Signs of Alzheimer's disease can be detected far earlier than previously thought

The researchers found signs of Alzheimer's at least seven years before plaques becomes visible.

The study suggests that the gold standard for diagnostic imaging in Alzheimer's disease has not been sensitive enough to detect early brain processes associated with the disease.

"We found that structural changes in the brain occur many years before high levels of plaque are seen on PET scans, which is the brain scan currently used to identify the earliest signs of Alzheimer's disease," says James Michael Roe.

He was the lead researcher responsible for the study.

Disease processes begin in the brain before they become visible

Roe explains that the findings may mean that disease processes are already underway in the brain long before they become visible using today's most sensitive imaging tools.

"We found the earliest signal detected on brain scans to date, which could be useful for tracking the disease before symptoms emerge and may help with earlier detection," he says.

The researchers followed healthy individuals with regular brain scans (MRI) over nearly two decades.

Using the imaging data, they were able to calculate precisely when – and in whom – plaques became detectable.

This is groundbreaking

They were then able to go back and examine MRI scans from the preceding decade. They compared brain changes in people who later developed plaque with those who did not.

"The most groundbreaking aspect of this study is that we found structural changes in the brain many years before the first signs of plaque buildup, which is considered to be the earliest sign of Alzheimer's disease," says Anders Martin Fjell.

He is a professor at the University of Oslo's Department of Psychology.

"These are older people who are functioning well cognitively. What is unique here is that we have examined changes in brain structure in the years before the first scan revealed plaque," he says.

This could mean that we need different medications

Fjell emphasises that Alzheimer's disease is extremely difficult to treat.

One reason is that it is so closely intertwined with ageing and is likely triggered by multiple factors, the professor explains.

"These findings suggest that there are brain changes that precede the first detectable signs of plaque accumulation, which is considered the earliest phase of the disease and occurs many years before cognitive symptoms start showing," he says.

Fjell points out that this could have two different implications:

1. That harmful processes either driving or resulting from plaque accumulation are already underway, despite plaques not being detectable by scanning

2. Or that there are other processes giving rise to changes in the brain that occur even earlier than plaque accumulation.

"If the latter is true, it suggests it's important to continue developing drugs that target processes other than plaque accumulation. But we need more research on this," says Anders Martin Fjell.

Reference:

Roe et al. Cortical thickness changes precede high levels of amyloid by at least 7 years, Nature Neuroscience, 2026. DOI: 10.1038/s41593-026-02363-4

This content is paid for and presented by the University of Oslo

This content is created by the University of Oslo's communication staff, who use this platform to communicate science and share results from research with the public. The University of Oslo is one of more than 80 owners of ScienceNorway.no. Read more here.

More content from the University of Oslo:

• 

  Study: Inhaled pain relief is as effective as morphine

• 

  Why does the brain become more vulnerable to Alzheimer's disease with age?

• 

  They receive heroin as medicine – does it help?

• 

  More children are being diagnosed with coeliac disease, diabetes, and Crohn's

• 

  Researchers have studied the use of AI in classrooms: "Technology cannot think for you"

• 

  Expert: Oil is rarely the cause of war