So it looks like the nerves have a system to get rid of things...

So it looks like the nerves have a system to get rid of things hampering mitochondria and their energy production. It is clear that accumulating iron is one of these problems as was clearly demonstrated by Huang XT et al : Iron-induced energy supply deficiency and mitochondrial fragmentation in neurons. This Huang et al paper also demonstrated that iron chelation did help the energy production. So if there is too much stuff hampering mitochondria and causing stress there is a need to get help by a drug. In the case of iron overload, PBT434 would be perhaps the best option. As we know iron accumulation develops very slowly just as these neurodegenerative diseases. However, in acute bleeding into the brain ( brain injuries, hemorrhages, etc.) iron overload develops rapidly and most likely the natural system has no possibilities to help and so these traumas will speed up the degeneration process.
Things are more complicated than my simplification above as you can read in this Puri R et al paper from National Institute of Neurological Disorders and Stroke,