Genes (Caspi)

Question 1

Introduction (Genes are made of DNA, they are responsible for…)

Answer 1

Genes are made of DNA, they are responsible for the synthesis of particular proteins that may result in a specific trait or behavior

Question 2

What is a genotype?

Answer 2

Set of traits that are biologically coded into DNA

Question 3

What is a phenotype?

Answer 3

Set of traits that are manifested in the body, appearance, or behavior (both observable and unobservable)

Question 4

What is genetic heritability?

Answer 4

The extent to which differences in the appearance of trait or behavior can be accounted for differences in genes

Question 5

What are epigenetics?

Answer 5

How behaviors and the environment can cause changes that affect the way genes work (nurture influences nature eg. behavior, cognition, personality). Different genes can be turned on or off.

Question 6

Caspi aim

Answer 6

Explored the effect of the 5HTT (serotonin transporter gene), a type of protein that transports serotonin to regulate it, the “heritability” (or difference) in 5HTT alleles is hypothesized to be CONNECTED to depression (synaptic gaps end up with too much, or too little serotonin)

Investigates how gene mutation and epigenetics can play a role in MDD → stress theories of depression predict that an individual’s reaction to stressful events is based upon their genetic predisposition (how many neurotransmitters released in reponse to stressful situations)

Question 7

Caspi procedure

Answer 7

• 847 NZ adults who were assessed for mental health every single year
• Divided into 3 groups based on their 5-HTT alleles (Group 1: 2 short, Group 2: 1 short, 1 long, Group 3: 2 long) 5-HTT gene has shorter alleles
• Fill in “Stressful life events” questionnaire about stressors and assessed for depression

Question 8

Caspi findings

Answer 8

• Version w short allele exhibited depressive and suicidal behavior
• Strongest effect for those who experienced stressful life events

Question 9

Caspi link

Answer 9

Just having the gene mutation is not enough → may increase your susceptibility to depression but it’s the stressful life events (environmental stressors) that increase likelihood of developing depression (genetic predisposition is also a factor towards this)