TOKYO —

Cells possess an intrinsic housekeeping system, a sophisticated mechanism known as autophagy, dedicated to preventing the detrimental accumulation of damaged materials. This vital process involves the meticulous collection of defective proteins and cellular debris, their encapsulation within specialized vesicles, and their subsequent degradation into fundamental molecular components. These recycled building blocks are then reintegrated into cellular processes, sustaining cellular health and function. For decades, a pervasive understanding in the scientific community has posited that this essential recycling system, autophagy, inevitably wanes with age. This perceived decline has been implicated as a significant contributing factor to a spectrum of age-related diseases, including cancer, cardiovascular ailments, diabetes, and neurodegenerative disorders. However, groundbreaking research emerging from the Sanford Burnham Prebys Medical Discovery Institute is poised to fundamentally alter this long-held paradigm, suggesting that cellular recycling does not uniformly diminish with advancing years. Instead, its activity can exhibit dynamic fluctuations, increasing, decreasing, or remaining stable, contingent upon the specific cell type and the individual’s biological sex. Furthermore, this new study, published on September 27, 2026, in the esteemed journal Aging Cell, hints at a potentially influential role for physical exercise in modulating autophagy activity in older adults, offering a glimmer of hope for innovative interventions promoting healthy aging.

Challenging Long-Held Assumptions About Autophagy and Aging

The prevailing narrative surrounding autophagy and aging has been one of gradual decay. This perspective has been widely accepted, influencing numerous research directions and therapeutic strategies aimed at combating age-related diseases. However, Caroline Kumsta, PhD, assistant professor in the Center for Cardiovascular and Muscular Diseases at Sanford Burnham Prebys and senior author of the study, articulated a critical observation: "We commonly see people cite this idea that autophagy declines with age, but the actual evidence for this in humans is very thin." This statement underscores a significant gap between popular scientific dogma and empirical human data.

Tatiana Moreno, PhD ’26, the lead author of the study and a former graduate student in the Kumsta lab, elaborated on the motivation behind their investigation: "Interest is growing in targeting autophagy to develop new healthy aging interventions. We wanted to challenge assumptions and investigate what actually happens to autophagy during aging in healthy individuals." This research endeavor was thus conceived with the explicit aim of providing a more precise and evidence-based understanding of autophagy’s trajectory throughout the human lifespan.

The Methodology: A Multi-faceted Approach to Cellular Recycling

To unravel the intricate relationship between aging and autophagy, the research team embarked on a comprehensive study, collecting biological samples from a cohort of healthy volunteers spanning a wide age range, from 23 to 72 years old. Crucially, all participants self-reported no pre-existing chronic medical conditions, ensuring a focus on the natural aging process in a generally healthy population. The samples collected included both blood and skin tissue.

A key innovation in their experimental design was the conversion of a subset of the collected skin cells into induced neurons. This sophisticated technique allowed researchers to examine cellular recycling not just in peripheral cells like skin and blood, but also in a cell type more directly relevant to neurological function and aging, thereby providing a more holistic view of autophagy across different cellular contexts.

The analysis of these diverse cell types was multifaceted. Scientists meticulously examined RNA transcripts, which serve as molecular messengers carrying genetic instructions from DNA to guide protein synthesis and other cellular functions. By analyzing these transcripts, the researchers could gauge the activity levels of genes known to be involved in the autophagy pathway. This provided an indirect measure of how age and cell type might influence the cellular machinery responsible for recycling.

However, the team recognized the limitations of relying solely on gene expression data. RNA levels do not always directly correlate with the actual functional output of a cellular process. Therefore, they went a critical step further by directly measuring the rate at which autophagy was actively occurring within the cells. This direct measurement allowed for a more robust assessment of whether the observed patterns in gene expression accurately reflected the true amount of cellular recycling taking place. This dual approach—examining both the genetic blueprint and the functional execution—was crucial for generating reliable conclusions.

Unveiling a Complex Tapestry of Autophagic Activity

The results of this rigorous investigation painted a far more intricate and nuanced picture of cellular recycling and aging than the simplistic narrative of universal decline. "We found that autophagic activity changes were not universal throughout the body and did not follow the idea that autophagy simply declines with age," stated Dr. Kumsta. "Rather, cellular recycling rates are altered differently with age in each of the cell types, and differently by sex in each of the cell types." This statement highlights the study’s pivotal finding: autophagy’s response to aging is not a monolithic phenomenon but a dynamic process that varies significantly based on cellular identity and biological sex.

Age-Specific and Sex-Specific Variations in Cellular Recycling

The study revealed striking divergences in how autophagy responded to aging across different cell types and sexes. In skin cells derived from male participants, a discernible decrease in recycling activity was observed as age progressed. Conversely, in skin cells from female participants, autophagic activity remained relatively stable, showing no significant age-related decline. This sex-specific difference in skin cell autophagy is a novel observation that warrants further investigation into the underlying hormonal and genetic factors.

Perhaps even more surprising was the finding in induced neurons. Neurons derived from female participants exhibited an increase in autophagy with age. This stands in stark contrast to the traditional view of declining cellular function in aging brains and suggests that in certain cell types, particularly in females, the cellular cleanup machinery may become more active to combat age-related cellular insults.

These findings collectively underscore that cellular recycling does not adhere to a singular, predictable pattern across the entire organism. Instead, the aging process appears to selectively influence autophagy, with distinct effects depending on the cellular environment and the individual’s sex.

