People who live into their 80s and 90s with good memory tend to grow more new brain cells than their peers, a new study reveals.
These “super-agers” possess more fertile brains compared to peers with Alzheimer’s disease that witness negligible new nerve cell growth in later years, researchers from the University of Illinois College of Medicine in Chicago say.
Nerve cells support almost every human function. In some regions of the brain, such as the memory centre hippocampus, new neurons are spawned throughout one’s life.
Studies in primates had previously shown that nerve cell growth was linked to stronger memory formation in later life. The new study reveals this kind of neurogenesis occurs in humans as well.
The new study analysed donated brain samples from five groups of people – healthy young adults, healthy older adults, super-agers, people with mild or early dementia, and Alzheimer’s patients.
The super-ager brains came from donors aged 80 or older with proven “exceptional memory skills”.
The researchers assessed three kinds of hippocampus cells – stem cells with potential to evolve into neurons; cells on the way to becoming nerve cells called neuroblasts; and immature neurons just shy of becoming functional nerve cells.
“Think of the stages of adult neurogenesis like a baby, a toddler and a teenager. All are signs that the hippocampi are growing new neurons,” Orly Lazarov, an author of the study published in the journal Nature, explained.
The researchers found that Super-agers more actively produced new nerve cells than their counterparts, indicative of their distinct memory “resilience signature”.
“Super-agers had twice the neurogenesis of the other healthy older adults,” Dr Lazarov said.
“Something in their brains enables them to maintain a superior memory. I believe hippocampal neurogenesis is the secret ingredient, and the data support that.”
The study also found that people living with early-stage cognitive decline, right before dementia symptoms start to appear, had minimal new nerve cell growth. And the brains of those diagnosed with Alzheimer’s disease generated almost no new neurons.
Scientists hope that further research to understand the full picture of nerve cell growth can lead to targeted therapeutics to preserve memory.
“Understanding how some people naturally maintain neurogenesis opens the door to strategies that could help more adults preserve memory and cognitive health as they age,” Ahmed Disouky, another author of the study, said.
