I do believe that exercise will slow the progression.

Exercise almost completely protected against the loss of these neurons.

Exercise is not going to hurt you. If we were talking about a drug, I'd say wait. But there are no side effects to working out.

Even if we can't reverse things, I think we still hope that we can slow down or even stop the progression.

If we were using ... an experimental drug, I would be the last person in the world to say go get it. But in general, the kind of exercise we're talking about is certainly not going to hurt.