Parkinson's disease causes slowness of voluntary movement.
Paresis is a condition typified by a weakness of voluntary movement , or partial loss of voluntary movement or by impaired movement . Parkinson's disease . Early in the disease , the most obvious are shaking , rigidity , slowness of movement , and difficulty with walking . As the disease progresses and neurons continue to be lost , these medications become less effective while at the same time they produce a complication marked by involuntary writhing movements .