Latest Frontier in Longevity: Organ Age

"How old is your pancreas? What about your brain or heart?

Scientists have come up with a way to estimate the age of organs, separate from the body's age as a whole. They found in a recent study that many of us are walking around with at least one organ aging much more quickly than the others, and that older organs can indicate a greater chance of developing diseases.

It is the latest development in the idea that your body's biological age can be different from its chronological one. Knowing the age of organs might one day help prevent and treat disease.

"Heart aging predicts future heart disease, and brain aging predicts future dementia," says Hamilton Oh, one of the paper's lead authors and a graduate student at Stanford.

A simple test to determine organ age is likely still a ways off, but the concept is gaining interest among researchers, doctors and people focused on their own longevity and health. Scientists caution that more research is needed before mainstream use. Some also say that parts of the recent study made too many assumptions.

Most existing biological-age tests, which sell for several hundred dollars, measure chemical changes in DNA. They generally give users a single number estimating their body's biological age or rate of aging.

Attempting to calculate the age of specific body parts goes a step further, and this latest study uses a different technique. Published in the journal Nature in December, it found links between older organs and health problems. An older heart, for instance, was linked to a higher chance of heart failure among generally healthy people. Older arteries and brains were associated with a higher risk of cognitive impairment.

To find this, researchers associated different organs with certain proteins that change with age. They used blood samples to measure the levels of those proteins.

They designed an algorithm to calculate the gap between someone's chronological age and the ages of their organs. Roughly one in five relatively healthy people over the age of 50 has at least one organ aging much faster than the others, according to the study, which included more than 5,500 participants.

The gap, researchers found, could be used to predict how likely a healthy person was to develop certain age-related diseases or die over the next 15 years.

For instance, every roughly four additional years of heart age was associated with a 2.5 times greater risk of heart failure. Healthy people with "older" brains had a 10% greater chance of developing cognitive impairment than those with "younger" brains.

"Understanding more holistically what is happening to someone with aging gives us a more personalized prediction in terms of that person's individual risk," says Morgan Levine, a former assistant professor at Yale who now works at a biotech company. Levine, who wasn't involved with this recent study, has developed biological age blood tests, including one designed to measure organ-specific aging.

The Stanford researchers have co-founded a separate biotech company that has a blood test in development based on the research. They are working on a follow-up study with data from roughly 50,000 people from the UK Biobank, a large health database.

Scientists caution that more research is needed with a wider group of people before an organ-age test would be ready for mainstream use. The links that researchers made between the proteins and organs aren't clearly settled science, says Ben Orsburn, an instructor and principal investigator at the Johns Hopkins University School of Medicine whose research focuses on proteins but who wasn't involved in the study.

Before a test like this reaches patients, scientists say, it should be established what measures -- such as drugs or lifestyle changes -- can help people with high organ-age gap scores reduce their health risks.

"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," says Dr. James Kirkland, a physician and professor of aging research at the Mayo Clinic.

One day patients may be able to tell through a blood test which organs are aging faster and start treatment years before chronic diseases like Alzheimer's, diabetes or hypertension set in, researchers say.

"If that's true, you don't need to start taking biopsies of all different organs," says Austin Argentieri, a researcher on aging at Harvard and Massachusetts General Hospital who wasn't involved with the study." [1]

1. U.S. News: Latest Frontier in Longevity: Organ Age. Janin, Alex.  Wall Street Journal, Eastern edition; New York, N.Y.. 11 Mar 2024: A.3.