Main Characteristics of Alzheimer's
Amyloid Plaques
Beta-amyloid is formed from the breakdown of a larger protein called amyloid precursor protein (APP), found in the fatty membrane surrounding nerve cells. Amyloid Plaques form when the beta-amyloid clump together. The beta-amyloid is chemically "sticky", which allows it to gradually build up into plaques. The danger of the formation of these plaques is that the clumps have the ability to block cell-to-cell signaling at synapses. Additionally, they may activate immune system cells that trigger inflammation, thus devouring disabled cells.
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Neurofibrillary Tangles
Abnormal clumps of the protein tau inside neurons, which undergoes abnormal chemical changes that cause it to detach from microtubules and stick to other tau molecules, forming threads that eventually clump together to form tangles. The tau threads then form structures known as paired helical filaments, that can become enmeshed with one another, causing the formation of tangles within a cell. Tau tangles then disrupt the microtubule network, create blocks in the neuron’s transport system, and block synaptic signaling.
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Loss of Neuronal Connections and Cell Death
Neuronal injury and death spread through the brain, connections between networks of neurons break down, and affected regions begin to shrink in a process called brain atrophy. The other factors of AD inhibits communication between neurons, damaging them, even to the point of cell death.
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