In the course of aging the brain is subject to many insults, particularly the accumulation of Beta-Amyloid and oxidative damage. These or other stimuli can initiate the process of apoptosis. In apoptosis the cell initiates a program that causes its own destruction. As illustrated in the diagram, if the cell is subject to minor insults and is generally healthy, itwill probably recover and not degenerate. If, on the other hand, it is subject to a series of insults or a chronic state of adverse injuries it may reach the threshold for the initiation of the program and undergo apoptosis. In a state of poor health the cell will be more vulnerable to the initiation of programmed cell death. As shown in the Diagram, the accumulation of various insults (arrows 1,2,3) is what ultimately causes the cells demise.