TOKYO —

Cells possess an intricate internal maintenance system, a natural cleanup crew known as autophagy, crucial for preventing the accumulation of damaged materials. This vital process meticulously gathers defective proteins and other cellular debris, encapsulating them within specialized compartments for subsequent breakdown into fundamental molecular building blocks that can be efficiently repurposed. For decades, scientists have widely accepted the notion that the efficiency of autophagy diminishes with age, linking its decline to a spectrum of age-related diseases, including cancer, cardiovascular ailments, diabetes, and neurodegenerative disorders. However, groundbreaking research published on September 27, 2026, in the prestigious journal Aging Cell by scientists at the Sanford Burnham Prebys Medical Discovery Institute is poised to fundamentally alter this understanding. The study’s findings suggest that cellular recycling activity does not uniformly decelerate with advancing years; instead, its pace can fluctuate, increasing, decreasing, or remaining stable, contingent upon the specific cell type and the individual’s sex. Furthermore, this pioneering research hints at a potentially significant role for exercise in modulating this fundamental cellular process, particularly in older adults.

Challenging the Dogma of Declining Autophagy

The prevailing scientific consensus has long posited autophagy as a key indicator of cellular aging, with its perceived decline being a "hallmark of aging." This perspective has fueled substantial research into targeting autophagy for therapeutic interventions aimed at combating age-related diseases. However, Dr. Caroline Kumsta, PhD, the senior and corresponding author of the study and an assistant professor at Sanford Burnham Prebys, voiced 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 assertion underscores a critical gap between popular scientific narrative and empirical human data, prompting the researchers to embark on a mission to rigorously investigate the reality of autophagy’s behavior throughout the human lifespan.

Tatiana Moreno, PhD ’26, the lead author of the study and a former graduate student in the Kumsta lab, elaborated on the study’s impetus: "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 desire to move beyond assumptions and establish a more accurate, data-driven understanding of autophagy’s role in aging has led to a significant recalibration of established scientific thought.

A Comprehensive Investigation into Cellular Recycling and Aging

To dismantle the long-standing assumptions surrounding autophagy and aging, the research team implemented a multi-faceted approach, collecting biological samples from a diverse cohort of healthy volunteers. Blood and skin samples were meticulously gathered from participants spanning the ages of 23 to 72, all of whom reported no pre-existing chronic medical conditions. This careful selection ensured that the observed changes could be more directly attributed to the aging process itself, rather than being confounded by underlying health issues.

A critical innovation in the study’s methodology involved the conversion of a subset of collected skin cells into induced neurons. This strategic step enabled the researchers to simultaneously examine cellular recycling dynamics across three distinct cell types: blood cells, skin cells, and neurons. This comparative approach was essential for discerning whether autophagy operated uniformly across different tissues or exhibited cell-type-specific responses to aging.

The analysis delved deep into the molecular machinery governing autophagy. For each cell type, the scientists meticulously examined RNA transcripts. These transcripts serve as molecular messengers, transcribed from DNA, carrying genetic instructions for the synthesis of proteins, enzymes, and other vital cellular components. By analyzing the abundance and patterns of autophagy-related gene transcripts, the researchers aimed to ascertain how age and cell type influenced the expression of genes involved in the autophagic pathway.

Crucially, the study did not solely rely on indirect measures of gene expression. To provide a more direct and robust assessment of autophagic activity, the researchers also directly measured the rate at which cells performed autophagy. This direct quantification allowed them to validate whether the observed patterns in gene expression accurately reflected the actual amount of cellular recycling taking place. This dual approach, combining genetic analysis with functional measurements, provided a more comprehensive and reliable picture of autophagy’s operational status.

Surprising Nuances in Age-Related Autophagy

The results of this comprehensive investigation painted a far more intricate and surprising picture of cellular aging than the traditional, simplified narrative. Dr. Kumsta summarized the core findings: "We found that autophagic activity changes were not universal throughout the body and did not follow the idea that autophagy simply declines with age. 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 marks a significant departure from the long-held belief in a monolithic decline of autophagy.

The study revealed striking sex- and cell-type-specific variations in how autophagy responded to aging. In skin cells derived from male participants, a clear trend of decreasing recycling activity was observed as age advanced. In contrast, female skin cells exhibited a relatively stable autophagic rate throughout the study period. Even more remarkably, induced neurons derived from female participants demonstrated an increase in autophagy with age. These findings unequivocally demonstrate that cellular recycling does not adhere to a singular, predictable pattern across the human body. Instead, the aging process appears to exert differential influences on autophagy, modulated by both the specific cellular environment and the individual’s biological sex.

