Molecular Stress in Aging Neurons Explained

As the population ages, scientists are urgently exploring why older individuals are more susceptible to neurodegenerative diseases. A new study from the University of California San Diego School of Medicine offers a breakthrough: molecular stress in aging neurons may be the key contributor to disorders like Alzheimer’s disease, dementia, Parkinson’s, and ALS.

Understanding Molecular Stress in Aging Neurons

Using a cutting-edge technique called transdifferentiation, researchers turned human skin cells into aged neurons, mimicking the molecular state of old brain cells. What they found was striking — these aged neurons exhibited significant molecular stress.

Unlike young neurons, aged ones:

• Stopped growing,

• Hoarded untranslated RNA and proteins in “stress granules” outside the nucleus,

• Lacked the RNA-binding proteins essential for stress recovery.

These findings suggest that older neurons are less equipped to handle new stress events, making them more vulnerable to neurodegeneration.

How Molecular Stress Triggers Disease

One key discovery was the behavior of a protein called TDP-43, vital for regulating gene expression. In aged neurons, TDP-43 was mislocalized outside the nucleus — a hallmark also found in patients suffering from ALS and Alzheimer’s disease.

The accumulation of stress and the failure to respond to it are believed to “confuse” neurons, redirecting resources away from essential stress response mechanisms. “It’s the neuronal equivalent of being so stressed that you catch a cold,” said first author Dr. Kevin Rhine.

Implications for Neurodegenerative Disease Therapies

These insights could pave the way for new therapies aimed at preserving RNA function and reducing cellular stress in aged neurons. The next step, researchers say, is identifying the exact source of this stress and developing methods to reverse or prevent its damage.

As Dr. Gene Yeo puts it, “We think aged neurons are prioritizing other proteins and forgetting about the stress response.” Understanding and addressing this forgetfulness could help delay or prevent the onset of devastating neurodegenerative conditions.

For more information: Rhine, K., et al. (2025). Neuronal aging causes mislocalization of splicing proteins and unchecked cellular stress. Nature Neuroscience. doi.org/10.1038/s41593-025-01952-z.