Degenerative diseases of the nervous system (neurodegeneration) is a term used to encompass any of the diseases or disorders which are due to a loss in the function or structure of neurons of the brain or spinal cord. They affect body activities such as balance, movement, talking, breathing, and heart function, amongst others. Many degenerative diseases of the nervous system have no cure, but treatments can improve symptoms and relieve pain.

Causes can include medical conditions such as a tumor or stroke, toxins, chemicals, viruses, or the unknown. Examples of degenerative diseases include Alzheimer disease, dementia, Huntington disease, Parkinson disease, and Creutzfeldt-Jakob disease.