Gene/environment interactions in the development of mental health and illness Flashcards Preview

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Flashcards in Gene/environment interactions in the development of mental health and illness Deck (7):
1

What are gene-environment interactions?

- Gene-environment interaction (GxE) is a causal mechanism where one or more genetic variants and one or more environmental factors contribute to the causation of a condition in the same individual.

- In a GxE, the genetic factors influence the sensitivity to environmental exposures.

- GXE are distinguished from gene-environment correlations, where genetic factors influence the probability of environmental exposures.

2

Are GxE important in the causation of mental illness?

Yes

- Individuals differ in their vulnerability to pathogens
- There is variably degeneracy of complex biological systems
- There is a paradox between heritable disorders and reproductive disadvantage
- Paradox of low shared environment estimates in twin studies and strong specific environmental risk factors
- These two paradoxes cause attributable risk of environment and genetic factors to sum up to more than 100%.
- There may be a large genetic risk for an illness, but it is imperceptible due to reproductive disadvantage (eg. autism)
- There are KNOWN environmental risk factor for mental illness (eg. cannabis use in adolescents)

3

What are two good reasons for studying GxE?

- Dispeling myth of genetic (or social!) determinism
- Targeted/personalized interventions

4

How does childhood maltreatment effect Monoamine oxidase A and antisocial behaviour?

Maltreatment leads to low MAO-A activity, which is associated with antisocial behaviour and adversity.

5

How is serotonin transporter linked to stress and depression? Childhood maltreatment?

Serotonin transporter is upregulated with more stressful life events. This is also linked to a risk of developing major depression episodes.

Childhood maltreatment also linked with upregulated transporter and risk of major depression. Support attenuates this effect.

6

How can childhood abuse and neglect lead to chronic depression?

Maltreatment leads to
- Reduced quality of intimate relationships
- Stressful life events and difficulties (affecting BDNF)
- Self esteem issues

These converge to cause onset depressive episodes. Perpetuation of onset depression can cause chronic depression. Through GxE childhood abuse and neglect facilitates this perpetuation (through increased 5-HT reuptake etc.)

7

How does the amino acid sequence of BDNF correlate with depression onset?

ValVal: lower rates of depression. Seen with low stressful life events.

ValMet: Higher rates of depression

MetMet: Extremely high rates of depression. Seen with many stressful life events.