THE NEW YORK TIMES – If you’ve ever been to a high school reunion, you know that some people seem to age faster than others. Twenty-five years after graduation, one classmate can appear a decade younger than the rest, another a decade older.
“People know that intuitively,” said Dr. Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine, “but they don’t understand that it’s a biology that we’re trying to discover.”
Scientists are working to quantify this phenomenon and put a number to a person’s “biological age” by looking at their cellular health instead of how many years they’ve been alive. Some of these measurements are now marketed as direct-to-consumer blood tests.
But before you shell out hundreds of dollars to find out how old you really are, make sure you know what you’re paying for. Experts caution that while these tests are interesting in theory, and could be valuable research tools, they aren’t ready for prime-time.
How do you measure biological age?
Researchers define biological age as “the accumulation of damage we can measure in our body,” said Dr. Andrea Britta Maier, co-director of the Centre for Healthy Longevity at the National University of Singapore. That damage comes from natural aging, as well as from our environment and behaviors.
The concept is often attributed to the British physician-scientist Dr. Alex Comfort (perhaps better known for writing “The Joy of Sex”), who published a 1969 paper on the idea. But for decades, scientists didn’t know how they might measure someone’s biological age.
A major advance came in 2013 when Steve Horvath, a professor of human genetics and biostatistics at the University of California, Los Angeles, proposed using a “clock” based on the emerging field of epigenetics.
Over the course of our lives, our DNA accumulates molecular changes that turn on and off various genes …
