At the molecular level, aging appears to be much more individual than previously thought. Healthy people of the same age can experience very different biological aging pathways.
This is reported by a research team led by Julia El-Sayed Moustafa from King’s College London in the journal “Science”. “Understanding such individual differences over time will be crucial for future approaches to precision medicine,” the scientists are convinced.
Molecular aging refers to the sum of all biochemical and cellular changes that occur in our cells and tissues over time and ultimately lead to the loss of function of organs and the typical appearance of aging.
For the analysis, 335 women from the British twin cohort “TwinsUK” were repeatedly examined over a period of up to eight years. The participants were between 32 and 80 years old.
The team recorded gene activity in the blood and 1,197 metabolites in the blood serum. Over a median period of six years, more than 5,000 genes and 181 metabolites changed, including many that are associated with age-related diseases such as cardiovascular and neurodegenerative diseases.
For individual participants, the changes were sometimes significantly different or even opposite to the general trends. One of the genes whose activity decreased over time was the tumor suppressor gene TP53 - which probably changed the risk of cancer.
Some molecular features showed particularly strong differences between individual participants. These included CXCL9, a gene that is associated with cardiac aging. The authors see this as evidence that biological aging cannot be determined solely by calendar age.
According to the information, the courses were not only influenced by genetic factors. The time of day and season also played a role, and a significant proportion of the genes and metabolites were related to this.
Additionally, environmental contaminants such as PFAS – long-lasting industrial chemicals known as forever chemicals – left molecular traces. Serum levels of certain PFAS decreased over the course of the study, according to the authors, following restrictions on use in the United Kingdom.
There were differences between different areas of the immune system. While evidence of a decline in function was found in cells of the adaptive immune system, the activity of parts of the innate immune system was reportedly maintained or increased.
The researchers explain that this could contribute to chronic inflammatory processes in old age. The innate immune defense reacts quickly and non-specifically as the first line of protection against intruders, while the adaptive immune defense takes targeted action against specific pathogens and forms an immunological memory.
“Rather than there being a single molecular roadmap for aging, our study shows that people progress through different biological trajectories,” said El-Sayed Moustafa. “Two healthy people of the same age can age surprisingly differently at the molecular level.”
The researchers see the results as a basis for being able to better distinguish healthy aging processes from early pathological changes in the future. In the long term, they believe, knowledge of individual molecular aging processes could be useful for more precise prevention and personalized medicine.
