AbstractSocioeconomic position (SEP) is a major determinant of health across the life course. Yet, little is known about the biological mechanisms explaining this relationship. One possible explanation is through an epigenetic process called DNA methylation (DNAm), wherein the socioeconomic environment causes no alteration in the DNA sequence but modifies gene activity, gene expression, and therefore long-term health. To understand the evidence supporting a potential SEP-DNAm link, we performed a systematic review of published empirical findings on the association between SEP (from prenatal development to adulthood) and DNAm measured across the life course, with an eye toward evaluating how the timing, duration, and type of SEP exposure influenced DNAm. Across the 37 studies we identified, there was some evidence for the effect of SEP timing and duration on DNAm, with early-life SEP and persistently low SEP being particularly strong indicators of DNAm. Different indicators of SEP also had some unique associations with DNAm profiles, suggesting that SEP is not a singular concept, but rather that different aspects of the socioeconomic environment can shift DNAm patterns through distinct pathways. These differences with respect to SEP timing, duration, and type were notable because they were detected even among heterogenous study designs. Overall, findings from this review underscore the importance of analyzing SEP timing, duration, and type, given the complex relationship between SEP and DNAm across the lifespan. To guide future research, we highlight current limitations in the literature and propose recommendations for overcoming some of these challenges.
Epidemiological Study Designs: Traditional and Novel Approaches to Advance Life Course Health Development Research