A single blood test can unveil the biological ages of 11 distinct organs and systems in the body, potentially indicating disease risks in those areas.

“Our objective is to enhance care using one test that reflects not just the overall biological age, but identifies which system is primarily influencing it,” explains Raghav Sehgal from Yale University. “This way, individuals can receive tailored lifestyle or treatment recommendations based on their profiles.”

To evaluate an individual’s lifespan and health risks, biological age serves as an indicator of the rate at which their body ages, contrasting this with chronological age, according to Morgan Levine at Altos Labs in California. Researchers have designed an epigenetic watch to assess DNA methylation, which involves the addition or removal of chemical tags that toggle genes on and off.

While it’s convenient, its accuracy is questioned by Levine. Different organs and systems age at varied rates, heavily influenced by genetics and medical history, she highlights.

“There is a common belief that within an individual, organs and systems can be distinct.” Vadim Gladyshev from Harvard University, who did not partake in the research, notes. “Some brains may exhibit older characteristics, while kidneys may age differently compared to other organs.”

Thus, Sehgal, Levine, and their colleagues embarked on creating methylation tests that target aging states in various body parts. Initially, they assessed physical measurements, including blood tests, medical histories, and grip strength from around 7,500 individuals involved in two major research programs, namely the Health and Retirement Study—a database of U.S. residents over 50 and some U.S. families contributing DNA for genomic research.

Researchers searched for clear connections between age-related conditions, encompassing immune, inflammatory, hematological, musculoskeletal, hormonal, and metabolic systems along with five key organs linked to the heart, lungs, kidneys, liver, and brain. They then correlated these findings with DNA methylation patterns, trained computer models to recognize those patterns, calculated the biological age of each system, and generated an overall biological age.

After training their models, the team tested it on blood samples from another 8,125 individuals whose data originated from four other studies. They discovered, for instance, that the model’s heart score could predict heart disease, brain scores were associated with cognitive decline, and musculoskeletal scores indicated whether individuals were likely to have arthritis-like conditions.

Comparing their findings with established epigenetic clocks, the researchers noted that organ-specific scores demonstrated strong accuracy, with many yielding excellent results. “It’s quite remarkable that a single factor measured through a blood test can effectively estimate aging across multiple systems,” remarks Levine.

Daniel Belsky from Columbia University in New York describes the epigenetic clock as representing “significant” advancements in aging research. “This marks the initial foray into developing interpretable measures of biological aging that allow for simultaneous analysis of multiple systems, guiding back to specific tissues or organs,” he explains. “It provides a pathway for reverse-engineering from aggregate measurements to pinpoint where health issues may emerge.”

Nonetheless, he cautions that this method might deviate from the overarching objectives of the field. “The essence of genetic science and the potential of aging biology resides in perceiving humans as coherent systems where we seek to identify the weakest links to bolster and avert failures,” Belsky asserts. “Maintaining this integrated perspective is crucial.”

Crucially, Levine clarifies that this test is not intended for diagnostic purposes but for risk assessment. “All assessments, including those in our studies, aim to provide estimates and insights into the inner workings of our bodies,” she emphasizes. “Future research should yield stronger and more precise estimates of aging by integrating various approaches, capturing the complexity and diversity of the aging process.”

Gladyshev envisions that this research could lead to personalized disease prevention strategies. “This represents the core implication of this series of studies,” Belsky adds, while emphasizing the need for further investigation. “We’re not quite there yet.”