Study sheds light on Ab deposition patterns in the brain that result from external sources

Alzheimer’s disease (AD) is the result of the accumulation of a protein called amyloid b protein (Ab) in the brain. This protein can build up in both the functional tissues, or “parenchyma” of the brain, as well as in the blood vessels. This could lead to AD which can cause dementia or cerebral amyloid angiopathy (CAA), which can lead to cerebral hemorrhage. It is unclear the reason Ab develops deposits in these regions. New research conducted by a group of researchers from Kanazawa University is shedding light on the deposition patterns that form when Ab is introduced to the brain via external sources.

Ab is found in many different varieties or varieties. Kanazawa’s group investigated whether Ab strains affected the pattern of deposition. To investigate this, they employed an animal model of AD. The most efficient mouse models are those that inject the mouse with brain extracts taken from Alzheimer’s patients, known as “seeding”.

The team seeded the mice with Ab from autopsied patients with different deposition patterns of Ab which included those with AD and CAA and those with both, and those with very little Ab. After a year, the team compared the patterns of deposition between the mice and patients from whom Ab was taken.

Surprisingly, they did not find any connection between the strain of Ab that mice were seeded and the pattern of deposition. All mice showed Ab deposition in their blood vessels and all mice had a higher CAA incidence than mice that were not seeded using Ab regardless of the strain.

The seeding of Ab is not limited to mice. It is well-known that neurosurgeries that involve the use of Ab-contaminated instruments or the administration of Ab-contaminated drugs to patients could result in “iatrogenic Ab pathologies”.

Tsuyoshi Hamidaguchi who is the study’s principal author Tsuyoshi Hamidaguchi, study lead author, states that Ab deposition was detected in blood vessels but not in the brain parenchyma when we examined the brain parenchyma of patients with different Ab diseases. “This could explain why CAA is a major feature of the Ab pathology we observe in iatrogenic transmission cases.”

The researchers also discovered that the amount of Ab deposition induced by brain extracts from the group with less Ab was higher than the amount induced by extracts from the three other groups of patients.

This is significant because patients with little Ab pathology could still cause contamination leading to iatrogenic transmission-;indeed, the early phase of Ab deposition, when little pathology is evident, may in fact be when the transmission risk is highest. It is urgent that we discover ways to inhibit Amyloid b’s seeding activity.

Masahito Yamada, Senior Author

Journal reference:

Hamaguchi, T., and. (2021) Exogenous Ab seeds induce Ab deposits in blood vessels, but not in the brain parenchyma. This is independent of Ab strain-specific information. Acta Neuropathologica Communications.

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Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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