Huntington's disease is a genetic disorder that damages certain nerve cells in the brain. The damage to the cells in the brain becomes progressively worse until areas of the brain no longer function properly. Movement, cognition, and behavior are affected, and early signs include personality changes, mood swings, fidgety movements, irritability and altered behavior. Medication can help manage some of the symptoms, such as irritability or excessive movement. However, there is no cure for Huntington's disease, and progress of the disease cannot be reversed or slowed.