Everyone is different, and that certainly applies to aging, according to new research that drills down into how people age as individuals rather than looking at population averages.
Everyone ages differently
In a new study, researchers at Stanford University School of Medicine have managed to sort people into different categories based on how they are aging and dubbed these categories “ageotypes” .
There are already various biomarkers of aging that researchers can use to determine how biologically old a person is, but these researchers wanted to take a deeper look at individuals’ aging in order to explore the differing ways that they age. There have been plenty of studies that look at aging at the general population level, but, instead, these researchers have tracked individual people and taken detailed biomarkers for a prolonged period to find out what happens to them as they grow older.
Out of a pool of 106 study participants, the researchers focused on 43 healthy men and women aged between 34 and 68 years of age and tested each of them at least five times a year for two years. The resesearchers used a varied panel of biomarkers to collect highly detailed information about how each of these participants was aging and in what ways.
The researchers used fecal samples, blood, and other biological samples to track the presence and levels of various proteins, metabolites, lipids, and microbes, monitoring their changes over the course of two years.
The researchers discovered that people generally age in four primary ways: metabolic, hepatic (liver), nephritic (kidney), and immune system. For example, people who age faster metabolically are at greater risk for metabolic conditions such as diabetes and are in the metabolic ageotype. People who experience faster immune aging are more likely to experience higher levels of chronic inflammation, are at higher risk of immune-related diseases, and likely have higher incidence of diseases such as cancer; these people are in the immune ageotype.
People can age slower or faster in each of these categories, and all of us are aging in all four. However, the rate is different between individuals, and an ageotype is simply the category in which a person is aging the fastest according to that person’s biomarkers.
The team also looked at the differences in aging between healthy participants and participants who are insulin resistant, a condition that prevents them from properly processing sugar. The researchers found that, in general, there were around 10 biomarkers that varied significantly between insulin-sensitive and insulin-resistant people as they got older. The majority of these biomarkers were linked to inflammation and immune system function.
Ageotype is flexible
Finally and most notably, not every participant in the study experienced an increase in their ageotype; their biomarkers did not change in the two-year period. In some individuals, there was even a brief reversal of those biomarkers as a result of healthier behavior. While these people did ultimately continue to age, the rate at which they did so was reduced. Creatine and hemoglobin A1c, which are indicative biomarkers of kidney function, were both reduced in a small number of the participants.
Most of the people whose A1c was reduced had lost weight due to making dietary changes, and some people with reduced creatine had been taking statins. However, the researchers could not always explain why some biomarkers moved to more youthful levels in a few people who had made no major changes to their lifestyles. Perhaps more intriguingly, there were a small number of people who aged at a significantly slower rate than average during the whole study.
The molecular changes that occur with aging are not well understood. Here, we performed longitudinal and deep multiomics profiling of 106 healthy individuals from 29 to 75 years of age and examined how different types of ‘omic’ measurements, including transcripts, proteins, metabolites, cytokines, microbes and clinical laboratory values, correlate with age. We identified both known and new markers that are associated with age, as well as distinct molecular patterns of aging in insulin-resistant as compared to insulin-sensitive individuals. In a longitudinal setting, we identified personal aging markers whose levels changed over a short time frame of 2–3 years. Further, we defined different types of aging patterns in different individuals, termed ‘ageotypes’, on the basis of the types of molecular pathways that changed over time in a given individual. Ageotypes may provide a molecular assessment of personal aging, reflective of personal lifestyle and medical history, that may ultimately be useful in monitoring and intervening in the aging process.
This study shows that aging is a flexible process and that there is considerable variance in the speed and ways in which people age. People could use their ageotypes as guides to spotlight where and how they are aging the fastest and potentially take steps to change their aging trajectory. Without a doubt, more studies are needed to fully understand ageotypes and why there are such variances between individuals, but this study makes for a solid first step towards ways to optimize health as we age.
 Sara Ahadi, Wenyu Zhou, Sophia Miryam Schüssler-Fiorenza Rose, M. Reza Sailani, Kévin Contrepois, Monika Avina, Melanie Ashland, Anne Brunet & Michael Snyder. Personal aging markers and ageotypes revealed by deep longitudinal profiling. Nature Medicine, 2020 DOI: