What are plaques and tangles?
Being a neurodegenerative disease, there has to be a way in which the neurons are dying. That, in the case of Alzheimer’s, seems to be by senile plaques and neurofibrillary tangles.
Senile plaques are when a protein called beta amyloid fragments and builds up between nerve cells. Normally a byproduct of aging, an abnormal amount of the protein is one of the physiological markers for Alzheimer’s.
Neurofibrillary tangles are another protein, called tau, a twisted fibrous protein, that groups together around the nerve cells. Their normal purpose seems to be to assist in the formation of microtubules, which help form cell walls. But when damaged, tau disconnects from its normal cells and clumps together.
How these two effects, plaques and tangles, contribute to Alzheimer’s is still not fully known. The tangles, for example, may even be the body attempting to protect against further damage. What is known is that the nerve cells so entangled are dead and dying.
Both of these proteins, acting improperly in this way, damage and even kill nerve cells. They also exist in the brain for a decade or more before Alzheimer’s shows its symptoms. Cause or not, it is still linked to the disease.