Acute stress induces changes in epigenome-wide DNA methylation.

Stress plays a significant role in the development of mental and somatic disorders by dysregulating the hypothalamic-pituitary-adrenal (HPA) axis. Epigenetic mechanisms, particularly DNA methylation (DNAm), are assumed to mediate this relationship, with increasing evidence linking stress experience to DNAm changes, though the longitudinal effects of acute stress remain unclear. Here, 122 healthy individuals underwent the Maastricht Acute Stress Test (MAST). Salivary samples for cortisol measurements were taken at seven time points from before to 45 min after stress induction, and blood was drawn for DNAm analyses before and 45 min after. Cortisol reactivity was predicted by baseline DNAm using robust linear models, and a mixed linear model was performed to investigate DNAm changes over time. Downstream analyses included identifying differentially methylated regions (DMRs) and overrepresented Gene Ontology (GO) Terms. A total of 120 CpG sites and four DMRs were associated with cortisol reactivity, with chromatin modifiers among the top findings. Longitudinal epigenome-wide changes were observed at 32 CpG sites and four DMRs. Overrepresented GO terms were related to learning, cognition, and synaptic processes. Two thyroid-related genes, TTR and TSHR, were observed among the top hits. These findings highlight the association between acute stress and DNAm, suggesting DNAm levels to be related to cortisol reactivity and acute stress to influence DNA methylation patterns dynamically. Key genes involved in thyroid function and transcriptional regulation were implicated in the stress response. Further research with larger samples and multi-omics approaches is needed to confirm these findings, assess their long-term stability, and explore their functional relevance.