Narrative review of biological aging clocks as biomarkers of human aging
This narrative review describes biological aging clocks that combine molecular, clinical and multi-omics biomarkers to estimate aging-related phenotypes beyond chronological age, and it stresses limits in specificity, causal interpretation and clinical applicability. [1]
Automatic summary · not editorially reviewed
The key findings
Biological age is proposed as a complementary construct to chronological age for quantifying differences between individuals in aging trajectories. [1]
Biological aging clocks are classified into three generations by training objective: predicting chronological age, estimating morbidity and mortality risk, and quantifying pace of aging from longitudinal biomarker changes. [1]
The review states that current evidence suggests biological aging clocks are distinct operationalizations of biological aging rather than interchangeable measures of a single construct. [1]
The source at a glance
- Study type / format
- Narrative review (abstract only)
- Population / context
- Human aging as discussed in a narrative review of biological aging clocks
- Summary based on
- Study abstract
- Original publication
- August 31, 2026
Clocks as complementary to chronological age
The review presents biological age as a proposed complementary construct to chronological age, meant to capture differences between individuals in aging trajectories. Biological aging clocks integrate molecular, clinical and multi-omics biomarkers to estimate aging-related phenotypes beyond chronological age. The authors frame clock development within the hallmarks and domains of aging, highlighting age-related methylome remodeling, immunosenescence and chronic low-grade inflammation.
Supporting source [1]
Three clock generations by training objective
The review classifies biological aging clocks into three generations according to their training objectives. First-generation clocks were optimized to predict chronological age; second-generation clocks were designed to estimate morbidity and mortality risk; third-generation clocks were developed to quantify the pace of aging from longitudinal biomarker changes. Multi-omics and artificial intelligence-based approaches are also reviewed as attempts to capture the multidimensional nature of aging.
Supporting source [1]
Distinct measures, not interchangeable constructs
The authors note remaining limitations regarding biological specificity, causal interpretation, reverse causation, confounding, generalizability and clinical applicability. They conclude that current evidence suggests biological aging clocks represent distinct operationalizations of biological aging rather than interchangeable measures of a single construct. Future progress, they write, will require longitudinal, mechanistic and diverse population-based studies to improve interpretability, reproducibility and translational utility.
Supporting source [1]
How to interpret this
This is a narrative review; only the abstract was reviewed, not the full text. The abstract reports no study design details, sample, follow-up or numerical results, and it names limitations of clocks including biological specificity, causal interpretation, reverse causation, confounding, generalizability and clinical applicability.
Based on the study abstract; the full paper, tables and supplementary data were not reviewed.
Source & supporting passages
Fermín-Martínez CA, García-González SB, Castañeda EGL, Ramírez-Rivera DL, Carrillo-Herrera KB, Cabrera-Quintana LA, López-Teros MT, Antonio-Villa NE, Gomes-Goncalves N, García-Peña C, Bello-Chavolla OY. · europepmc.org · August 31, 2026