BAKU – The candles on your birthday cake don’t tell the whole story. As anyone who ever attended a high-school reunion can tell you, some people age faster than others, according to NEWS Medical.
Whoever put the candles on your cake probably didn’t have to guess your chronological age. But research has shown that we also have what’s called a “biological age,” a cryptic but more accurate measure of our physiological condition and likelihood of developing aging-associated disorders from heart trouble to Alzheimer’s disease.
We all guess people’s actual ages, almost unconsciously, by scanning their faces for wrinkles, baggy eyes, and other telltale signs. But figuring out how old someone’s brain, arteries, or kidneys are is another matter. The organs tucked inside our bodies are aging at different speeds, too, according to a new study by Stanford Medicine investigators.
They can even predict who is most likely to die from medical conditions associated with one or more of the 11 separate organ systems the researchers looked at: brain, muscle, heart, lung, arteries, liver, kidneys, pancreas, immune system, intestine, and fat.
The biological age of one organ – the brain – plays an outsized role in determining how long you have left to live, Wyss-Coray said.
“The brain is the gatekeeper of longevity,” he said. “If you’ve got an old brain, you have an increased likelihood of mortality. If you’ve got a young brain, you’re probably going to live longer.”
Wyss-Coray, the DH Chen Professor II, is the senior author of the study, set to be published online in Nature Medicine on July 9. The lead author is Hamilton Oh, PhD, a former graduate student in Wyss-Coray’s group.
The scientists zeroed in on 44,498 randomly selected participants, ages 40 to 70, who were drawn from a longitudinal data-gathering endeavor called UK Biobank. This ongoing effort has collected multiple blood samples and updated medical reports from some 600,000 individuals over several years. These participants were monitored for up to 17 years for changes in their health status.
Wyss-Coray’s team made use of an advanced commercially available laboratory technology that counted the amounts of nearly 3,000 proteins in each participant’s blood. Some 15 percent of these proteins can be traced to single-organ origins, and many of the others to multiple-organ generation.
The researchers fed everybody’s blood-borne protein levels into a computer and determined the average levels of each of those organ-specific proteins in the blood of those people’s bodies, adjusted for age. From this, the scientists generated an algorithm that found how much the composite protein “signature” for each organ being assessed differed from the overall average for people of that age.
Based on the differences between individuals’ and age-adjusted average organ-assigned protein levels, the algorithm assigned a biological age to each of the 11 distinct organs or organ systems assessed for each subject. And it measured how far each organ’s multiprotein signature in any given individual deviated in either direction from the average for people of the same chronological age. These protein signatures served as proxies for individual organs’ relative biological condition. A greater than 1.5 standard deviation from the average put a person’s organ in the “extremely aged” or “extremely youthful” category.
One-third of the individuals in the study had at least one organ with a 1.5-or-greater standard deviation from the average, with the investigators designating any such organ as “extremely aged” or “extremely youthful.” One in four participants had multiple extremely aged or youthful organs.
For the brain, “extremely aged” translated to being among the 6 percent to 7 percent of study participants’ brains whose protein signatures fell at one end of the biological-age distribution. “Extremely youthful” brains fell into the 6 percent to 7 percent at the opposite end.
The algorithm also predicted people’s future health, organ by organ, based on their current organs’ biological age. Wyss-Coray and his colleagues checked for associations between extremely aged organs and any of 15 different disorders, including Alzheimer’s and Parkinson’s diseases, chronic liver or kidney disease, Type 2 diabetes, two different heart conditions and two different lung diseases, rheumatoid arthritis and osteoarthritis, and more.
Risks for several of those diseases were affected by numerous different organs’ biological age. But the strongest associations were between an individual’s biologically aged organ and the chance that this individual would develop a disease associated with that organ. For example, having an extremely aged heart predicted higher risk of atrial fibrillation or heart failure, having aged lungs predicted heightened chronic obstructive pulmonary disease (COPD) risk, and having an old brain predicted higher risk for Alzheimer’s disease. (AZERTAC)