Summary:
This prospective cohort study examined whether the thymus, an organ known for shaping the health of the immune system early in life, continues to influence health into adulthood. Although the thymus normally shrinks and becomes fatty with age, the researchers proposed that its remaining function may still matter for long‑term wellbeing. They created a method that measures thymic health from a standard CT scan and applied it to two large prospective cohorts of adults who were followed for more than a decade. Across both cohorts, thymic health differed widely between individuals. When the imaging model was applied to participants in the National Lung Screening Trial and the Framingham Heart Study, people with better‑preserved thymic tissue consistently showed lower risks of major age‑related diseases. Higher thymic health was linked with reduced all‑cause mortality, fewer cardiovascular deaths, and less incidence of lung cancer. These associations were reproduced in another cohort, where stronger thymic health also predicted less risk of cardiovascular health complications. The study also found that thymic health was connected to broader health patterns such as metabolic dysfunction and higher systemic inflammation. Lifestyle factors such as smoking, obesity and low physical activity were associated with lower thymic health, suggesting that modifiable behaviours may influence the rate of thymic decline. This prospective cohort study therefore indicates that the thymus may remain biologically relevant well into adulthood and that variation in thymic preservation could contribute to differences in disease susceptibility and longevity, positioning the thymus as a potential target for preventive or regenerative strategies aimed at healthier ageing.
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Abstract:
The thymus is essential for establishing T cell diversity early in life, but undergoes profound involution with age and has therefore traditionally been regarded as largely nonfunctional in adults1,2. Here we propose that preserving thymic functionality is integral to adult health and longevity. We developed a deep learning framework to quantify thymic health from routine radiographic images and evaluated its association with longevity and risk of major age-associated diseases in two large prospective cohorts of asymptomatic adults: the National Lung Screening Trial (n = 25,031) and the Framingham Heart Study (n = 2,581). In both cohorts, thymic health varied markedly across the population. In the National Lung Screening Trial, higher thymic health was consistently associated with lower all-cause mortality, reduced lung cancer incidence and lower cardiovascular mortality over 12 years of follow-up after adjustment for age, sex, smoking and comorbidities. In the independent Framingham Heart Study cohort, higher thymic health was significantly associated with reduced cardiovascular mortality, independent of age, sex and smoking. Thymic health was further linked to systemic inflammation and metabolic dysregulation, and associated with modifiable lifestyle factors including smoking, obesity and physical activity. Together, these findings reposition the thymus as a central regulator of immune-mediated ageing and disease susceptibility in adulthood, highlighting its potential as a target for preventive and regenerative strategies to promote healthy ageing and longevity.
Article Publication Date: 18/03/2026
DOI: 10.1038/s41586-026-10242-y
