Because of the dopamine shortage in Parkinson's patients, the balance is thrown off because the same amount of acetylcholine is maintained. Huntington's Disease was discovered in 1872. It is caused by a loss of cells in the basal ganglia. Patients with this disease lose the ability to organize, cope with new situations, reason, think, talk, walk, swallow, etc. The disease ends in death, usually by infection, choking, or heart failure.
Doctors encourage patients to keep their weight up because it helps maintain more steady movements.