Impact of Tissue Sample Type on Biological Age Assessment Revealed by Researchers

A recent study has highlighted the significance of tissue sample type in accurately determining an individual's biological age, a measure that reflects the physiological state of the body rather than the time elapsed since birth. Conducted by researchers from the Penn State Department of Biobehavioral Health, the findings suggest that the accuracy of biological age estimates can vary significantly based on whether oral tissue or blood samples are used.

Biological age differs from chronological age, as it accounts for how well the body is functioning. While chronological age can correlate with disease risk, biological age provides a more nuanced understanding of an individual's health, potentially influenced by various environmental and lifestyle factors. This study, published in the journal Aging Cell, aims to refine the methods of estimating biological age.

Researchers have developed several epigenetic clocks, which are tools designed to compare biological age with chronological age based on DNA methylation patterns. These clocks are created by analyzing tissue samples from numerous individuals and identifying specific epigenetic markers that correlate with age. However, the precision of these clocks is contingent upon the type of tissue used during their creation.

In their investigation, the research team, led by doctoral candidate Abner Apsley, examined five different types of tissue samples alongside seven epigenetic clocks. The study incorporated 284 distinct samples from 83 participants aged between 9 and 70 years. The results indicated that oral tissue samples, such as saliva and cheek swabs, produced significantly less accurate biological age estimates compared to blood samples in six out of the seven clocks tested.

Apsley noted that in many instances, the biological age derived from oral tissue could be overestimated by as much as 30 years, underscoring the necessity for alignment between the type of tissue used for age measurement and that utilized in the development of the epigenetic clock.

The findings also revealed that blood samples yielded consistent biological age estimates across various epigenetic clocks, while oral tissue samples generally indicated older biological ages. A notable exception was observed with one clock that was developed using both blood and cheek swabs, demonstrating improved accuracy across different tissue types.

The implications of this research extend beyond academic interest; they suggest that for companies or healthcare providers aiming to assess biological age using saliva or cheek swab samples, there is a pressing need for the development of specific epigenetic clocks tailored to these tissues. Currently, blood remains the most reliable source for accurate biological age estimations.

While the use of biological age tests is not yet commonplace in clinical practice, the research team believes that these assessments could eventually aid in identifying patients who may require medical interventions to mitigate age-related diseases due to their advanced biological age. Conversely, those with a younger biological age might be better candidates for certain medical procedures.

As researchers continue to explore the applications of biological age assessments, the potential for these estimates to inform clinical decisions in various contexts, including forensic science, remains an exciting frontier.