Space weather fluctuations and epigenetic aging in an elderly male cohort from Massachusetts, USA

Space weather, comprising galactic cosmic rays (GCRs) and solar and geomagnetic activities (SGAs), was previously associated with shorter telomere length in older men in Massachusetts. In the same cohort, the Normative Aging Study, we analyzed 1487 blood DNA methylation measures from 771 older men during 1999–2013. Daily space-weather indicators included sunspot number (SSN), interplanetary magnetic field, Kp-index, neutron monitor counts, and modeled cosmic ray-induced ionization. The prespecified exposure window was a 30-day moving average. Epigenetic age acceleration across four clocks was the primary outcome; epigenome-wide association (EWAS), regional, and pathway enrichment analyses were secondary and exploratory. In the primary analysis, GCRs were associated with accelerated epigenetic aging, whereas SGAs were associated with slower aging. Each interquartile-range increase in SSN corresponded to 0.61-year lower HorvathAgeAccel and 0.50-year lower PhenoAgeAccel; higher neutron counts corresponded to 0.32-year greater HorvathAgeAccel and 0.29-year greater HannumAgeAccel. In exploratory analyses, EWAS identified hundreds of CpGs associated with GCRs (mostly hypomethylated) and thousands with SGAs (mostly hypermethylated), enriched in P53 signaling, DNA repair, and inflammatory pathways, paralleling astronaut findings. Short-term space weather variation was associated with differences in epigenetic aging measures in this cohort, identifying ground-level space weather as an underexplored environmental correlate of molecular aging.