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Completely ordinary inflammations:
"Could be an important piece in understanding Alzheimer's"

Repeated episodes of inflammation may contribute to the accumulation of harmful proteins in the brain, according to a new study.

"Being physically active and eating healthily can contribute to fewer and shorter-lasting episodes of inflammation. This may be one of the reasons why physical activity and a good diet appear to have a certain protective effect,” says Asgeir Kobro-Flatmoen.

(Photo: Anne Elisabeth Næss)

Siw Ellen Jakobsen Siw Ellen Jakobsen Journalist

Published 1 November 2026 - 00:01

Influenza. Gastrointestinal infections. Urinary tract infections.

Our bodies are exposed to many common infections throughout our lives.

Pollen allergies, air pollution, and environmental toxins can also trigger inflammatory responses.

Lack of sleep is another factor that can affect inflammation in the body.

"We now know from other research that inflammation is associated with the risk of developing dementia, including Alzheimer’s disease," says Asgeir Kobro-Flatmoen.

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He is a neuroscientist and head of the Norwegian Health Association’s dementia research centre at the Kavli Institute at NTNU.

A mathematical model

"At the population level, we see that the more episodes of so-called systemic inflammation a person experiences, the greater the risk," the researcher says.

In the new study he led, the researchers did not investigate inflammation directly. Instead, they used existing knowledge about inflammation as the basis for developing a mathematical model.

"Our model shows only one possible chain of causation. It has not yet been confirmed in living humans," the researcher points out.

"This could be an important piece of the puzzle in understanding Alzheimer’s disease," he adds.

Which comes first?

A growing body of research suggests that inflammatory processes are involved in the development of Alzheimer’s disease, confirms Anne Rita Øksengård.

She is a specialist in geriatrics and research director at the Norwegian Health Association. She was not involved in the new study.

However, she points out that it remains unclear whether inflammation helps trigger the disease or whether it develops in response to disease-related changes that are already underway.

Around 70 episodes of inflammation

In the new study, the researchers focused on people between the ages of 50 and 72.

Using research literature and statistics, they estimated how many times a person typically experiences a condition that causes systemic inflammation during this stage of life.

“There are indications that important changes associated with the development of dementia occur during this period. And we are not talking about genetic causes,” says Kobro-Flatmoen.

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“We calculated that we experience around 70 episodes of these inflammatory reactions during this period of life,” the researcher says.

Naturally, the number varies considerably from person to person, he points out.

"That's why we used mathematical methods to investigate many different possible scenarios, varying both the number of inflammatory episodes and how long they lasted," he says.

A possible explanation

The researchers have attempted to find a concrete explanation for why certain nerve cells in the brain are particularly vulnerable to developing Alzheimer’s early on.

"We know these cells are affected very early in the disease process, and we suspect they may be among the places where the disease first develops," says Kobro-Flatmoen, adding:

"We have found a possible explanation, but I want to stress that it is precisely that: a possible explanation."

Their hypothesis is that inflammation may cause nerve cells to produce more of a protein called amyloid-beta. This protein occurs naturally in the brain. In Alzheimer’s disease, it can accumulate and form clumps.

The researchers propose that amyloid-beta may bind to another protein called reelin. Some of the nerve cells affected in the earliest stages of Alzheimer’s disease contain particularly high levels of this protein.

Gradually builds up

According to the researchers’ model, repeated inflammatory episodes may cause these proteins to gradually accumulate inside nerve cells, long before the characteristic plaques form outside the cells.

Their findings suggest that nerve cells with high levels of reelin accumulate more amyloid-beta bound to reelin than cells with lower level of the protein.

"Our model shows that the cells’ system for breaking down the protein can become overloaded. With repeated inflammation, increasing amounts of protein may remain inside the cells. Over time, this accumulation could cause damage," explains Kobro-Flatmoen.

Still only a hypothesis

Reelin is a protein that researchers already know plays a role in learning and memory. But they still know too little about how reelin and amyloid-beta affect each other, Øksengård emphasises.

She therefore believes it is too early to conclude that reelin plays a central role in the development of Alzheimer’s disease.

"This is still a hypothesis," she says.

Øksengård believes more studies, including clinical longitudinal studies, will be necessary.

Portrait of Anne Rita Øksengård. — Researchers were already attempting to treat Alzheimer’s disease with anti-inflammatory medicines in the 1990s and 2000s, says Anne Rita Øksengård.

Testing the theory in rodents

The purpose of developing theoretical models like this one is to generate new, more precise hypotheses that can then be tested experimentally.

"We have already launched a new experimental study in rodents to investigate how inflammation in the brain may affect these processes," says Kobro-Flatmoen, adding:

"We want to see whether what we predict mathematically actually happens in the brains of rodents when they are exposed to different inflammatory processes."

Can we prevent inflammation?

"We know that more inflammatory processes can occur in the body as we get older. If your model is correct, does this mean we should try to reduce such inflammation as quickly as possible?"

Kobro-Flatmoen believes it is difficult to provide specific medical advice on the basis of this study.

However, if their model is correct, it could help explain why physical activity and a healthy diet are associated with better brain health, he believes.

It is also important to follow the recommendations of health authorities and doctors regarding vaccines, the researcher adds.