20 November 2017

Conflicting tests

Regardless of whether it is a free online test, a genetic analysis for $ 300 or a blood test for $ 800, any tool claimed to allow determining the correspondence of a person's aging rate to his chronological age is of great interest to a large number of people. However, unfortunately, the only way to get the right answer to such an exciting question is to wait and see everything with your own eyes.

A direct comparison of the results of 11 methods for assessing the rate of human aging, including those offered on the commercial market of chromosome and blood tests, showed that they contradict each other.

These results were obtained by scientists when analyzing data collected in a study involving almost 1,000 residents of Dunedin, New Zealand, whose condition was actively monitored from the day of birth until the age of 38.

Researchers who previously worked with this cohort published a panel of 18 biological parameters that allows predicting the rate of aging of a particular person based on the nature of changes in these markers from 26 to 38 years.

However, when they expanded the boundaries of their analysis to make sure that at the age of 38, these and other parameters point in the same direction, the picture became much less clear.

According to the head of the study, associate Professor Daniel Belsky from Duke University, people age at different rates and specialists in geriatric medicine should have tools to measure it. However, when assessing various aspects of human physiology, ranging from genes and blood markers to a sense of balance and grip strength, the authors saw solid discrepancies. At the same time, he emphasizes that today it is still very premature to offer tests to assess the individual rate of aging in a wide market.

As part of their work, the authors analyzed many physical parameters of aging, including a sense of balance, grip strength, coordination of movements, physical limitations, cognitive function and its extinction, their own subjective assessment of the state of health, as well as the degree of aging of the face according to the estimates of others.

Measuring the length of telomeres – the end sections of chromosomes shortening with age – did not allow reliably predicting physical and cognitive changes. The only possible exception is facial aging. (Currently, an aging test based on telomere length is available to everyone for $300.)

The researchers also analyzed hundreds of regions of the genome in search of changes in DNA methylation profiles – molecular labels that provide activation and inactivation of genes. These epigenetic profiles have previously been studied by other scientists and are regarded as a kind of "biological clock" of the rate of aging. The authors analyzed the state of three such epigenetic "clocks" at the age of 26 and 38 and revealed the expected 12 years of "aging".

Belsky notes that, despite the sufficient chronological accuracy of all three analyzed epigenetic clocks, they poorly reflect the physiological changes occurring in the human body, as well as possible violations of physical and cognitive function. This calls into question the expediency of their use to predict the duration of a healthy life of patients or populations of people.

In addition, the authors applied algorithms developed by other groups to analyze large data arrays containing values of physiological parameters, such as blood test results and parameters of heart and lung functions, and obtained somewhat clearer results.

In order to find out whether the biological parameters of aging allow predicting physical or mental changes, the researchers conducted a statistical comparison of the results of all the tests performed among themselves. As a result, they found that physiological parameters give slightly better results than telomere length and epigenetic clock. However, none of the analyzed parameters turned out to be accurate enough to be able to talk about the expediency of its inclusion in the annual medical examination.

However, the researchers are not giving up and plan to continue searching for the optimal marker of aging. Belsky notes that currently experts are actively searching for methods to slow down aging. Therefore, in the near future they will need a method for evaluating the results of anti-aging therapy. Ideally, this method should be inexpensive and non-invasive, so that it can be used before and after the clinical trial to evaluate the results of the intervention, and the underlying marker should be linked to the chronological age of the person.

Article by Daniel Belsky et al. Eleven Telomere, Epigenetic Clock, and Biomarker-Composite Quantifications of Biological Aging: Do They Measure the Same Thing? published in the American Journal of Epidemiology.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Duke University: Aging Tests Yield Varying Results.

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