Different types of Neurodegenerative Cascades. The utility of targeting events downstream of any disease trigger will in part be determined by the type of cascade that is established. If a linear cascade (left panel) is established there may be many events that can be targeted that will have equal efficacy. Halting any step in the cascade may stop the cascade. In a branching cascade (middle panel), the situation where a single initiating event triggers multiple insults that then mutually contribute to neuronal death, the efficacy of targeting a single downstream pathway may be much more limited. In the case of a mixed cascade (right panel), in which an initiating event can trigger a complex cascade which may initially be linear and then later branch, understanding the placement of any given insult within cascade may be critical with respect to determining how effective therapies targeting that step will be with respect to slowing or halting neurodegeneration.