Caspi et al (2003)

• What was the main aim of the study regarding the 5-HTT gene?

  To investigate if stressful life events lead to depression in people with a certain variation of the 5-HTT gene
• How many participants were included in the study?

  847 participants
• What study were the participants part of before this research?

  The Dunedin Multidisciplinary Health and Development study
• How were the participants grouped based on their 5-HTT gene variations?

  Into three groups: 17% with 2 short versions, 51% with one long and one short, and 31% with 2 long versions
• What type of study design was used in this research?

  A longitudinal study
• What age range did the participants complete questionnaires about life events?

  Between their 21st and 26th birthdays
• What type of data was collected regarding depression symptoms?

  Quantitative data in a depression score
• What was a significant finding regarding participants with at least one short version of the gene?

  They showed a significant increase in symptoms of depression after stressful life events
• How did the presence of two short versions of the gene affect participants?

  They were more likely to report severe depressive symptoms after multiple stressful life events
• What does the evidence from the study suggest about depression?

  That both nature and nurture work together to increase the likelihood of developing depression
• What are the strengths of the study?

  • Generalisability due to large sample size
  • Practical application for doctors in treating depression
• What are the weaknesses of the study?

  • Some individuals may be naturally prone to stressful life events
  • Short version of 5-HTT might predispose individuals to stressful situations
  • Reliability issues due to self-report data from questionnaires
• Why might the study's use of questionnaires be considered a weakness?

  Because self-report data can lead to exaggerated or minimized symptoms
• If a participant had two long versions of the 5-HTT gene, how might their risk of depression differ from those with short versions?

  They would be less likely to develop depression after stressful life events