Not just in the brain
Scientists have found risk factors for Alzheimer's disease outside the brain
Natalia Pelezneva, Naked Science
Alzheimer's disease is one of the most common neurodegenerative diseases in the world. For a long time it was believed that the processes leading to the development of the disease begin only in the brain itself. However, the authors of the new work suggested that these processes may originate in other organs. This fact will help in the development of new drugs against the disease. Such drugs will affect other organs, preventing destructive processes from reaching the brain.
One of the characteristic manifestations of the disease is the accumulation of amyloid plaques in the brain tissues. These are dense clusters of Aß42 protein (one of the beta-amyloids) folded into beta folds. Researchers have suggested that the blood can transfer beta-amyloids formed in other organs to the brain. To test this hypothesis, the scientists used two types of mice: healthy and genetically modified. The second group was prone to the formation of large amounts of beta-amyloids in the body.
Healthy animals and mutant mice were surgically "connected" in pairs - so that a common circulatory system was formed. This method is called "parabiosis". The animals lived in this state for a year. During this time, amyloid plaques formed in the body of healthy mice. Also, structures resembling neurofibrillary tangles have appeared in their brains – this is another type of protein accumulation and another sign of Alzheimer's disease in humans. The researchers noted several other signs similar to the manifestations of the disease: destruction of brain cells, inflammation and small hemorrhages.
It is known that beta-amyloids are formed not only in the brain, but also in muscles and blood vessels. The precursor substance of beta-amyloid (amyloid precursor protein, APP) occurs in many organs. According to the authors of the new work, their study showed for the first time that such "external" beta-amyloids are able to influence disorders in the brain.
One of the authors of the work Weihong Song comments: "The hemato-encephalic barrier weakens with age. This allows more beta-amyloids to enter the brain, supplementing the volume that is produced in the brain itself and accelerating the deterioration of the condition."
A study by Bu et al. Blood-derived amyloid-β protein induces Alzheimer's disease pathologies published in the journal Molecular Psychiatry.
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