Caspi et al. (2003)

Question 1

Aim of Caspi et al (2003)

Answer 1

To investigate how polymorphisms of a gene+life events could influence depression (specifically the 5-HTT gene)

Question 2

What was the sample size of Caspi et al (2003)

Answer 2

Opportunistic sample of 847 participants; divided into 3 groups ( G1 :two short alleles, G2 one long and one, short , G3 Two long)

Assessed at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, and 26

Question 3

The procedure of Caspi et al.

Answer 3

Participants were given a questionnaire about stressful life events (employment, financial, housing, health, relationship stressors) after the 21st birthday & before the 26th birthday
Assessed for depressive symptoms at the end (self-report)

Question 4

What were the results of Caspi et al. ?

Answer 4

Found those with two short alleles (instead of one short and one long or two long ) for the serotonin transporter gene were at a higher risk of developing depressive symptoms and/ or depression when exposed to stressful life events

Long alleles seem to protect against depression and demonstrated how genes can predispose people to certain outcomes if environmental triggers are present genes do not necessarily = destiny, environmental plays a key role.

Question 5

What were the strengths of Caspi et al?

Answer 5

Longitutal= validity
Large sample size

Question 6

What were the limitations of Caspi et al?

Answer 6

Self-reporting one questionnaire
Did not account for extraneous genes
Validity/applicability
Ended at age 26 = lack of data
Longitudinal =not ecologically viable