Answer the following question given this paragraph: 

In addition to ALS and Alzheimer's disease, other serious nervous system diseases include multiple sclerosis, Huntington’s disease, and Parkinson’s disease. T hese diseases rarely, if ever, occur in young people. Their causes and symptoms are listed below ( Table below ). The diseases have no known cure, but medicines may help control their symptoms.


Q: Multiple sclerosis, huntington’s disease, and parkinson’s disease all affect what body system?


A:
nervous system