Scientists are not absolutely sure what causes Alzheimer’s but plaques and tangles are prime suspects in cell death and tissue loss in the Alzheimer brain.
Plaques are abnormal clusters of chemically “sticky” proteins called beta-amyloid that build up between nerve cells. The most damaging form of beta-amyloid may be groups of a few pieces rather than the plaques themselves. The small clumps may block cell-to-cell signaling at synapses. They may also activate immune system cells that trigger inflammation and devour disabled cells.
Tangles form inside dying cells. Tangles are twisted fibers of a protein called tau. In healthy areas, tau helps keep the transport system on track. But in areas where tangles are forming, the twisted strands of tau essentially disintegrate the transport system so that nutrients and other essential supplies can no longer move through the cells, which eventually die.
Though most people develop some plaques and tangles as they age, those with Alzheimer’s tend to develop far more. The plaques and tangles tend to form in a predictable pattern, beginning in areas important in learning and memory and then spreading to other regions.
Read more about plaques and tangles at www.alz.org/braintour.