What Are Amyloid Plaques?


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Amyloid plaques are accumulations of a fragmented protein product, known as beta-amyloid, in the brain that are associated with the development of Alzheimer's disease, writes the National Institute on Aging. These plaques result from the accumulation of beta-amyloid fragments that stick to one another in the spaces between neurons, though it is unclear whether or not the plaques are responsible for the symptoms of Alzheimer's disease or are a by-product of the brain attempting to clear the protein fragments away.

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Dr. Alois Alzheimer, in 1906, first described Amyloid plaques, according to the NIA. He observed these plaques during autopsies of individuals with age-related cognitive decline; their observance led to the definition of the concept of Alzheimer's disease as a distinct condition. Though usually associated with aging, it is also possible for people with certain genetic disorders to develop amyloid plaques earlier in life as part of early-onset Alzheimer's disease.

The fragments of beta-amyloid that accumulate in amyloid plaques originate from a protein known as amyloid precursor protein, reports the NIA. This protein is a normal component of the cell membrane of neurons and is cleaved apart by enzymes as part of normal metabolic processes. However, if a specific enzyme, beta-secretase, cleaves APP, the resultant fragments have the ability to stick together and produce plaques.

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