Neurodegeneration

Neurodegeneration is the progressive loss of structure or function of neurons, including death of neurons. 
Many neurodegenerative diseases – including amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease, and Huntington's disease.
Such diseases are incurable, resulting in progressive degeneration and/or death of neuron cells. 
There are many parallels between different neurodegenerative disorders including atypical protein assemblies as well as induced cell death. Neurodegeneration can be found in many different levels of neuronal circuitry ranging from molecular to systemic.