Alzheimer’s Protein Transmissible, but Without Clinical Symptoms of Disease

Margarida Azevedo, MSc avatar

by Margarida Azevedo, MSc |

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Blood-brain barrier in early Alzheimer's disease

Researchers at Austria’s MedUni Vienna have found that the protein associated with Alzheimer’s disease (AD), amyloid-β, is transmissible to other brains under very unusual circumstances. However, the clinical symptoms of the disease are not manifested in the affected brains, suggesting that amyloid-β transmission is not able to reproduce the full phenotype of Alzheimer’s. The research paper, “Dura mater is a potential source of Aβ seeds,” was published in Acta Neuropathologica.

Amyloid-β and tau protein aggregate deposits in different areas of the brain tissue are considered hallmarks of Alzheimer’s disease. Recent research has raised concerns due to the suggestion that amyloid-β protein might be transmissible to healthy individuals in the context of brain surgery. Such findings were made during brain tissue examinations from deceased people that had received grafts of dura mater, the thick membrane covering the brain, or human growth hormone.

Researchers examined and compared archived dura mater samples, confirming for the first time that amyloid-β, usually found in cerebral tissue, can also be stored in this membrane. The results confirm previous research that found amyloid-β is transmissible from the dura mater to another brain.

investigators found, however, that the amyloid-β deposits in the affected brains differ microscopically from those usually found in Alzheimer’s disease. In these brains, amyloid-β protein was restricted to the operated tissue, instead of spreading out to other brain regions. Besides differences in morphology and distribution patterns of the deposits, researchers also observed that no clinical symptoms characteristic of Alzheimer’s or tau protein deposits developed.

“The study allows us to obtain a balanced opinion of the transmissibility of Alzheimer’s disease,” principal investigator Gabor G. Kovacs said in a press release. “Despite the fact that it looks as if amyloid-β, the protein associated with Alzheimer’s, might be transmissible under very unusual circumstances, the clinical manifestation of Alzheimer’s disease is not transmitted. It is certainly not correct to talk of a transmissibility of the disease.”