# Randomized controlled trial (RCT)

A randomized controlled trial (RCT) is an experiment in which participants are assigned to an intervention or a control group by chance. It is the most reliable way to tell whether a treatment actually causes the effect you see. Randomizing spreads both known and unknown confounders evenly across the groups. So any difference in outcome can be put down to the intervention, not to pre-existing differences between groups. Blinding (hiding who got what from participants, clinicians, or assessors) reduces bias. Double-blind designs, where neither side knows the assignment, are the strongest setup. In longevity research, RCTs separate causal claims from mere association. Several things that looked protective in cohort studies showed smaller or no benefits when tested rigorously. RCTs in aging science are hard, because meaningful endpoints, like delayed multimorbidity or a longer lifespan, can take decades to measure. The TAME trial (Targeting Aging with Metformin) shows the effort to test a geroscience idea at scale. It plans to enroll about 3,000 adults aged 65 to 79, with a composite age-related-disease endpoint. As of 2026, no anti-aging treatment has finished a powered RCT with all-cause death as its primary endpoint in humans.

## Sources

- Schulz KF, Altman DG, Moher D, et al.. (2010). CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials. BMJ. https://doi.org/10.1136/bmj.c332
- Newman JC, Milman S, Hashmi SK, Austad SN, Kirkland JL, Halter JB, Barzilai N. (2016). Strategies and Challenges in Clinical Trials Targeting Human Aging. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. https://doi.org/10.1093/gerona/glw149

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_Canonical: https://longevity-switzerland.com/en/glossary/randomized-controlled-trial · Part of Longevity Cities · Updated 2026-06-22_