Methods of treating or preventing axonal degradation in neuropathic diseases in mammals are disclosed. The methods can comprise administering to the mammal an effective amount of an agent that acts by increasing sirtuin activity in diseased and/or injured neurons. The methods can also comprise administering to the mammal an effective amount of an agent that acts by increasing NAD activity in diseased and/or injured neurons. Also disclosed are methods of screening agents for treating a neuropathies and recombinant vectors for treating or preventing neuropathies.