Humans age dramatically at two key points in their life, study finds

By Rosa Rahimi, CNN

(CNN) — Scientists have found that human beings age at a molecular level in two accelerated bursts – first at the age of 44, and then again at 60.

In a study published in the journal Nature Aging, scientists at Stanford University and Nanyang Technological University in Singapore followed 108 participants over several years to observe aging changes in their molecules — RNA, proteins and participants’ microbiomes.

The scientists found that human aging does not happen in a gradual, linear way. Rather, the majority of the molecules they studied showed accelerated, non-linear changes at the ages of 44 and 60.

Xiaotao Shen, an assistant professor in microbiome medicine at Nanyang Technological University and first author of the study, told CNN that the results show “we are not becoming old gradually.” Some points in time are particularly important for our aging and health, he added.

For example, the ability to metabolize caffeine notably decreases – first around the age of 40 and once more around 60. Components involved in metabolizing alcohol also diminish, particularly around the age of 40, Michael Snyder, chair of the department of genetics at Stanford and an author of the study, told CNN, referring to the two waves of aging.

Snyder added that, anecdotally, “people often get muscle injuries and see their fat accumulation hit in their 40s (related to lipid metabolism), and definitely sarcopenia (muscle loss) hit people in their 60s — this is a very big deal.”

Both age groups experienced changes in proteins which hold tissues together, which likely helps explain skin, muscle and cardiovascular changes, he added.

Disease risks also rise faster, particularly after the age of 60. The study found that people age 60 or older are more susceptible to cardiovascular disorders, kidney issues and type 2 diabetes.

Finding patterns like these can help with the diagnosis and prevention of diseases, according to the study, which said it had also identified “clinically actionable markers” that can be used to improve health-care management and the well-being of aging populations.

The study focused on participants between the ages of 25 and 75 for nearly two years, on average. Participants all lived in California, were healthy and came from diverse ethnic backgrounds. Samples of blood, stool, skin and nasal and oral swabs were taken from them every three to six months.

Since accelerated aging in women could have been attributed to menopause (which is typically between ages 45 and 55), the researchers performed analysis on separate male and female datasets. To their surprise, they found the results were similar – suggesting a transition point around 55 could be a common phenomenon for both sexes.

A previous study by researchers in Germany and the United States had found that there is another “wave” of aging around 75, but the latest research was not able to confirm those findings because of the limited age range of the cohort in the trial, Shen told CNN.

As for what to take away from their findings, the researchers advise making lifestyle changes such as drinking less alcohol and exercising more when nearing these pivotal years in your 40s and 60s.

Snyder advised people approaching their 60s to watch their carb intake and drink plenty of water to aid kidney function.

“Take care of yourself more closely at specific time points during your life span,” advised Shen.

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