A study from Sanford Burnham Prebys Medical Discovery Institute challenges the long-held belief that autophagy—the body's cellular recycling system—simply slows down with age. Published in Aging Cell, the research found that autophagic activity can increase, decrease, or stay the same depending on the cell type and the person's sex. For example, recycling activity declined with age in skin cells from male participants, stayed stable in female skin cells, and increased in induced neurons derived from female participants.
The researchers also found that measuring autophagy-related gene expression is not a reliable proxy for actual recycling activity. Cells with higher or lower expression levels did not necessarily show corresponding differences in measured autophagy rates, cautioning against interpretations based on static gene activity alone.
Perhaps most surprising, the team observed that among participants aged 70 and older, greater autophagy activity was associated with poorer physical health markers—including lower aerobic fitness, higher BMI, weaker grip strength, lower metabolism, and higher resting heart rate. This suggests that more cellular recycling is not always a sign of healthy aging.
The study, which involved healthy volunteers aged 23 to 72, also hints that gentle exercise may help restore more youthful autophagy patterns in older adults. The authors emphasize that their findings challenge assumptions and point to a more nuanced relationship between cellular cleanup and aging.