Review of biological and genetic clocks used to measure aging and death risk in people

Thirty-three biological clocks were evaluated for their predictive performance in measuring aging.

• Biological clocks may be categorized into phenotypic and epigenetic types.
• Phenotypic clocks use easily measurable clinical biomarkers to gauge age.
• Epigenetic clocks utilize cellular methylation data and have shown high accuracy in predicting chronological age.
• Phenotypic clocks have been associated with better mortality predictions than chronological age alone.
• The review systematically surveys proposed clocks while excluding mitotic clocks and models based on non-human samples.
• Insights into the most influential clinical measurements used in phenotypic clocks were also reported.

Simplified