Researchers running a randomized trial in older adults with depression assigned one group to a course of cognitive behavioral therapy and compared their blood-based epigenetic clocks against a control group over the treatment period, according to the study reported this week in the journal covered by Medical Xpress. The therapy group showed a slower rate of biological aging by that marker than controls. The mechanism is not mystical: chronic depression keeps cortisol elevated and inflammatory signaling switched on, and both accelerate the DNA methylation changes that epigenetic clocks are built to detect. Reduce the psychological load that is driving the stress response, and the clock that reads out that stress response moves slower too.

What the trial establishes is narrow and still real: a specific psychological intervention, delivered by trained therapists over a defined course, changed a validated biomarker of aging in people who were clinically depressed to start with. What it does not establish is that therapy, or stress reduction generally, extends lifespan in people who were not depressed, or that the epigenetic clock used here predicts who gets sick and when, a question these clocks still answer imperfectly across populations. The honest read is that the nervous system and the aging clock are more connected than the anti-aging supplement aisle usually credits, and that the connection ran through actual mental illness, not the ordinary stress of a bad week.