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In the brains of people with Alzheimer's disease, the protein amyloid beta accumulates in plaques, which has long been considered a hallmark of the disease. However, not everyone with plaques develops symptoms. This has made it difficult to understand exactly what role the plaques play in the progression of the disease.

The study, published in the journal Nature Communications, presents a method that makes it possible to analyze both the structure and chemical composition of individual plaques in brain tissue. Using AI and imaging techniques, the researchers were able to identify a specific type of plaque – known as coarse-grained plaques – that only occurred in patients diagnosed with Alzheimer's, not in people with plaques but without symptoms.

AI for image analysis

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Jörg Hanrieder, professor of analytical neurochemistry at the Sahlgrenska Academy at the University 91̽��, is one of the study's lead authors:

“We saw that this type of plaque was completely absent in symptom-free individuals with amyloid in the brain. Our method makes it possible to link certain types of plaques to symptoms and disease progression in a more precise way,” he says.

The study combined advanced microscopy and mass spectrometry to capture details about the chemical content of the plaques. AI was used to sort and classify the plaques based on their appearance and composition.

The newly discovered plaque type was found to have higher levels of certain variants of the amyloid beta protein, particularly Aβ1-40 and Aβ3pE-40, which have previously been linked to damage to nerve fibers. These plaques also had a clearer element of altered nerve cells, which is associated with symptoms such as memory impairment, reduced thinking ability, language problems, and other signs of dementia.

“We believe that this type of plaque may be particularly harmful to the brain,” says Jörg Hanrieder.

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“Our AI tools, combined with advanced imaging techniques, have great potential to transform the future of clinical pathology,” says Michael Schöll, professor of neuroscience.

In the long term, the method could be used to better understand why some people with amyloid plaques do not develop symptoms – and why others do. The results may also be important for the development of future drugs, particularly those targeting specific forms of amyloid.

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