Social purpose enhances mitophagy flux, leading to better functional aging outcomes without necessarily altering epigenetic age. This hypothesis bridges the gap between mouse longevity interventions that fail to translate to human hard endpoints [1][2] and the observation that epigenetic clock revisions often decouple from survival benefits [4][5]. We propose that perceived meaning activates β‑adrenergic signaling, which raises intracellular cAMP, activates AMPK and PGC‑1α, and thereby stimulates the PINK1/Parkin mitophagy pathway. Improved mitochondrial quality preserves muscle strength, cardiovascular capacity, and cognitive performance—endpoints that matter more than methylation clocks.

To test this, we propose a 12‑month, two‑arm randomized trial in adults aged 60‑80. Arm A receives a structured purpose‑finding program (weekly volunteer coaching, mentorship, and reflective journaling). Arm B receives an active control of health education sessions matched for time and social contact. Primary outcomes are change in hand‑grip strength, VO₂max, and the Short Physical Performance Battery at month 12. Secondary outcomes include plasma markers of mitophagy (cell‑free mitochondrial DNA, LC3‑II/I ratio, p62 levels), inflammatory cytokines, and epigenetic age (GrimAge, PhenoAge) measured at baseline, 6, and 12 months. We will also monitor adherence, adverse events, and concomitant exercise.

If the purpose arm shows a significant increase in mitophagy biomarkers accompanied by improved strength and endurance, while epigenetic age remains unchanged relative to control, the hypothesis is supported. Conversely, if purpose fails to raise mitophagy markers or functional metrics despite high engagement, or if improvements in function are fully mediated by epigenetic age shifts, the hypothesis is falsified. This design directly tests whether a psychosocial driver can uncouple mitochondrial health from the epigenetic clock, addressing the translational mismatch highlighted by failed biomarker‑centric trials and offering a concrete, functional endpoint for future longevity studies.