The Forgotten Organ That Could Predict How Long You Live
Researchers used AI to analyze CT scans from tens of thousands of adults and found that people with healthier thymuses lived longer and had substantially lower risks of heart disease, cancer, and death.
Researchers at Mass General Brigham have uncovered compelling evidence that the thymus, a small immune system organ long thought to lose its importance after childhood, may play a major role in adult health and longevity. Two groundbreaking studies published in Nature found that adults with healthier thymuses were significantly more likely to live longer and less likely to develop serious diseases, challenging decades of medical assumptions about this overlooked organ.
Located in the chest, the thymus helps train T cells, a crucial type of immune cell that defends the body against infections and disease. Because the organ gradually shrinks after puberty and produces fewer new T cells over time, most scientists had assumed it played only a limited role in adult health. This led to the thymus receiving relatively little attention in large population health studies, despite earlier research linking T cell diversity to aging and immune function decline.
Using artificial intelligence to evaluate routine CT scans, researchers analyzed data from more than 25,000 adults in a national lung cancer screening trial and over 2,500 people in the long-running Framingham Heart Study. They measured the size, structure, and composition of participants' thymuses and created a "thymic health" score based on these measurements. The results revealed dramatic differences in health outcomes based on thymus condition.
People with higher thymic health scores experienced remarkably better outcomes across multiple health measures. Compared with individuals who had poorer thymic health, they showed approximately 50% lower risk of death from any cause, 63% lower risk of death from cardiovascular disease, and 36% lower risk of developing lung cancer. These relationships remained statistically significant even after researchers accounted for age and other health factors.
Dr. Hugo Aerts, director of the Artificial Intelligence in Medicine Program at Mass General Brigham and corresponding author on both papers, emphasized the potential implications. "The thymus has been overlooked for decades and may be a missing piece in explaining why people age differently, and why cancer treatments fail in some patients," he said. The research suggests that declining thymic health may reduce T cell diversity, making it harder for the immune system to recognize and respond to new threats such as cancer and infectious diseases.