Gene Expression: A Potentially Misleading Indicator

An important corollary to these findings relates to the reliability of using gene expression levels as a proxy for autophagy activity. The researchers discovered that the expression of genes responsible for autophagy did not consistently predict the actual rate of recycling occurring within the cells. In other words, cells exhibiting higher or lower levels of autophagy gene expression did not necessarily show corresponding increases or decreases in their measured recycling rates.

"This shows that people using static measures such as transcription levels to infer what’s happening with autophagy need to be really careful about their interpretations," cautioned Moreno. This observation has significant implications for the broader scientific community, highlighting the necessity of employing direct functional assays to accurately assess autophagy activity, rather than relying solely on indirect measures of gene expression. This methodological refinement is critical for ensuring the validity and reproducibility of future research in this field.

The Paradoxical Impact of Increased Autophagy in Older Adults

The research team then delved into a critical question: are the observed differences in autophagy associated with tangible differences in physical health and performance as individuals age? Their findings pointed to another unexpected and potentially counterintuitive observation: higher levels of cellular recycling might not always be beneficial, particularly in older adults.

Among participants aged 70 and above, a greater degree of autophagy activity was associated with poorer measures of physical function across all three cell types examined. Specifically, in blood cells, elevated autophagy was linked to reduced aerobic fitness. In skin cells, it correlated with a higher body mass index (BMI). In the induced neurons, increased recycling activity was connected to weaker grip strength, a lower metabolic rate, and a higher resting heart rate.

These associations suggest that while cellular recycling is undeniably crucial for cellular health, its relationship with physical well-being may undergo a transformation later in life. Increased autophagy, which might confer protective benefits in younger individuals by clearing nascent cellular damage, could potentially become detrimental or less efficient in older adults, perhaps due to an overburdened system or a shift in cellular priorities.

"I think this is an important distinction that merits continued study, as it appears that increased autophagy flux may be good in younger people yet problematic in older people," Dr. Kumsta stated. This sentiment emphasizes the need for a nuanced understanding, moving beyond a simple "more is better" or "less is worse" dichotomy.

"Autophagy and aging are so much more nuanced than previously assumed," added Moreno. "To better translate autophagy research discoveries into potential therapies, we really need to understand what is happening on a cell-specific level and how it is affected by sex and age." This highlights the complexity of developing targeted interventions, which must consider these critical variables.

The Promising Role of Gentle Exercise in Modulating Autophagy

In a significant pivot, the researchers explored whether physical activity could serve as a modulator of autophagy in older adults. This inquiry was motivated by the growing body of evidence linking exercise to overall health and well-being in aging populations. In a small but compelling pilot study, five participants, all aged between 77 and 88, engaged in a gentle, 12-week exercise program. The program’s focus was on fall prevention, incorporating activities designed to improve balance, strength, and coordination.

Researchers collected blood samples from these participants both before and after the exercise intervention to measure changes in cellular recycling. The preliminary results were encouraging: the exercise program appeared to lower autophagy activity in blood cells, bringing it closer to levels typically observed in younger adults. Alongside these cellular changes, the participants also demonstrated measurable improvements in their physical performance.

While this pilot study involved a very small sample size, these initial findings offer a tantalizing glimpse into the potential of exercise to positively influence cellular aging processes. The possibility that regular, moderate physical activity could help recalibrate the body’s internal recycling system, thereby promoting healthier aging, is a significant development. Larger, more robust studies will be essential to confirm these preliminary observations, establish the consistency of these changes, and elucidate the precise mechanisms by which exercise exerts its effects on autophagy and overall physical health.

"It is exciting to have this exercise intervention that may have a positive effect on autophagy and healthy aging, and I’m really excited to see where that goes," expressed Dr. Kumsta, underscoring the potential therapeutic promise of this line of inquiry.

The Broader Implications for Healthy Aging Strategies

The findings from the Sanford Burnham Prebys study carry profound implications for how we approach the study of aging and the development of interventions aimed at promoting longevity and well-being. They firmly establish that cellular recycling is not a static process that uniformly deteriorates with age but rather a dynamic and context-dependent phenomenon. This necessitates a paradigm shift in research, moving away from generalized assumptions and towards a more granular understanding of autophagy’s behavior in specific cell types and across different demographic groups.

Future therapeutic strategies targeting autophagy will likely need to be highly personalized, taking into account an individual’s age, sex, and the specific cellular pathways implicated in their health conditions. A one-size-fits-all approach is unlikely to be effective.

Recognizing the potential of exercise as a key intervention, the Kumsta laboratory has secured a pilot grant from the Altman Clinical and Translational Research Institute at the University of California San Diego (UC San Diego). This funding will support further, larger-scale investigations into the exercise-autophagy connection. The team is collaborating with the Exercise and Physical Activity Resource Center at UC San Diego, aiming to recruit a greater number of participants and employ more sophisticated testing methodologies. These expanded studies will seek to comprehensively examine how physical activity influences autophagy, the aging process, and physical function, with the ultimate goal of translating these discoveries into actionable strategies for promoting healthier, more resilient aging.

The research was generously supported by a consortium of esteemed funding bodies, including the National Institutes of Health, the National Cancer Institute, the National Institute on Aging, the American Foundation for Aging Research, the Conrad Prebys Foundation, The Howard and Maryam Newman Family Foundation, and the Leona M. and Harry B. Helmsley Charitable Trust, underscoring the scientific and societal importance of this ongoing research.