Millions of people carry APOE4, the strongest known genetic risk factor for Alzheimer's disease, and new research suggests this gene variant may begin altering brain activity well before memory problems appear. Scientists at Gladstone Institutes have mapped a molecular chain linking APOE4 to early brain hyperactivity and found a way to reverse the changes in mice.
What the Research Found
In a study published in Nature Aging on August 23, 2026, researchers studied mice carrying APOE4 and compared them with mice carrying the lower-risk APOE3 variant. They found that in young APOE4 mice, a protein called Nell2 was overproduced. This increase caused hippocampal neurons—critical for memory—to shrink and become unusually excitable. The most hyperactive young mice later showed the worst spatial memory deficits.
Remarkably, when the researchers reduced Nell2 production in adult APOE4 mice, neurons returned to normal size and firing patterns, even in older animals. “This is the first study to directly examine what APOE4 does to neuron function at different ages,” said senior author Misha Zilberter, PhD. “We found fundamental changes in brain circuits in young mice that still had normal learning and memory, and importantly, those changes predicted later cognitive decline.”
Why It Matters
APOE4 is carried by about one in four people and appears in 60–75% of Alzheimer’s patients. The finding that APOE4 accelerates a process resembling normal aging—neurons becoming hyperactive and shrinking earlier—could explain why carriers are more vulnerable to dementia. It also highlights a potential new drug target: if a therapy could reduce Nell2, it might prevent or delay Alzheimer’s in high-risk individuals.
For anyone concerned about their brain health, this research underscores that Alzheimer’s-related changes begin decades before symptoms, reinforcing the importance of early monitoring and lifestyle interventions.
What You Can Do
While these findings are in mice, they suggest that maintaining brain health early in life may be key. You can track your cognitive performance over time using validated tests, stay physically active, eat a Mediterranean-style diet, and engage in challenging mental activities. If you carry APOE4, discuss regular cognitive check-ups with your doctor.
Source: ScienceDaily Mind & Brain
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