CELL FREE DNA RESPONSES AS A MARKER OF ACUTE PSYCHOSOCIAL STRESS

The present study aimed at characterizing the response of cell free mitochondrial DNA (cfmt-DNA) to a psychosocial stress test in children and at comparing it with established stress markers, including cortisol (Hypothalamic-Pituitary-Adrenal [HPA] axis), alpha amylase (Sympathetic Nervous System [SNS]), and subjective stress response.
A total of 184 children aged 7-8 years from the ABCD community cohort in Sabadell participated in the Trier Social Stress Test (TSST). Five saliva samples were collected during the procedure. DNA was extracted and levels of NADH dehydrogenase subunit 1 (ND1) as a marker of cfmt-DNA and for beta-2-microglobulin (B2m) as a marker of nuclear DNA (nDNA) were determined with a multiplex quantitative PCR procedure. Salivary cortisol was analyzed by radioimmunoassay and alpha amylase by enzymatic activity. Subjective stress was assessed using the Self-Assessment Manikin (SAM).
Both cfmt-DNA and nDNA showed substantial intra-individual variability. Cfmt-DNA and nDNA were strongly correlated (r=0.861, p<0.001). The TSST elicited significant changes in both cfmt-DNA and nDNA. cfmt-DNA levels declined at the end of the TSST and subsequently returned to basal levels (Time effect X² = 28.4 p<0.001). Nuclear DNA showed a similar pattern (Time effect X² = 41.4 p<0.001). No sex differences were found. Nuclear DNA levels across the TSST were modestly associated with alpha amylase (r=-0.155, p=0.045) and SAM scores (r=0.166, p=0.034).
This study is the first to characterize the cfmt-DNA response to psychosocial stress in children and suggests that detection of mitochondrial DNA in saliva could be a relevant biomarker of acute stress.