Biological Age Testing - How to Measure Biological Age

Aging, an inevitable phenomenon like the sunrise, raises many questions for us.
What exactly is this aging? What are its causes? And what does it mean for our health and quality of life?

At its core, aging represents the gradual process of change occurring in living organisms.
This process, which begins in the womb and continues throughout our lives, involves many physiological changes,
including a decline in cellular function, damage to various body systems, and a slowdown in metabolic rate.

But it is important to note that aging is not a uniform and constant process.
There is great variability in the rate and characteristics of aging between different people, even if they are the same chronological age.

The gap between chronological aging - the passage of time measured in years - and biological aging - the physiological changes and decline in cellular function,
highlights the complex nature of the aging process.

While chronological age ticks forward for everyone at a uniform rate,
biological aging is a more accurate narrative, influenced by many factors such as genetics, lifestyle, environment, and even psychological factors.

Understanding the aging process, both at the biological and personal level, is essential for developing strategies to prevent accelerated aging and maintain good health over time.

In this article, we will present a review of innovative testing methods for measuring biological age that allow us to get a more accurate picture of our biological aging.
These tests, including telomere length tests, DNA methylation tests, gene expression tests, and more,
open a window into the mysterious world of the aging process, and allow us to make more informed decisions regarding our health and quality of life.

These are the ways in which biological age can be diagnosed and measured:

1. Telomere Length Test:

This test measures the length of the chromosome ends, called telomeres.
As telomeres shorten with age, the risk of chronic diseases and aging processes increases. However, it is important to know that telomere length is a noisy marker and less stable than advanced epigenetic methods.

What are Telomeres?

Telomeres are the ends of chromosomes, composed of a repeating sequence of DNA and proteins.
They serve as a shield for chromosomes against damage and contribute to maintaining genome stability.
With each cell division, telomeres shorten slightly.
As a result, telomere length serves as a biological measure of chromosome age, and therefore also of a person's biological age.

Advantages of Telomere Length Test:

Simplicity of execution: A simple blood test, no special preparation needed.
Cost: Usually cheaper than advanced epigenetic tests.
Link to aging: Telomere length shortens with age and cell divisions, therefore it serves as a common biological marker for research.

Disadvantages of Telomere Length Test:

High sensitivity to lifestyle and environmental factors: Contrary to what is sometimes claimed, telomere length is greatly influenced by smoking, mental stress, diet, and air pollution, making it a noisy marker and less stable.
High laboratory variability: The common method (qPCR) shows variability between laboratories of over 20 percent, so results from different laboratories are not directly comparable.
Relatively weak mortality prediction: Telomere length is a weaker predictor of mortality compared to epigenetic methylation clocks.
Limited availability: Mainly through direct-to-consumer companies or specialized laboratories. In routine clinical practice, the test is mainly used to diagnose rare disorders in telomere biology, not for general biological age assessment.

What can be learned from a Telomere Length Test?

A telomere length test can provide a lot of information about a person's health status and their risk for chronic diseases and aging processes.

Short telomere length: Associated with an increased risk of diseases such as cardiovascular disease, cancer, diabetes, and neurodegenerative diseases.
Long telomere length: Sometimes linked to better health, but the relationship is complex and not simple. Genetic studies (Mendelian randomization) show that particularly long telomeres are actually associated with an increased risk of certain types of cancer, so longer is not necessarily healthier.

2. DNA Methylation Test:

This test measures DNA methylation patterns, and can provide a wealth of information about biological age, disease risk, aging processes, and even our future health potential.

What is DNA Methylation?

DNA methylation is a chemical process that occurs on the DNA molecule.
This process causes the addition of small methyl groups to specific DNA sites, and accordingly, affects gene expression.
Methylation patterns change with age in a particularly consistent manner, so they can be used as an accurate biological measure of a person's biological age.

Based on methylation patterns, "epigenetic clocks" have been developed, which are currently the most accurate and validated methods for assessing biological age. Among the most prominent are: the Horvath clock (based on 353 CpG sites, 2013), the Hannum clock, and more advanced generation clocks that predict mortality and diseases particularly strongly, such as PhenoAge (Levine), GrimAge, and DunedinPACE.

Advantages of DNA Methylation Test:

Rich information: Can provide information on a wide range of biological processes.
Disease risk identification: Can identify people at increased risk for diseases such as cancer, cardiovascular disease, and neurodegenerative diseases.
Health potential assessment: Can assess a person's future health potential and help them make lifestyle changes for better health.

Disadvantages of DNA Methylation Test:

Higher cost: Usually more expensive than a telomere length test, and performed in specialized laboratories.
Availability: Available mainly through specialized laboratories and dedicated companies.
Note on lifestyle: Methylation patterns can be influenced by lifestyle and environment, and this is actually a strength: they allow seeing how habits affect biological age. It is important to emphasize: despite this influence, methylation clocks are currently the most accurate and validated method, and they predict mortality more strongly than a telomere length test. That is, the influence of lifestyle does not make them less reliable than the telomere test, but rather the opposite.

3. Gene Expression Test:

This test measures the expression of genes related to aging, and can provide a wealth of information about biological age, disease risk, aging processes, and even our future health potential.

What is Gene Expression?

Gene expression is the process by which genetic information is translated into proteins.
This process occurs in every cell in the body and affects its activity and function.
The expression of many genes changes with age, so they can be used as a biological measure of chromosome age, and accordingly, of a person's biological age.

Advantages of Gene Expression Test:

Specific information: Can provide specific information on the expression of genes related to a wide range of diseases and aging processes.
Early risk identification: Can identify people at early risk for these diseases.
Health potential assessment: Can assess a person's future health potential and help them make lifestyle changes for better health.

Disadvantages of Gene Expression Test:

Less available: Less available than other tests, and can only be performed in certain medical laboratories.
More expensive: More expensive than other tests.
Influenced by external factors: Influenced by external factors such as lifestyle and environment, therefore less reliable than other tests.

4. Physical Measures:

A group of relatively simple tests that measure a person's physical ability.
These tests, including a walking test, a cardiorespiratory endurance test, and a muscle strength test, can provide a lot of information about overall health status and physical fitness level.

Advantages of Physical Measures:

Wide availability: These tests are available in a wide variety of places, such as gyms, clinics, and even at home.
Low cost: Compared to other biological age tests, these tests are relatively inexpensive.
Ease of execution: These tests are simple to perform and do not require special knowledge or equipment.

Disadvantages of Physical Measures:

Influence of many factors: Physical measures are influenced by many factors, such as physical training, general health, and diet.
Therefore, it may be difficult to compare results between different people.
Inaccuracy: There may be inaccuracy in the tests, especially if they are not performed correctly.
Limited information: Physical measures provide relatively limited information about aging processes and disease risk.

5. Biological Markers:

A group of blood tests that measure levels of various substances in the blood, such as hormones, inflammation levels, and levels of certain proteins.
These tests can provide a lot of information about overall health status and aging processes.

Advantages of Biological Markers:

Wide availability: These tests are available in a wide variety of clinics and hospitals.
Relatively low cost: Compared to other biological age tests, these tests are relatively inexpensive.
Ease of execution: These tests are simple to perform and only require a blood sample.

Disadvantages of Biological Markers:

Influence of many factors: Biological markers are influenced by many factors, such as diseases, medications, and diet.
Therefore, it may be difficult to compare results between different people.
Inaccuracy: There may be inaccuracy in the tests, especially if they are not performed correctly.
Limited information: Biological markers provide relatively limited information about aging processes and disease risk.