NAD+
A molecule every cell uses to turn food into energy. Levels tend to fall with age.
Senolytic
A drug or compound meant to clear out old, damaged cells that have stopped dividing.
Senescent cells
Old, damaged cells that have stopped dividing but haven't died.
Biological age
An estimate of how old your body seems, based on body measurements, compared with your age in years.
Epigenetic clock
A test that reads chemical tags on your DNA to estimate a biological age.
Age reversal
The idea of making the body, or parts of it, biologically younger rather than just slowing aging.
Cell reprogramming
Switching on a few genes that make cells act younger, studied mainly in animals.
Preprint
Early results posted before other scientists have checked them.
Randomized trial
A study where people are assigned by chance to get a treatment or not, so the groups can be fairly compared.
Phase 3 trial
A large trial in people, usually the last step before a drug can be approved.
Observational study
A study that watches people over time without giving them a treatment.
Placebo
A dummy treatment, such as a sugar pill, used for comparison in trials.