A groundbreaking study published in Nature Aging has introduced a novel epigenetic clock, the Intrinsic Capacity (IC) clock, which predicts age-related decline in physical and mental function more accurately than previous models. Developed by an international team of researchers, this blood-based biomarker not only forecasts mortality but also links lifestyle choices, immune health, and clinical outcomes to the biological aging process.
Understanding Intrinsic Capacity and Its Decline
Intrinsic capacity (IC), a concept introduced by the World Health Organization (WHO) in 2015, represents the composite of an individual’s physical and mental abilities. It peaks in early adulthood and declines with age, influencing susceptibility to disease, disability, and mortality. While IC is a powerful metric for healthy aging, traditional assessments require extensive clinical evaluations, limiting widespread use.
To address this, researchers leveraged DNA methylation (DNAm) data from the INSPIRE-T cohort (1,014 participants aged 20–102) to develop the IC clock. The clock measures five domains of IC:
1. Cognition (assessed via Mini-Mental State Examination)
2. Locomotion (Short Physical Performance Battery)
3.Psychological well-being (Patient Health Questionnaire-9)
4. Sensory function (WHO eye chart and whisper test)
5. Vitality (handgrip strength)
The IC score, ranging from 0 (worst) to 1 (best), showed a strong negative correlation with age (r = −0.65, P = 9.97 × 10-117), with sensory and cognitive domains declining earliest in females and males, respectively.
To address this, researchers leveraged DNA methylation (DNAm) data from the INSPIRE-T cohort (1,014 participants aged 20–102) to develop the IC clock. The clock measures five domains of IC:
1. Cognition (assessed via Mini-Mental State Examination)
2. Locomotion (Short Physical Performance Battery)
3.Psychological well-being (Patient Health Questionnaire-9)
4. Sensory function (WHO eye chart and whisper test)
5. Vitality (handgrip strength)
The IC score, ranging from 0 (worst) to 1 (best), showed a strong negative correlation with age (r = −0.65, P = 9.97 × 10-117), with sensory and cognitive domains declining earliest in females and males, respectively.
The IC Clock: A Methylation-Based Predictor
Using elastic net regression, the team identified 91 cytosine-phosphate-guanine (CpG) sites predictive of IC from blood samples. The model achieved a correlation of 0.61 between predicted and observed IC scores. Notably, these CpGs were largely distinct from those in first-generation (Horvath, Hannum) and second-generation (PhenoAge, GrimAge) epigenetic clocks, suggesting the IC clock captures unique biological aging pathways.
Key findings:
· Sex Differences: Females exhibited earlier sensory decline (age 42 vs. 67 in males), while males showed earlier cognitive decline (72 vs. 86).
· Immune System Link: Higher IC scores correlated with elevated CD28 expression (critical for T-cell function) and fewer exhausted CD8⁺ T cells, markers of immunosenescence.
· Saliva Compatibility: The IC clock performed equally well in saliva samples (r = 0.64), offering a noninvasive alternative.
Key findings:
· Sex Differences: Females exhibited earlier sensory decline (age 42 vs. 67 in males), while males showed earlier cognitive decline (72 vs. 86).
· Immune System Link: Higher IC scores correlated with elevated CD28 expression (critical for T-cell function) and fewer exhausted CD8⁺ T cells, markers of immunosenescence.
· Saliva Compatibility: The IC clock performed equally well in saliva samples (r = 0.64), offering a noninvasive alternative.
Mortality Prediction and Clinical Correlations
When applied to the Framingham Heart Study, the IC clock outperformed existing epigenetic clocks in predicting all-cause mortality (hazard ratio [HR] = 1.38, P = 1.67 × 10⁻²⁹). Individuals with high IC scores lived ~5.5 years longer on average. The clock also predicted risks for cardiovascular disease (HR = 1.29), congestive heart failure (HR = 1.33), and stroke (HR = 1.21).
Clinically, high IC scores associated with:
· Better physical health: Higher bone density, pulmonary function, and grip strength.
· Lower inflammation: Reduced levels of CRP, IL-6, and tau (a neurodegeneration marker).
· Lifestyle factors: Higher intake of omega-3-rich fish (P = 9.32 × 10⁻¹⁰ for docosahexaenoic acid) and adherence to sugar guidelines (P = 3.82 × 10⁻²).
Clinically, high IC scores associated with:
· Better physical health: Higher bone density, pulmonary function, and grip strength.
· Lower inflammation: Reduced levels of CRP, IL-6, and tau (a neurodegeneration marker).
· Lifestyle factors: Higher intake of omega-3-rich fish (P = 9.32 × 10⁻¹⁰ for docosahexaenoic acid) and adherence to sugar guidelines (P = 3.82 × 10⁻²).
Molecular Mechanisms and Domain-Specific Insights
Transcriptomic analysis revealed IC’s ties to immune response and cellular aging:
· Upregulated genes: CD28 (T-cell activation) and mitochondrial electron transport chain genes (vitality domain).
· Downregulated genes: MCOLN2 (promotes viral infection) and CDK14 (linked to inflammation and Parkinson’s).
· Upregulated genes: CD28 (T-cell activation) and mitochondrial electron transport chain genes (vitality domain).
· Downregulated genes: MCOLN2 (promotes viral infection) and CDK14 (linked to inflammation and Parkinson’s).
Limitations and Future Directions
The study had limited representation of very old adults (>90 years) and did not establish causality between immune changes and IC decline. Future research could explore interventions (e.g., omega-3 supplementation) to modulate IC.
Conclusion
The IC clock bridges molecular aging and clinical assessments, offering a robust tool for personalized health monitoring. As lead author David Furman notes, "This biomarker could revolutionize how we track and intervene in aging, shifting focus from disease treatment to preserving functional capacity."
The model is available via a web application, enabling researchers to estimate IC from DNAm data.
The model is available via a web application, enabling researchers to estimate IC from DNAm data.
Source:
Fuentealba M. et al. A blood-based epigenetic clock for intrinsic capacity predicts mortality and is associated with clinical, immunological and lifestyle factors. Nat Aging. 2025 Jun 4. doi: 10.1038/s43587-025-00883-5. Epub ahead of print. PMID: 40467932.
https://www.nature.com/articles/s43587-025-00883-5
Fuentealba M. et al. A blood-based epigenetic clock for intrinsic capacity predicts mortality and is associated with clinical, immunological and lifestyle factors. Nat Aging. 2025 Jun 4. doi: 10.1038/s43587-025-00883-5. Epub ahead of print. PMID: 40467932.
https://www.nature.com/articles/s43587-025-00883-5