July 07--If scientists want someday to make the old young again, they increasingly recognize they'll need to study young people who seem old. But when a group of researchers recently set out to define what it means to be prematurely old, they discovered that humans age at remarkably different rates, and that we start aging earlier than one might guess.
And for those who feel like they're growing old before their time, the researchers found even worse news: Young adults already showing signs of aging aren't just prematurely old; they seem to be getting older faster than the rest of us.
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FOR THE RECORD
This post has been corrected to reflect that the Dunedin study was conducted in New Zealand, and that 954 subjects participated.
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Led by Duke University's Daniel W. Belsky and Terrie E. Moffitt, the latest research effort explored what aging looks like in the third and fourth decades of life. In a group of 954 study participants all born in Dunedin, New Zealand, in 1972 and '73, researchers had a single, well-studied cohort to test out measures of aging.
As members of the cohort reached 26, and again at ages 32 and 38, the researchers measured their metabolic and immune function and the state of their gums, hearts, lungs, blood vessels, kidneys and livers. They recorded such readily measurable things as BMI and waist-to-hip ratio. And they measured the length of certain telomeres -- the shoestring-like ends of DNA fragments that fray with age.
They toted these up, and even in the absence of classical "diseases of aging," researchers could detect heavy signs of aging in some, and age's light touch upon others.
By the tender age of 38, they found, the 952 people tracked since birth ranged in "biological age" from 28 to 61 years old.
Compared with their slower-aging peers, study members who were aging fast showed greater IQ declines from childhood and signs of increased stroke and dementia risk. Their balance was poorer, their fine-motor control was weaker, and, as judged by such measures as grip strength, they were not as strong.
They knew it -- and it was clear to others as well. Fast-aging individuals were more likely to report poorer health. And independent observers judged them to look older than they did slow-aging individuals.
In all, the researchers found that 18 biomarkers -- physiological measures -- are likely more than enough to judge a person's biological age and to ascertain well in advance of any age-related diseases' onset that he or she is racing to life's finish line.
That's important not just for the individual involved -- with lifestyle changes, some measures of aging can be reversed. The Duke researchers' inventory of aging is also important to researchers interested in delaying and preventing age-related diseases and extending life.
Recognizing accelerated aging early may also cast light on some of the earliest influences on aging: genes, prenatal circumstances, childhood experiences and socioeconomic influences.
Finally, aging may be normal. But just like any disease, efforts to prevent, delay or reverse it are probably best started well before it is clearly evident. If anti-aging advances are to be made, researchers will not only need hordes of older clinical trial participants to test them; they will need efficient ways to recognize trial subjects in an early "at-risk" state, when the effects of intervention have longer to work -- and when they may be more likely to work.
The new research was published Monday in the journal PNAS.
