How long will you live? Nobel winner claims new test can help

Scientists claim they have developed a blood test that can predict how fast a person is ageing. The test, developed in Spain, is set to be available in the UK soon and to cost €500 (about £435) per test.

When considering a person's age people usually think in terms of their chronological age, and it is not unusual to talk about someone as 'looking good for their age'. The developers of the test claim to be able to tell how well an individual's 'biological age' matches up to their chronological age.

The test measures the length of telomeres - the structures present on the tips of chromosomes that help to protect them from being broken down. Telomeres are slightly shortened each time a cell replicates, which can lead to DNA damage. As a person gets older, the telomeres can become completely eroded, and a number of age-related diseases are due to this.

Professor Elizabeth Blackburn from the University of California, who was awarded a Nobel prize for the initial discovery of the role of telomeres in ageing and disease, told New Scientist: 'Checking your telomere length is a bit like weighing yourself: You get a single number which depends on a lot of factors. Telomere length gives you a sense of your underlying health'.

Professor Blackburn pioneered the development of a test that is currently used in research studies in the USA. However, the test that may soon be available in the UK was developed by Dr Maria Blasco, a researcher at the Spanish National Cancer Research Centre in Madrid, Spain.

Dr Blasco set up the company, Life Length, with the aim of making the test available as an over-the-counter test to the general public. Professor Jerry Shay from the University of Texas, USA, who is also a scientific consultant for Life Length, told the Independent: 'This test devised by [Dr] Blasco is so accurate that it is likely to provide more useful information than some of the other tests out there right now. What makes cells stop growing is the shortest telomeres, not the average telomere length, which is what the other tests look at'.

However, the test has proven to be controversial, even though it is not able to narrow down predictions of life expectancy to months or even years, with some experts questioning its usefulness. Dr Carol Greider from Harvard Medical School, who also received a Nobel Prize for her work on telomeres, told the journal Science: 'Do I think it's useful to have a bunch of companies offering to measure telomere length so people can find out how old they are? No'.

Other commentators have raised concerns about how individuals may react to the results, or even whether such information should be made available to medical and life insurers.