Added a paragraph and source entry for Borrus and colleagues' 2026 analysis in the existing limitations guide. It discusses clock reliability, responses in mortality-trained or pace-of-aging clocks, and agreement across clocks. It also notes that an isolated response may reflect clock-specific biology rather than noise. Author consulting relationships are disclosed alongside the source.
Evidence that a clock responds is not the same as evidence that an intervention improves lifespan or healthspan. The addition enriches the existing guide rather than creating a separate article for one paper.
Readers have more context for clock-change headlines. These are proposed confidence checks, not a validated personal decision rule or proof of health benefit. This records an addition released on 12 October; no evidence tier changes with this announcement.