Regarding chemo damage:

I think this is similar to drug damage (like statins and some others).

The chemo patients don't seem to stay on the forums for long, so I don't see often much progress with them. The statin damage posters don't seem to improve much either.

The neuron has dendrites-- 1) the fine collecting sensing fibers, 2)the cell body where the nucleus lives and the mitochondria, and 3)the axon where signals are sent out.

As Glenn has explained, if the cell body dies... there is no energy producing capability (mitochondria) so then nothing gets sensed or sent up the to brain. Chemo kills cancer cells and normal cells. So I don't want to be a downer, but if enough cells die, then you are out of luck. If they are only damaged, they may repair themselves, and that takes time (and patience).

This all may change with stem cell research and therapy. But I do think it is difficult to predict what will happen with each person, since everyone is so different.