| Your brain could very well be the gatekeeper of a long life. Having a “youthful” brain and immune system predicts a longer lifespan, researchers at Stanford Medicine found, while having an “aged” brain is linked to earlier death. In fact, it increases mortality risk by more than 180%, they say. But what separates an old brain from a young brain? To calculate the biological age of a person’s brain — and other organs — the scientists took blood samples and isolated about 3,000 proteins that stem from individual organs and change with age. More than 44,000 people took part, with doctors cross-referencing medical records from the UK Biobank with changes in each person’s protein levels over time. Comparing individual results to the average among people in the same age group, they determined whose organs seemed to be aging rapidly and whose were holding onto their youth. The top fifth percentile were dubbed extreme agers. The findings point to the brain and immune system as the main control centers for longevity, lead author Hamilton Oh says. One possible reason is that the brain’s in charge of critical factors involved in aging — like blood pressure, energy levels, stress and the circadian rhythm. The researchers also predicted people’s risk for organ-specific diseases like heart failure, kidney disease and Alzheimer’s disease based on the “age” of those related organs. Having an “old” brain tripled the risk of Alzheimer’s, while aged kidneys and livers were tied to chronic conditions that hinder their function. The study, published in the journal Nature Medicine, should help direct what medical interventions people need for each organ to help lengthen longevity, Oh says, and could lead to new therapies. Until then, there are steps people can take to keep their organs young in hopes of extending their lives, the researchers say. Healthy habits like a nutritious diet and vigorous exercise were givens. In addition, they identified six products — Premarin, ibuprofen, glucosamine supplements, cod liver oil, multivitamins and vitamin C — that were associated with more youthful organs. Unsurprisingly, bad-for-you behaviors like smoking, drinking and a lack of sleep accelerated aging across organ systems. Tony Wyss-Coray, a Stanford professor and the study’s senior author, said he plans to commercialize the process the researchers used. It could be available to the public within two to three years, he says. Even better methods will emerge later as machine learning models improve and home in on a reliable set of proteins, Oh says. Then “they’ll have real clinical utility.” — Michelle Amponsah | 
