Iverson's Disease is a chronic and progressive muscular disorder which has been known to affect Humans and Betazoids. The disease causes fatal degeneration of the body's motor skills, but is not known to affect a person's mental facilities. As of 2364, there was no known cure for the disease, and no case of remission was ever recorded.
In 2359, Admiral Mark Jameson was diagnosed with Iverson's Disease. Unwilling to slowly fade away with the disease, Jameson managed to obtain an alien drug from Cerberus II to alleviate the symptoms. While the drug initially proved successful, Jameson's over-reliance on the drug led to his death. (TNG episode: "Too Short a Season")