Scientists switched the Alzheimer's gene 1 in 4 people carry

1 in 4.

That is how many people carry the gene that raises the risk of Alzheimer's disease more than any other known gene. Scientists in England have just found a way to turn that gene into the safer version that most other people already carry, inside living cells.

The gene is called APOE4. The safer version almost everyone else carries is called APOE3. Researchers at the University of Bristol, led by Dr Kevin Kemp, converted one into the other in a lab, and they say the method could one day work inside a real, living brain.

Photo: explorebiology / Wikimedia Commons, CC BY 4.0

The gene that raises your risk, and the one that doesn't

APOE4 does not cause Alzheimer's on its own. It raises the odds of getting it, more than any other gene scientists have found so far. People who carry two copies of it face the highest risk of all.

APOE3 is the common, lower-risk version. Most of humanity carries it. The Bristol team's idea is simple to say and hard to do: Change the risky copy into the safe one, inside someone's own brain cells, rather than fight the damage after it starts.

Dr Kemp's team worked with human immune blood cells so their results would look as close to a real human response as possible. They found the conversion had little effect on the rest of the cell's DNA, which matters for any future safety check.

Every 2026 Alzheimer's gene finding, pulled into one place

Four separate pieces of work came out in 2026, each from a different angle. Nobody else has lined them up side by side.

How would doctors ever get a new gene into someone's brain?

The Bristol team says their method could be given through the bloodstream, the same way a normal injection works, rather than through brain surgery.

Read nextApple's 13 October launch: Time, products and prices

From there, it would need to cross the blood-brain barrier, a tight wall of cells that keeps most medicines out of the brain. Many Alzheimer's treatments have failed for exactly that reason. The team says their approach is built to get past that wall and reach the whole brain, not just one spot.

The research has not been tested in people yet. The Bristol team describes it as a major step towards a gene therapy, and says the results suggest it could be suitable for future clinical use, but no human trial has started at this stage.

What happens inside the brain once the gene is switched off and on?

A second piece of Bristol work looked at a different cell type, called astrocytes, which support and feed brain cells. When researchers switched on one gene inside astrocytes in mice, three things changed.

The mice built up fewer of the sticky amyloid plaques that clog the brains of people with Alzheimer's. They showed less inflammation in brain tissue. And they did better on memory tests than mice without the switch.

None of this proves the same will happen in a person. Mice are not small humans, and Alzheimer's in mice is built artificially, not grown over decades the way it is in us. But it gives the Bristol team a second angle pointing the same direction as their gene-conversion work.

Trending nowBootlegger data leak: The locked dashboard that was never locked

People who want to understand how researchers test memory and brain protection in other conditions can see a similar pattern in work on whether eight hours of sleep actually protects an ageing brain, where the protective effect also showed up before anyone fully understood why.

Photo: Bobjgalindo / Wikimedia Commons, CC BY-SA 4.0

Why do some people carry the risky gene and never get sick?

Some people carry the high-risk APOE4 gene their whole lives and stay sharp into their 80s. Doctors have never had a clean answer for why, so researchers at Columbia University went looking in October 2026.

The Columbia team found a rare mutation that appears to protect the brain from the harmful protein buildup linked to Alzheimer's. It shows up in a small number of people, and it seems to work like a shield the rest of us do not have.

The reason this matters goes beyond the lucky few who carry it. If scientists can work out exactly how that natural shield works, they may be able to copy it in a future treatment, instead of inventing one from nothing.

Brain research keeps turning up this pattern, where the body's own rare exceptions point the way forward. It shows up in how often a multiple sclerosis diagnosis turns out to be wrong too, where a small group of mistaken cases forced doctors to rethink the whole test. And it echoes other findings on everyday habits that quietly protect the brain, like the research on dancing and exercise easing symptoms linked to brain health.

So could this actually stop Alzheimer's one day?

Nobody can promise that yet, and nobody at Bristol or Columbia is claiming to have a cure. What they have is something rarer in Alzheimer's research: Four separate findings, from two continents, all aiming at the same gene from different directions in the space of a single year.

A gene carried by 1 in 4 people, long treated as a life sentence written at birth, just showed scientists it can be changed. Somewhere out there, a small number of people have been carrying a natural answer to that gene their entire lives without knowing it. The race now is to find out exactly how they do it, and whether the rest of us can borrow the trick.