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):

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.


Are GxE important in the causation of mental illness?


- 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)


What are two good reasons for studying GxE?

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


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.


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.


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.)


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.