Scientists from the University of Edinburgh told the BBC that in the future it may become possible to prevent the onset of the disease or at least halt its progression, and in the more distant future—to cure people who have already begun to develop symptoms.

Despite these optimistic forecasts, they stressed that because of the extraordinary complexity of the human brain, confidence in success will only be possible after the results of clinical trials are obtained.

To help me understand how close scientists are to a breakthrough, I was invited to attend a brain operation—right at the cutting edge of dementia research.

I am standing in surgical scrubs in an operating theatre at the Royal Infirmary of Edinburgh. The intense focus of a dozen people around me creates an atmosphere of calm, despite the cacophony produced by medical equipment constantly beeping and humming.

The patient on the operating table is under sedation. On large screens above him, I see an MRI scan of his brain. It is impossible not to notice a large, bright white mass—a tumor. The cancer began in the intestine and then spread to the brain tissue.

“It’s not on the surface of the brain, so we need to make an opening in the cortex,” explains Professor Paul Brennan, professor of neurosurgery. “It has to be as small as possible, but large enough for us to reach the tumor.”

The cortex is the outer layer of the brain responsible for speech, memory, and thinking. The inner regions of the brain are softer, but the cortex must be cut.

Using a surgical drill, Professor Brennan removes a fragment of the skull. The exposed brain, pink and richly supplied with blood, gently pulses in time with the heartbeat.

Standing beside me is Dr. Claire Durrant, an Alzheimer’s disease researcher from the University of Edinburgh. In her hands is a container filled with ice-cold artificial cerebrospinal fluid that mimics the natural fluid bathing the brain and spinal cord.

In most brain operations, the removed piece of cortex is considered medical waste and simply discarded. But Edinburgh is one of the few centers in the world where, with the patient’s consent, this tissue is preserved for dementia research.

When the moment comes, everything happens very quickly. Professor Brennan places a piece of brain tissue—about the size of a thumbnail—into the container to keep it viable.

Then, after briefly thanking the doctors, we change clothes and head across the city to the university.

I can’t shake the thought that just minutes earlier, this piece of brain tissue was involved in shaping the thoughts and fears of the person undergoing surgery.

“I’m always aware of it, every single time: what we receive is a precious gift that someone gives us on what may be the hardest day of their life,” Dr. Durrant tells me.

Her laboratory is one of the few in the world that works with living brain tissue from adult humans, studying the mechanisms of dementia and other diseases.

“By developing these technologies, we hope to move closer to a world free from many devastating neurological diseases,” she says.

In the United Kingdom, around one million people suffer from some form of dementia, and Alzheimer’s disease is the most common.

But can it ever be cured?

Dr. Durrant’s team is trying to answer that question by studying the fundamental biology of Alzheimer’s disease.

Key unknowns remain: there is still no definitive explanation for why, in Alzheimer’s disease, the connections between neurons—so-called synapses—are destroyed.

Four scientists preparing the brain tissue sample in the lab work in perfect coordination, like a Formula 1 pit crew—a fitting image given that the research is funded by the charity Race Against Dementia, founded by Formula 1 legend Jackie Stewart.

First, the brain sample is embedded in a jelly-like medium. It is then sliced into sections 10–20 cells thick and placed in special incubators to keep the tissue alive.

These slices are then exposed to toxic proteins—amyloid and tau—that accumulate in the brains of people with Alzheimer’s disease. This makes it possible to observe how synapses are destroyed and to determine whether this process can be stopped.

Everything Dr. Durrant has seen so far convinces her that curing Alzheimer’s disease is a difficult task—but by no means an impossible one.

“The data we have so far suggest that this is very clearly a disease—and as we know from experience, diseases can be treated and even cured. Perhaps one day we will find evidence that Alzheimer’s disease is inseparable from human nature itself, but at the moment, I don’t see that,” Dr. Durrant says.

“I have never seen as much hope for success in Alzheimer’s research as I see now. I truly hope that within my lifetime we will witness real, meaningful change,” she adds.

Glimmers of hope have emerged thanks to two drugs—lecanemab and donanemab—which slow the progression of Alzheimer’s disease.

From a scientific perspective, this represents a significant achievement. However, in real clinical practice, some specialists consider the effect of these drugs to be too modest. Neither drug is funded by the UK’s National Health Service (NHS).

Nevertheless, Professor Tara Spires-Jones, director of the Centre for Brain and Neural Sciences at the University of Edinburgh, believes that these two drugs have “opened the door” to solving Alzheimer’s disease.

She meets me in her laboratory, sitting behind a heavy, theatre-like curtain. She blocks out the light so she can work with a highly sensitive confocal microscope that uses lasers to illuminate brain samples.

Professor Spires-Jones studies the role of star-shaped immune cells—astrocytes—in Alzheimer’s disease. Her work illustrates an increasingly widespread idea that treating Alzheimer’s will likely require a multi-pronged approach.

Both drugs—lecanemab and donanemab—target the toxic, sticky protein amyloid. Clinical trials are also underway for drugs that target another protein, tau.

In addition, a growing understanding of the role of the immune system, inflammation, blood vessel health, and the interaction between genetics and the environment is helping to deepen insight into the nature of Alzheimer’s disease.

Professor Spires-Jones believes there are three key stages ahead.

In the short term, the development of drugs that can significantly slow or stop disease progression.

Then, tools for the complete prevention of dementia.

And in the more distant future, a way to cure those who already have symptoms—though she acknowledges this will be much more challenging.

According to the scientist, a true life-changing breakthrough in treatment is still five to ten years away. People could “genuinely return to normal life” if the disease is detected early enough.

However, despite scientists’ optimism, all of this still needs to be proven through research and clinical trials.

“The human brain is so phenomenally complex that we must first and foremost test how this works in people,” Professor Spires-Jones says.