estimated genetic contirbutions to observed phenotype

not deterministic

often don’t model G x E

Question 14

What are gene-environment correlations (rGE)?

Answer 14

Passive
- can be addressed in adoption studies

active (niche-picking)

evocative (reactive)
- active and evocative hard to measure - need better understnading of how environment shapes traits

Currently, all rGE attributed to G

caution when interpreting genetic contributions

Question 15

What is the paradox of intelligence?

Answer 15

IQ highly heritable: 80% (approx.)

IQ also malleable
- Flynn effect:
– developing countries

Higher IQ = seek out “more stimulating” environment
- more stimulating environments available with more development

Question 16

Heritability varies as a function of what?

Answer 16

heritabiltiy varies as a function of environment
- heritability of IQ increases across development
- among affluent families, heritability of IQ estimated at 0.72
– among less affluent families, little observed additive genetic influence (heritability of 0.10)
- heritability of **alcohol use ** for those residing in a neighbourhood with ten or more alcohol outlets was 74% compared with 16% for those in a neighbourhood with zero outlets
- eating disorder symptoms show minimal heritability before puberty but significant genetic effects (i.e., greater than 50%) during and after puberty

Question 17

What are quantitative genetics?

mode of transmission

Answer 17

single-gene transmission

polygenic transmission

mixed transmission

Question 18

What are the problems with single-gene transmission?

Answer 18

single dominant gene, woud expect 50% of relatives to have disorder

no psychiatric disorders show these rates of familial transmission

possible single-gene transmission
- expressed differently in different relatives

no strong evidence

Mendelian disorders very rare
- prevalence about 1 in 10,000

most psychiatric disorders hae prevalence rates at least .5%

monogenic disorders - distinct from “normal”
- e.g., Parkinson’s

psychiatric disorders dimensional, continuously distributed

Question 19

What is polygenic transmission?

Answer 19

psychological phenotypes likely controlled by more than 1 gene
- skin colour - at least 3 genes
- can be modified by GxG interactions
- GxE interactions

action of multiple genes
- additive or interactive effects

Question 20

What are some missing heritabilities?

Answer 20

Big Five personality traits have heritability estimates of 0.40 to 0.60

autism spectrum disorder currently estimated at 0.38

schizophrenia at 0.64

estimates so high, explanations provided in quantitative genetics explains very little

where do we get the remaining genetion variation?

Question 21

What are gene environment interactions?

Answer 21

notion that adverse effects of genes on mental health only expressed under certain environmental conditions

Question 22

What are epigenetics?

Answer 22

regulation and expression of genes

DNA

action of genes can be regulated

some genes “turn on” at certain developmental periods

under certain environmental circumstances

alterations heritable

Question 23

What did Michael Meaney study on rats contribute to epigenetics?

Answer 23

good rat mothering associated with better functioning of neuroendocrine stress response

bad rat mothering = high levels of stress and cortisol

cross-fostering

changes in glucorticoid receptor gene

only evident when switch occurred early

Question 24

What are genotypes-endophenotypes-phenotypes?

Answer 24

genotype –> phenotype

phenotypes very complex phenomena, multiply-determined, often poorly defined

endophenotype: intermediate step between microscopic genes and nerve cells and the experiential and psychological phenotype
- must segregate with illness in the population
- must be heritable
- must not be state-dependent (i.e., manifests whether illness is active or in remission)
- must co-segregate with illness within families
- must be present at a higher rate within affected families than in the population
- must be amenable to reliable measurement, and be specific to the illness of interest