Scientists Discover 4 Distinct Patterns of Aging

From Live Science.com (Jan. 16, 2020):

Some people's hearts stay strong well into their 60s, but their kidneys begin to fail. Others may have the kidneys of a 30-year-old but fall victim to constant infection.

Now, scientists may be one step closer to understanding why the aging process varies so drastically between people.

Even within a single person, aging unfolds at different rates in different tissues, sometimes striking the liver before the heart or kidney, for example. People fall into distinct categories depending on which of their biological systems ages fastest, and someday, doctors could use this information to recommend specific lifestyle changes and design personalized medical treatments, according to a new study, published Jan. 13 in the journal Nature Medicine.

What's your "ageotype"?

The research team behind the study sorted 43 people into aging categories, or "ageotypes," based on biological samples collected over the course of two years. The samples included blood, inflammatory substances, microbes, genetic material, proteins and by-products of metabolic processes. By tracking how the samples changed over time, the team identified about 600 so-called markers of aging — values that predict the functional capacity of a tissue and essentially estimate its "biological age."

So far, the team has identified four distinct ageotypes: Immune, kidney, liver and metabolic. Some people fit squarely in one category, but others may meet the criteria for all four, depending on how their biological systems hold up with age. 

"Now, it's going to be a lot more than just four categories," said senior author Michael Snyder, a professor and the chair of genetics at the Stanford University School of Medicine in California. For instance, one participant in the study appeared to be a cardiovascular ager, meaning their cardiac muscle accumulates wear-and-tear at a greater rate than other parts of their body. "If we [surveyed] 1,000 people, I'm sure we'll find other cardio agers and that category will become better defined." And with more research, even more patterns of aging may emerge, Snyder added.

In the past, scientists have hunted for markers of aging in enormous datasets for large populations, Snyder, told Live Science. Researchers pinpointed markers of aging by comparing data from young people to that of older people, but for individuals, that kind of data captures only a specific moment in time. It cannot reveal how a given person might change as they age, Snyder said.    

In a clinical setting, that means population-based markers might not be the best measure to determine how a patient is aging, or what combination of medical treatments might suit them best, he added.

"Population-based decisions are crude at best," Synder said. They won't necessarily hold up for you, per se."

By tracking specific people through time, Snyder and his co-authors hoped to learn how aging markers differ between individuals. Their study participants ranged in age from 29 to 75 and provided at least five biological samples over the course of two years. Even within that relatively short time frame, several patterns of aging emerged.

For example, immunological agers accumulated more markers of inflammation through time, while metabolic agers accrued more sugar in their blood, indicating that their bodies were metabolizing glucose less efficiently. Similar to scores on a personality test, each individual's aging "profile" included a combination of traits, mixed and matched from different ageotypes. [read more]