RESUMO
OBJECTIVE: Epigenetics has been described as one of the most exciting areas of contemporary biology, and research has begun to explore whether epigenetic modifications are influenced by psychological processes. The present research explored the associations of health-related motivation and behavior with the DNA methylation of tumor necrosis factor (TNF) gene. METHOD: Participants (N = 88) completed questionnaires examining engagement with health-related behavior (i.e., physical activity, diet, and smoking) and health-related motivation from the perspective of self-determination theory. They also provided a capillary blood sample for DNA extraction and analysis of four CpG sites via bisulfite conversion within Exon 1 of TNF. RESULTS: Health-related autonomous motivation was weakly but positively associated with TNF methylation (ß = .18, p = .08). Indirect effects were identified in a subsequent step; autonomous motivation was positively associated with fruit consumption (ß = .29, p = .004), negatively associated with smoking (ß = -.22, p = .03), but not associated with physical activity (ß = .10, p = .34). Moreover, TNF methylation was positively associated with lifetime physical activity (ß = .18, p = .08) and negatively associated with smoking (ß = -.23, p = .03). Direct effects of autonomous motivation on DNA methylation did not persist when these indirect effects were included (ß = .09, p = .43). CONCLUSIONS: Results support the idea that autonomous motivation is associated with DNA methylation, albeit indirectly through tobacco consumption. (PsycINFO Database Record (c) 2019 APA, all rights reserved).