31 May 2011

Telomere length analysis – the way to health?

Recently, the Spanish company Life Length has launched a test for sale, which, according to the developers, allows you to determine the biological age of a person by assessing the length of telomeres – the end sections of DNA chromosomes. The appearance of this test caused a violent reaction in the media, and often with headlines like "A test worth 400 pounds will predict the date of your death."

Outstanding researcher Elizabeth Blackburn, who in 2009 shared the Nobel Prize in Physiology or Medicine for her work on the study of telomeres, co-founded the California-based company Telome Health, which developed its own test to determine the length of telomeres in cells from saliva samples.

During the Berzelius Symposium on telomere biology, held last week in Stockholm, Blackburn answered questions from a Nature correspondent about her attitude to press statements and prospects related to the use of telomere length tests in medicine. We give an abridged retelling of her explanations about the possibilities that the study of telomeres opens up.

The claim that the length of telomeres will determine the duration of your life is just nonsense. The test result should be interpreted in context with other information. Telomere length is an indicator of many integrated factors and indicates the overall level of risk for the development of many diseases that often form a complex pathology – for example, diabetes and cardiovascular diseases. This model is still quite new for modern medicine.

We and other research groups observe pronounced statistical correlations between telomere shortening and the risk of developing various diseases that have recently become increasingly common, such as cardiovascular diseases, diabetes and certain types of cancer. 

In one of the studies, we observed aging adults. Those study participants whose telomeres decreased in size over 2.5 years were at 3 times higher risk of dying from cardiovascular diseases over the next 9 years than individuals whose telomeres lengthened or did not change their length.

There are also more and more associations between depression, psychological stress (both chronic and acute – for example, post-traumatic syndrome) and even low levels of education and telomere shortening. Most of this data has not yet been published.

Interventions recommended for poor test results may include, for example, measures to combat stress or exercise, which, according to a growing body of data, contribute to the preservation of telomere length.

Just talking about a healthy lifestyle, the benefits of physical education, etc. sound vague, and the test provides a person with a "printout" of data on the state of his body – even if not absolutely accurate, but estimated with a certain probability. For example, if you exercise, telomere length can become a physiological biomarker of changes in the state of your body for you. Such information may also be useful for doctors. For example, in one of the studies, people with one or more risk factors for diseases of the cardiovascular system were divided into three groups depending on the length of telomeres, after which they were prescribed statins (cholesterol-lowering drugs) or placebo. A few years later, it turned out that statins practically affected patients from the group with the longest telomeres. Interesting correlations between telomerase activity and the human body's response to antidepressants have also been revealed.

Telomere length is not a constant indicator for all cell types. The status of the immune system reflects the diseases developing in the body. For example, heart diseases are associated with the activation of components of the immune system that form inflammation. Inflammation is a universal reaction to wounds and infections, but prolonged inflammatory processes can have a detrimental effect on the body and are associated with chronic diseases, including heart disease. Therefore, for testing, we use leukocytes, which are easy to isolate from a saliva sample.

Neither I nor my colleagues are engaged in the creation of drugs to protect or lengthen telomeres. This idea makes sense, but it should be realized that its implementation will take a lot of time.

Evgeniya Ryabtseva
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of Nature: Spit test offers guide to health


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