Alzheimer's is not thought to be caused by amyloid alone. Experts say that the amyloid buildup has an accomplice in another compound that interferes with nerve function—neurofibrillary tangles. The long axons that extend from a nerve's cell body to connect with other neurons maintain their shape thanks to internal structures known as microtubules. As Alzheimer's progresses, however, the tight structure of these microtubules starts to fall apart. A normal component of nerve cells, a protein called tau, undergoes pathologic changes which are associated with neurofibrillary tangle formation. These neurofibrillary tangles accumulate in the neuron's cell body and, combined with growing deposits of amyloid plaques, start to disrupt the function of nerve cells. These cells eventually die, leading to loss of essential brain functions.

1. As Alzheimer's progresses the tight structure of these microtubules starts to fall apart

2. Tau proteins form filaments which travel to the neuron body

3. Unhealthy neurons packed with tangles cannot communicate with other neurons and eventually die