A special treatment available to help treat PD is deep-brain stimulation, which involves an implantable device that directly sends electrical signals to the basal ganglia which counteracts the aberrant signaling in Parkinson's.
Species and groups of species which are called aberrant, and which may fancifully be called living fossils, will aid us in forming a picture of the ancient forms of life.
Some of these smaller (if often still huge) problems are attractive targets for intervention in their own right; chronic inflammation, for example, or the build-up of aberrant proteins seen in Alzheimer's disease.