Biological age: How old you can look at 38
Serious differences: According to the study, some 38-year-olds are already 31 years older – biologically speaking
Photo: Patrick Seeger
US study: Over 1000 38-year-olds examined – biological age is up to 33 years apart. 28 to 61 years.
Durham. U.S. researchers studied more than 1,000 38-year-olds – and came to clear conclusions. Biological age differs greatly even at a relatively young age. 38 years old – the age that shows up on your ID card. The biological truth is different: Here, the age ranges from 28 to 61. Using various markers such as kidney and lung function, U.S. researchers determined biological age and came up with results ranging from under 30 to over 60 years of age.
Until now, ageing research has focused mainly on older people. "But if we want to prevent age-related diseases, we need to study aging at a young age," lead author Dan Belsky of Duke University said in a statement released about the study.
The basis for the study, the results of which were presented in the "Proceedings" of the U.S. National Academy of Sciences ("PNAS"), is the so-called "Dunedin Study": As part of this ongoing long-term survey, 1037 people from the New Zealand city of Dunedin were followed from birth to 38 years of age. Regular health and psychological examinations were carried out until the age of 38.
We age at different rates
The researchers developed a method to measure and compare the extent and speed of aging in young adults: According to Belsky, the process of aging shows up earlier in human organs than in eyes, joints and hair. Consequently, the international team of researchers tested 18 corresponding biomarkers, which included kidney and lung function, as well as liver and immune system values. In addition, cholesterol, heart fitness and the length of the telomeres, the chromosome ends that shorten with age, were measured. The study also recorded dental health and the condition of the small blood vessels behind the eye, which are considered indicators of the condition of blood vessels in the brain.
Using such values, the scientists calculated the biological age of the 38-year-old subjects: It ranged from 28 to 61 years. The researchers then compared the data with the study participants’ test results when they were 26 and 32 years old to determine individual age processes. The result: most participants actually aged one biological year each year. Some, however, aged three years every chronological year, while others did not age at all and remained younger than their biological age. Those whose biological age was higher than 38 aged correspondingly faster. They also showed greater IQ decline, signs of increased risk of stroke and dementia, and decreased motor skills. The traces of aging were already detectable at the age of 26, according to gerontologist Belsky.
Subjects who were biologically older also performed worse in balance and coordination exercises and in cognitive tests. In addition, they themselves more often reported having physiological problems, for example, when climbing stairs. The medically collected data was additionally supported by the subjects’ external perceptions: Duke University students, for example, used photos of the 38-year-olds to estimate their age. Those who were biologically older were also classified as older.
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Intervening in the aging process
Overall, the researchers hope their analysis grid will help intervene in the aging process as a whole, rather than treating individual age-related diseases in isolation. Valuable for this are findings from twin research, which suggest that aging is only 20 percent genetically determined. The rest is due to environmental influences. It is precisely those environmental influences that would leave room for a medical influence on the aging process, the researchers write. "As we get older, our risk for various diseases increases," Belsky says. "To prevent multiple diseases at the same time and not play blind man’s buff, aging itself must be our goal."
The findings of Belsky and his colleagues are particularly relevant against the background of an aging world population. In this context, the World Health Organization (WHO) has already warned of the challenges for healthcare systems. In 2020, the proportion of those aged 60 and older will exceed the number of under-fives for the first time, WHO says. By 2050, they said, two billion older people can be expected, compared with 841 million today. For Germany, the German Federal Statistical Office predicts that the proportion of people over 65 will be almost one-third of the total population in 2050. (dpa)