Methods for treatment and/or prevention of nerve degeneration in mammals using aza-peptide epoxide caspase inhibitors are provided. Aspects of the present disclosure include aza-peptide epoxide compositions to treat or prevent diseases, for example stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, neuropathies, Huntington's disease, dentatorubropallidoluysian atrophy, spinocerebellar atrophies, spinal bulbar muscular atrophy, diabetes, amyotrophic lateral sclerosis and other motor neuron diseases. The disclosed methods can be used in combination with calpain inhibitors to treat disease or pathological conditions related to the activity of caspases and calpain associated with a specific disease or condition. Such treatable conditions include stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, neuropathies, Huntington's disease, dentatorubropallidoluysian atrophy, spinocerebellar atrophies, spinal bulbar muscular atrophy, nerve degeneration associated with diabetes, amyotrophic lateral sclerosis and other motor neuron diseases, nerve degeneration secondary to primary demyelinating disorders, among others.