Everyone ages in their own way
People were divided into groups according to the type of aging
Polina Loseva, N+1
American scientists have found hundreds of substances in human blood, the concentration of which can naturally change with age. They found out that it is difficult to single out unambiguous markers of biological age among them: there will always be people who do not fit into the general rule. But it turned out that all these markers can be divided into four groups: related to immunity, metabolism, kidney or liver dysfunction. As a result, all participants in the study were divided by types of aging: each of them had markers of at least one of the four groups changed with age. The work was published in the journal Nature Medicine (Ahadi et al., Personal aging markers and ageotypes revealed by deep longitudinal profiling).
Each research group offers its candidacy for the role of a marker of biological age. They tried to evaluate it by wrinkles on the skin, and by the amount of individual substances in the blood, and by the intestinal microbiota, and by the degree of DNA twisting in cells. However, none has so far proved to be universal. There are three explanations for this: either it has not been found yet, or the age should be estimated by the sum of several parameters, or there is no universal marker at all, and each person ages in his own way.
To find out whether it is possible to trace the general trend of aging in blood composition, a group of researchers from Stanford University, led by Michael Snyder, worked with a group of 106 healthy people and people with prediabetes aged 29-75 years. For four years, each of them took blood tests, and scientists looked for biomarkers in them that would be associated with a person's personal age changes, the characteristics of a particular age in different people and the differences between a healthy metabolism and prediabetes.
To begin with, scientists were looking for substances whose concentration can predict a person's age. They found 184 such biological markers. But when they began to check how their concentrations change over time for each subject individually, they found that the patterns common to all are not fulfilled by all people. Both for these 184 markers and for other well–known markers of age – for example, creatinine - in some subjects, the changes were strictly opposite to the general trend.
The researchers suggested that the features of the dynamics of markers may be associated with diseases of a particular person. And indeed, when they compared markers that change with age in healthy people and in patients with prediabetes, they found that some changes are characteristic only for some or only for others. At the same time, attempts to find other patterns in the dynamics of markers did not lead to anything: scientists could not find a connection between substances, the amount of which changes over time, and body mass index, medications taken, physical activity and people's diet. The only exceptions were a few cases when the subjects went on a diet or lost weight during the observation, as a result of which their indicators "improved", that is, they began to correspond to a lower biological age.
Based on these results, scientists concluded that the trajectory of aging in humans is determined not so much by external as by internal factors, for example, genetic, or medical history. They suggested that it is possible to divide the subjects into several types of aging. To do this, they collected 608 markers (these included markers that changed with age in at least 6 study participants) and divided them into four groups depending on the physiological processes with which they are associated: immunity, metabolism, impaired kidney and liver function.
It turned out that each study participant showed changes in at least one of these marker groups with age. For someone, for example, it was possible to trace the dynamics only in the group of kidney disorders, and for someone - in all four groups. Thus, scientists have demonstrated, on the one hand, that the aging processes are very heterogeneous, and on the other – that, despite this, they follow fixed trajectories. One can imagine that in the future, by dividing people by types of aging, researchers will be able to better predict the deterioration of their health or select a treatment for old age, which may also be different for each patient.
So far, only one clinical trial is known, during which the biological age of a person was reduced. However, it is not yet clear whether this applies to the patient's entire body or to blood cells. But recently scientists have found out that human aging begins from the very beginning of development, that is, even before birth.
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