Neuronal death represents the primary pathology of neurodegenerative diseases such as Alzheimer's and Parkinson’s disease and Amyotrophic Lateral Sclerosis. These diseases usually present with a slow onset and a chronic progression. Various regions of the brain, spinal cord, or peripheral nerves may be affected, leading to functional impairment and neuron loss. Neurodegenerative diseases are often categorized by symptoms that may include impairment in cognition, movement, strength, coordination, sensation, or autonomic control. However, the diagnosis of a specific neurodegenerative disease may be misleading, as there is both clinical and neuropathologic overlap among diseases and existing diagnostic tools are not always accurate. For most neurodegenerative diseases, neuronal dysfunction, such as synaptic loss, may occur long before neuronal death takes place (Soto, 2003;Shastry, 2003;Aguzzi and O'Connor, 2010).