A simple blood test can predict life expectancy

Small RNA molecules in the blood, known as piRNAs, may be a more reliable indicator of short-term survival than age, cholesterol, or lifestyle. This is shown by new research led by Duke Health in collaboration with the University of Minnesota.

The study indicates that a simple blood test could help identify which older adults are at a higher risk of death within the next two years. The research, led by Duke Health in collaboration with the University of Minnesota, suggests that these small RNA molecules in the bloodstream could offer a new way to assess short-term risk in individuals aged 71 and older.

Researchers analyzed blood samples from over 1,200 older participants, focusing on small RNA fragments called PIWI-interacting RNAs (piRNAs). These molecules are involved in regulating development, regeneration, and immune function. It was found that lower levels of certain piRNAs are associated with longer survival.

“The combination of just a few piRNAs proved to be the strongest predictor of two-year survival in older adults—stronger than age, lifestyle habits, or any other health indicator we examined,” says Prof. Virginia Byers Kraus, senior author of the study and a professor in the departments of medicine, pathology, and orthopaedic surgery at Duke University School of Medicine. According to her, the most surprising aspect is that this strong signal comes from a simple blood test.

Using artificial intelligence and machine learning, the team analyzed 187 different health indicators alongside 828 small RNA molecules. The advanced models showed that just six piRNAs could predict two-year survival with 86% accuracy. The results were also confirmed in a second independent group of older participants.

In terms of short-term survival, piRNAs proved to be a more reliable indicator than age, cholesterol levels, physical activity, and over 180 other clinical measurements.

Participants who lived longer consistently showed lower levels of certain piRNAs. A similar correlation has been observed in laboratory organisms—for example, in C. elegans (small roundworms), reducing overall piRNA levels is associated with a doubling of lifespan.

“We know very little about piRNAs in the blood, but what we are seeing is that lower levels of some of them are associated with better outcomes,” says Kraus. “When these molecules are present in higher quantities, it may be a signal that something in the body is not functioning optimally. Understanding the causes could open new possibilities for therapies aimed at healthy aging.”

The team plans to investigate whether treatments, lifestyle changes, or medications—including new classes of drugs such as GLP-1 agonists—can influence piRNA levels. A comparison between their levels in the blood and in various tissues is also planned to better clarify their function.

“These small RNAs act as a kind of micromanagers in the body, controlling numerous processes related to health and aging,” Kraus summarizes. “We are only beginning to understand how significant they are. The research shows that we can assess short-term risk through a practical and minimally invasive blood test—with the ultimate goal of improving health in old age.”