The next breakthrough for longevity obsessives: measuring organ age

• A study measured the age of specific organs in 5,676 adults and found that 20% had advanced aging in one.
• The study found that those with accelerated heart aging have a 250% higher risk of heart failure. 
• The study builds on the idea of "biological age," a measure of your age based on biochemistry. 

A growing body of evidence suggests age is more than just a number. 

Take multimillionaire Bryan Johnson. On paper, he's 46 years old. But he's been making headlines by contesting the idea that it means something about his health — and lifespan. Through a rigorous antiaging regimen that involves eating a strict vegan diet, exercising regularly, and taking more than 100 pills a day, Johnson's doctors told Bloomberg his test results show that he's achieved the heart of a 37-year-old, the skin of a 28-year-old, and the lung capacity of an 18-year-old. 

So, how old is he, exactly? Johnson's doctors told Bloomberg that he's reduced his "biological age" by about five years. Biological age has become a buzzword in longevity circles and is "the true age that our cells, tissues, and organ systems appear to be, based on biochemistry," according to the National Institute on Aging. But the idea that a singular number can represent it is controversial partly because there's no standard for normal aging, as BI previously reported. Even Johnson's test results prove that organs don't all age at the same rate. 

The latest breakthrough in longevity research suggests there may be a way to measure the age of specific organs. A recent study in Nature utilized machine learning models to analyze the age of 11 major organs for 5,676 adults. One of the study's key findings was that about 20% of people had accelerated aging in one organ, associated with a 20 to 50% higher mortality risk. 

Knowing your "oldest organ" might also tell you more about your health trajectory — and the age-related diseases you could develop — than your biological age. The study found that individuals with accelerated heart aging, for example, have a 250% higher risk of heart failure. Every additional four years of age increased an individual's risk of developing heart disease by almost 2.5-fold over 15 years, the study noted. It also found that accelerated brain and vascular aging in an individual can predict the progression of Alzheimer's disease as strongly as the best biomarker test for the disease.

The technology to measure age organ-by-organ is far from ready to mainstream. Still, the concept has attracted the interest of those in longevity circles, according to The Wall Street Journal. Some researchers told the Journal that there may be a day when patients can test the age of their organs through a simple blood test. It's not a far-off idea, given that there are already blood tests that can test for cancer.

However, some scientists believe there's little merit in providing patients with these details before we devise interventions for them.

"It's not going to be terribly helpful for someone to know they might arguably get a particular age-related disease early unless there are preventive steps or other interventions they can take to help that," Dr. James Kirkland, a physician and professor whose research focuses on aging at the Mayo Clinic, told the Journal.