According to a study published in the journal Nature Aging, scientists at Stanford University and Nanyang Technological University in Singapore found that humans age at a molecular level in two accelerated bursts – first at the age of 44, and then again at 60.
The study was conducted on 108 participants over several years to observe aging changes in their molecules — RNA, proteins and participants’ microbiomes.
According this group of scientists, 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.
“we are not becoming old gradually.” Some points in time are particularly important for our aging and health, said, Xiaotao Shen, an assistant professor in microbiome medicine at Nanyang Technological University and first author of the study.
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, according to Michael Snyder, chair of the department of genetics at Stanford and an author of the study.
“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,” said Michael Snyder.
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.
