Genetics Of Affective Disorders

Question 1

Describe the aetiology and treatment of depression

Answer 1

Predisposing factors/social stressor/precipitating factors/personality factors –> brain –> medication/talking therapies/social interventions

Question 2

Describe some of the methodological issues related to studies on mood disorders

Answer 2

Lack of operational diagnostic criteria

No biological measure of the diagnosis (based on symptoms)

Question 3

Describe the conclusions of some studies on depression including family studies, twin studies, adoption studies

Answer 3

Family studies - bipolar –> increase of bipolar and unipolar depression, unipolar –> increase of unipolar depression only
Twin studies - monozygotic twins –> 64% unipolar, 79% bipolar, lower for dizygotic (24%, 19%)
Adoption studies - adoptees from depressed biological parents have a greater risk than from healthy biological parents

Question 4

Describe the likely mode of transmission of mood disorders

Answer 4

One or a few major genes
Genes with a smaller effect size
Environmental factors

Question 5

Explain the two main forms of inheritance in affective disorders

Answer 5

SML - single major locus with variable penetrance
QTL - quantitative trait loci (loci contribute significantly to the variation in quantitative traits in the population) - a lot of genes contribute to a little role

Question 6

Explain the terms ‘linkage’ and ‘association’

Answer 6

Linkage - co-occurrence with a known disease and a known location is measured, used to identify possible areas of interest on chromosomes by using linkage to a known loci
Association - co-occurrence of an allele at a particular locus and a disease, systemic polymorphism detection, association studies of disease comparison

Question 7

Describe the link between genetics and environment

Answer 7

Can be additive
Can change a person’s sensitivity to traumatic events
Have an effect on people’s environment
Epigenetic changes in response to childhood maltreatment (methylation)

Question 8

Describe some of the reasons for sex differences in depression

Answer 8

Under reporting by men

Environmental factors - employment status, psychological factors

Question 9

Describe some of the causes of affective disorders

Answer 9

Predisposing - genetics, childhood experiences
Maintaining - social stressors, habits e.g. alcohol misuse
Precipitating - related to losses