Is Mental Age More Important Than Actual Age? Even Among Peers, the Internal Clock Differs — Research Shaking Up the Concept of "Biological Age"

Is Mental Age More Important Than Actual Age? Even Among Peers, the Internal Clock Differs — Research Shaking Up the Concept of "Biological Age"

Do two people with the same birthday age at the same rate?

On the calendar, yes. However, when tracking changes in the blood over the years, a different picture emerges. A study published by a British research team in the journal 'Science' found significant individual differences in gene activity and metabolite changes, even among healthy people of the same age group.

"People can stay young at heart." You might think of such words. However, what was examined this time was not how old the person feels, but how the molecules in the blood change over time . Understanding this difference reveals the true intrigue of the research.


"Average aging" does not necessarily mean your aging

The study subjects were 335 women aged 32 to 80 participating in the UK twin study "TwinsUK." The research team analyzed blood repeatedly taken from the same individuals over a period of up to eight years. They examined which genes were active in the blood and how metabolites reflecting bodily activities changed.

During the observation period, temporal changes were seen in the activity of 5,061 genes and 181 types of metabolites. However, this does not mean "all of these changed solely due to aging." The focus of the research is on how the changes appear differently when averaged across the entire group versus when tracking each individual.

For example, even if there is a trend of "increasing over time" for a certain molecule across the group, not everyone experiences an increase. Some people have smaller changes than others, or even a decrease. While average values are essential for understanding a group, they alone cannot predict the course of an individual in front of you.

This discovery urges caution against the view that "at age X, this change should be happening in the body." Age is important information. Nonetheless, it is difficult to determine a single molecular state from the same age.


The immune system does not decline uniformly

In addition to individual differences, the way changes occur varies by bodily system, which is also a point of interest.

In the study, changes suggesting functional decline were observed in cells involved in "acquired immunity," which remembers and responds to specific pathogens. Meanwhile, in parts of "innate immunity," which reacts quickly to invaders, there was a tendency for activity to be maintained or increased. Researchers suggest that this combination may be related to chronic inflammation associated with aging.

However, the movement of molecules in the blood alone cannot determine a person's immune strength or future diseases. The findings obtained this time provide clues that aging is not a simple phenomenon progressing in the same direction throughout the body.


The "time" and "season" of blood sampling also matter

Adding to the complexity is that measurement values are influenced by factors other than age. The research team reported that not only genetic differences but also daily rhythms, seasons, and exposure to environmental pollutants are related to molecular changes.

This becomes an important perspective when considering tests that claim biological age. Even if "body age" is indicated as a single number from blood on a given day, that value can be influenced by the conditions at the time of measurement and what indicators were chosen. This study did not evaluate individual commercial testing services. Nonetheless, caution is needed in treating a single measurement value as the overall picture of a person's aging .

From a single photograph, you cannot understand the plot of an entire movie. The study emphasized repeatedly measuring the same person to observe "that person's own changes."


Reactions seen on social media: Interest in the research and questions about measurements

The reactions confirmed on social media were centered more on introductions from researchers and related fields rather than large-scale discussions by general users.

One of the co-researchers explained on LinkedIn that aging at the molecular level is dynamic, situation-dependent, and highly individual. Another researcher's post received comments questioning the analysis of proteins not covered in this study. Interest is directed not only at the discovery that "there are individual differences in aging" but also at "what should be measured for a sufficient understanding."

On the other hand, it cannot be said from the confirmed posts that reactions such as "this study found a way to rejuvenate" or "keeping a youthful mindset can prevent molecular aging" are spreading. It is important to separate the study's content from the impression given by attractive headlines.


In Japan, reconsidering the use of age as a number

In Japan, there are many opportunities to consider health check results and changes in physical strength in relation to age. "Whether it is better or worse than the average of the same age group" is an easy-to-understand measure. This study does not propose abandoning that measure. In addition to comparisons with the average, it shows the value of looking at how one has changed from their previous self .

In the future, if we can more reliably read molecular changes for each individual, it may help distinguish between changes associated with normal aging and early signs of disease. However, the participants in this study were 335 women, mainly examining blood. It remains to be confirmed whether it can be similarly applied to men, different groups, or organs other than blood, and how much the measurement results will actually improve clinical practice.

Age increases at the same rate for everyone. Nevertheless, inside the body, each person has a different course. What this study showed is not the answer that "how old you feel determines aging." Even within the single number of the same age, there are diverse changes .


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