Accelerated DNA methylation age in adolescent girls: associations with elevated diurnal cortisol and reduced hippocampal volume.
Level 3 - non-randomized controlled study
Longitudinal observational cohort study measuring biological and neuroimaging markers over time.
PubMed 28850111 · doi:10.1038/tp.2017.188
What was done
In a longitudinal study of 46 adolescent girls, researchers evaluated the associations among diurnal cortisol output, DNA methylation (DNAm) age, and hippocampal volume. Diurnal cortisol was measured as area under the curve across two daily collection periods. DNAm age was determined using established CpG site algorithms, and accelerated epigenetic age was calculated as the residual score after adjusting for chronological age. Hippocampal volumes were segmented automatically from T1-weighted structural MRI scans.
What was found
The abstract reports directional relationships without numerical statistics (such as effect sizes or p-values). Higher diurnal cortisol production was associated with accelerated DNA methylation age, which was in turn associated with reduced left hippocampal volume. Accelerated DNA methylation age significantly mediated the association between diurnal cortisol and left hippocampal volume.
Why it matters
This study provides preliminary evidence that accelerated epigenetic aging may serve as a biological link between hypothalamic-pituitary-adrenal axis dysregulation and neural structural alterations during adolescence.
Limits
The sample size is very small (n = 46) and restricted solely to adolescent girls, limiting generalizability to males and other age groups. The abstract reports no numerical effect sizes or confidence intervals. As an observational study, it cannot establish causality among cortisol, epigenetic age, and brain structure.
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