Science defines at what age a person is “old”

In Brazil, a person can be considered elderly from the age of 60 — a bill is being processed to raise the minimum age to 65 years. However, would it be possible to find out at what age a person starts to become “old”, with the body showing the first signs of decline? According to researchers at Stanford University, this process begins, on average, at age 34. The peak of old age comes after the age of 78.

To find out when a person begins the aging process, chronological age was not taken into account, that is, that measured in years lived. The calculation was made based on the different levels of proteins present in the plasma (the part of the blood without cells) of more than 4 thousand individuals, aged between 18 and 95 years.

When do we start to age?

“Aging is a predominant risk factor for several chronic diseases that limit life expectancy”, say the researchers, in an article published in the scientific journal Nature Medicine.

With the acceleration of the biological clock, some signs of old age become very visible, such as wrinkles on the face, gray hair, reduced hearing and vision levels, sluggishness and, sometimes, urinary incontinence.

However, researchers argue that this external process begins much earlier, inside the organism. The first changes begin at age 34 and continue until age 60, in the phase defined as adulthood. From 60 to 78 years old, the individual experiences late maturity. After the age of 78, old age finally arrives — here, the person is “old”.

As chronological age advances, the levels of 373 proteins decrease significantly in plasma until they are no longer produced. The culprit is the loss of DNA repair capacity.

How was age calculated?

“We have known for a long time that measuring certain proteins in the blood can provide information about a person’s health status,” says Tony Wyss-Coray, professor of neurology and one of the study’s authors, in a note. The issue is that this used to be done individually, without considering hundreds of proteins simultaneously.

To construct the new definition of old age, the researchers measured the levels of 3,000 proteins in 4,200 people of varying ages. From the most common ones, they identified that changes in 373 of them are related to old age.

“When the relative levels [das proteínas] undergo substantial changes, this means that you have also changed”, points out researcher Wyss-Coray. Therefore, this is a very safe formula for tracking the stages of a person’s life.

Using AI

Based on these results and other research, the same group of Stanford scientists managed to develop an artificial intelligence (AI) algorithm capable of evaluating the biological age of each organ in an individual and estimating the risk of that “part” stopping working. In the future, this will allow for early corrections, before diseases emerge, improving the quality of life for the oldest-old.

Source: Nature Medicine and Stanford University

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