© Shane CollinsA new study finds that SuperAgers produce between two and two and a half times more new neurons than their healthy peers and peers with Alzheimer’s disease, respectively, which may help explain why their memory stays strong with age.
A new study finds that SuperAgers produce between two and two and a half times more new neurons than their healthy peers and peers with Alzheimer's disease, respectively, which may help explain why their memory stays strong with age. Photo by Shane C...
SuperAgers don't just preserve their memory abilities well into their 80s and beyond — their brains continue to generate new neurons in the hippocampus at levels far higher than typical older adults, and even much younger individuals.
That is the groundbreaking finding from a new study led by scientists at University of Illinois Chicago (UIC), who examined, in part, donated brains from the Northwestern University SuperAger Program. SuperAgers are a unique group of adults over age 80 whose performance on tests of episodic memory was equal to or better than that of people in their 50s.
Over the more than 25 years of SuperAger research at Northwestern, scientists have documented biological and behavioral differences in this group, from slower cortical thinning to lifestyle factors such as stronger social engagement. But this is the first study to identify a genetic difference between SuperAgers and typical older adults. The study was published in the journal Nature.
"We've always said that SuperAgers show that the aging brain can be biologically active, adaptable, flexible, but we didn't know why," said co-author Tamar Gefen, associate professor of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and a neuropsychologist at Northwestern's Mesulam Institute for Cognitive Neurology and Alzheimer's Disease. "This is biological proof that their brains are more plastic, and a real discovery that shows that neurogenesis of young neurons in the hippocampus may be a contributing factor."
Human neurogenesis and why SuperAgers stand out
While scientists have long documented ongoing neurogenesis (the creation of new neurons) in animals such as mice, evidence in humans has been mixed.
This study not only confirms neurogenesis happens in healthy human adults, it found SuperAgers produce between two and two and a half times more new neurons than their healthy peers and peers with Alzheimer's disease, respectively, which may help explain why their memory stays strong with age. The scientists also discovered a distinct "resilience signature" in SuperAgers' hippocampi — a unique cellular environment that supports the birth and survival of new neurons.
The human hippocampus
Key cell types linked to cognitive resilience
The study also found changes in two types of brain cells — astrocytes and CA1 neurons — are key drivers of how well cognition and memory hold up as the hippocampus ages.
© Raymond P KesnerThe Hippocampal Network: The hippocampus forms a principally uni-directional network, with input from the Entorhinal Cortex (EC) that forms connections with the Dentate Gyrus (DG) and CA3 pyramidal neurons via the Perforant Path (PP-split into lateral and medial). CA3 neurons also receive input from the DG via the mossy fibres (MF). They send axons to CA1 pyramidal cells via the Schaffer Collateral Pathway (SC), as well as to CA1 cells in the contralateral hippocampus via the Associational Commissural pathway (AC). CA1 neurons also receive input directly from the Perforant Path and send axons to the Subiculum (Sb). These neurons in turn send the main hippocampal output back to the EC, forming a loop
The findings suggest that preserving the integrity of the excitatory synapses — the brain's primary sites of neuronal communication and memory formation — could be a potential target for drug interventions aimed at preventing cognitive decline.
How the study worked:
The scientists examined the hippocampus regions of donated postmortem brains from five groups: healthy young adults; older adults without impaired cognitive functioning; older adults with mild or early dementia; older adults diagnosed with Alzheimer's disease; and SuperAgers.
Led by UIC scientists, the study examined nearly 356,000 individual cell nuclei from the hippocampus using an advanced single‑cell technique — called multiomic single cell sequencing — that can read both gene activity and the accessibility of DNA. This allowed the team to identify different stages of developing brain cells, including progenitor cells (early descendants of stem cells), immature neurons and mature neurons.
I guess I shouldnt be particularly surprised at it being missing.