Influence of Life Stress on Depression: Moderation by a Polymorphism in the 5-HTT Gene (summary and comments)
Influence of Life Stress on Depression (summary and comments on scientific study)
This study addresses the possibility that individuals with specific genetic variations may be more susceptible to depression when faced with significant environmental stressors. This is known as a Gene-x-Environment (G x E) interaction. The study included measures to verify that its findings were not results of pure genetics - for example, one’s genes causing them to “invite” stressful events into their life, rather than outside events (environment) being independent catalysts for depression. The researchers followed a cohort of about a thousand people from birth until age twenty-six. Stressful life events from age 21-26 were measured through the “life history calendar,” and past-year levels of depression were measured through the use of the “diagnostic interview schedule.”
Based on the findings of this study, individuals with “s” alleles are more likely to develop mild to severe depression than those with homozygous “l/l” alleles when faced with multiple difficult life events. Indeed, genetic predisposition coupled with environmental interaction predicted a higher risk of morbidity among participants. Individuals displayed symptoms of depression at rates that were in line with the researcher’s predictions. Implications of these findings include approaches to pharmacological intervention, risk factor assessment, and preventative measures for predisposed individuals.
Strengths of this journal include the large sample size and controlling for outside factors. Furthermore, the use of quality assessment tools for instances of stress and depression through obtaining input from family members and/or friends enhanced the accuracy of the measurements. Conversely, lots of nuance and detail can fall through in large-scale quantitative research. It also seems like this study has not been replicated, leaving the potential for different results following replication.
The study focuses on a specific age and I wonder what results might emerge when applying these tests in groups at later stages in life, when they may be more experienced with coping mechanisms and being resilient. I would include more qualitative material in the results by including more specifics about which life events resulted in differing levels of depression.
Original study:
https://www.science.org/doi/10.1126/science.1083968