Illnesses That Affect the Nervous System. 
    These are basically the disorders, but these focus on behavior, mood, etc. 
    Three types of illnesses are: 
    
    -  Bipolar Disorder (but it affects mood), where one can have many mood swings,  mania , and are often depressed after a manic high. 
    -  Alzheimer's Disease, where the main indications of the disease are memory loss and confusion.