Rethinking Conventional Wisdom: Could Overactive Neurons Accelerate Aging?
Researchers at Nagoya University in Japan have found that age-related cognitive decline is more closely linked to excessive neuronal activation over time rather than a simple reduction in activity. Their study, published in Proceedings of the National Academy of Sciences, suggests that interventions—such as dietary changes—could help slow cognitive aging by limiting this hyperactivity.
A healthy brain depends on well-connected neurons that communicate efficiently. Traditionally, scientists believed that cognitive decline stemmed from a gradual decrease in neuronal activity. However, this study challenges that assumption, emphasizing overactivation as a key contributor to neurological aging.
In humans, certain neurons have been observed to become hyperactive with age. To explore the link between this phenomenon and cognitive decline, Associate Professor Kentaro Noma and his team conducted experiments on nematodes, a type of microscopic worm.
Using Nematodes to Investigate Aging
“We used Caenorhabditis elegans, a one-millimeter-long nematode with a two-week lifespan,” Noma explained. “These worms exhibit various behaviors controlled by their 302 neurons. Since C. elegans shares many genetic and neurological mechanisms with humans, we hypothesized that its cognitive aging process could provide insights into human brain function.”
The researchers focused on C. elegans’ ability to learn through association, a behavior called thermotaxis. When raised in a food-rich environment at 23°C, the worms would later gravitate toward that temperature. However, when raised without food at 23°C, they avoided it—indicating learned behavior.
“Our earlier research showed that C. elegans’ ability to learn declines with age, leading us to believe that neuronal activity weakens over time,” said Binta Maria Aleogho, the study’s first author. “However, our latest findings reveal that the activity of key learning-related neurons, AFD sensory neurons and AIY interneurons, remains largely unchanged with age.”
Neuronal Hyperactivity and Aging
To further investigate, the researchers selectively removed six types of neurons involved in associative learning. Unexpectedly, when they removed either AWC sensory neurons or AIA interneurons, aged nematodes regained their ability to perform thermotaxis.
Further analysis revealed that AWC and AIA neurons become excessively active with age. “This hyperactivation disrupts normal neuronal networks, preventing proper thermotaxis behavior,” Noma explained.
Importantly, the team discovered that modifying the worms’ diet reduced neuronal hyperactivity and preserved cognitive function. “If dietary changes can mitigate age-related neuronal overactivation in C. elegans, similar strategies might help slow brain aging in humans,” Noma suggested.
“Our research shifts the focus from declining neuronal activity to the damaging effects of excessive activation,” Noma concluded. “We will continue studying C. elegans to uncover ways to counteract neuronal hyperactivity and improve brain function. Understanding these mechanisms could provide valuable insights into human cognitive aging.”
Read Original Article: Scitechdaily
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