Furthermore, the research highlighted a critical caveat regarding the interpretation of gene expression data. The study found that the expression levels of autophagy-related genes did not reliably predict the actual rate of recycling. Cells exhibiting higher or lower levels of gene expression did not necessarily demonstrate corresponding differences in their measured autophagic flux. "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 carries significant implications for future research, emphasizing the need for direct functional measurements to accurately assess autophagic activity.

The Complex Relationship Between Increased Autophagy and Health

Beyond understanding the basic patterns of autophagy in aging, the researchers delved into the functional implications of these changes, investigating whether variations in autophagy were associated with physical health and performance in older adults. Their findings introduced another unexpected layer of complexity, suggesting that heightened cellular recycling might have divergent implications for younger and older individuals.

Among participants aged 70 and older, a compelling association emerged: greater autophagic activity was linked to poorer measures of physical function across all three cell types examined. In blood cells, elevated autophagy correlated with diminished aerobic fitness. For skin cells, increased recycling was associated with a higher body mass index (BMI). In the induced neurons, heightened autophagic flux was connected to a suite of indicators of reduced physical capacity, including weaker grip strength, lower metabolic rate, and a higher resting heart rate.

These correlations challenge the simplistic assumption that increased autophagy is inherently indicative of healthier aging. While autophagy undoubtedly plays a critical protective role in cellular homeostasis, its relationship with physical health appears to shift and potentially become detrimental later in life. "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," stated Dr. Kumsta. This observation suggests that the optimal level of autophagy may vary significantly across the lifespan, with what is beneficial in youth potentially becoming detrimental in senescence.

Moreno echoed this sentiment, emphasizing the nuanced nature of the autophagy-aging connection: "Autophagy and aging are so much more nuanced than previously assumed. 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 call for a granular, cell-specific understanding is crucial for the development of targeted and effective interventions.

The Promising Role of Gentle Exercise in Modulating Autophagy

In a potentially transformative finding, the researchers explored whether physical activity could influence autophagy in older adults. In a small, yet illuminating pilot study, five participants, all between the ages of 77 and 88, engaged in a 12-week gentle exercise program. The program was specifically designed to reduce the risk of falls, focusing on functional mobility and balance. Blood samples were collected from these participants both before and after the intervention to meticulously measure any resultant changes in cellular recycling activity.

The preliminary results of this pilot study offered a beacon of hope. They suggested that engaging in gentle exercise could potentially lead to a reduction in autophagy activity in blood cells, bringing these levels closer to those typically observed in younger adults. Furthermore, participants in the exercise group demonstrated notable improvements in their physical performance metrics.

While acknowledging the small sample size of this pilot study, these findings nonetheless raise a significant possibility: that exercise could serve as a valuable tool for regulating cellular recycling in ways that actively promote healthier aging. Larger, more comprehensive studies will be indispensable to confirm the consistency of these observed changes and to definitively establish the extent to which they correlate with tangible improvements in 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, highlighting the potential therapeutic promise of this line of inquiry.

Expanding Research Horizons: Exercise, Autophagy, and Healthy Aging

The implications of this research extend far beyond the immediate findings, underscoring the critical need to conceptualize cellular recycling not as a process that uniformly diminishes with age, but as a dynamic and complex system that undergoes intricate modifications throughout life. Future therapeutic strategies targeting autophagy will likely need to adopt a more personalized approach, meticulously accounting for an individual’s age, sex, and the specific cellular context.

To further investigate the potential benefits of exercise in this regard, 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 enable the expansion of their research efforts, fostering a deeper understanding of the intricate interplay between physical activity, autophagy, and the multifaceted process of aging.

Currently, the team is collaborating with the Exercise and Physical Activity Resource Center at UC San Diego. This collaboration is instrumental in designing and executing larger-scale studies that will involve a greater number of participants and incorporate more sophisticated testing methodologies. These enhanced studies aim to rigorously examine how various forms of physical activity influence autophagy, aging trajectories, and overall physical function. The ultimate goal is to elucidate whether targeted modifications in cellular recycling can indeed contribute to the development of effective strategies for promoting healthier aging.

The study was generously supported by funding from multiple esteemed institutions, including the National Institutes of Health (National Cancer Institute and 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 broad scientific and societal interest in this critical area of research. The collaborative efforts of the researchers involved in this seminal study, including additional authors who contributed to its successful execution, represent a significant leap forward in our understanding of cellular maintenance and its profound impact on human health and longevity.