Caspi et al (2003)

Aim and Hypothesis

To determine if there is evidence for a gene-environmental interaction for a mutation of the serotonin transporter gene 5HTT (reuptake of serotonin), those with shorter alleles will show symptoms of depression

Procedures

847 New Zealand 26 year olds, all were members assessed for mental health issues every other year until 21 years old. 3 different groups, group 1 has 2 short alleles, group 2 had one short and one long, group 3 has two long alleles. The mutation of the 5-HTT gene has shorter alleles, 43% of people. The participants filled a questionnaire about the frequency of stressful events between 21-26. Depression was also checked

Results

People who has one or more short alleles had more depression and suicidal symptoms in response to stress. It was necessary to inherit the gene and stress to increase likelihood of depression. In a later study, those with the 2 short 5-HTT genes became depressed after 3 or more life events and those with 2 longer alleles were unaffected.

Conclusion

Correlational study so no cause and effect, self-reported events , there must be an interaction between biological and environmental factors in depression(holistic), observations only