This disease shows its sign and symptoms gradually and often these go unchecked. Most people experience the symptoms of Parkinson's disease on one side of the body at first. After a certain period both, the sides may get affected. Symptoms of Parkinson's disease are as follows: Tremors Slowed down movements Stiffness of muscles Balance disorders Poor posture maintenance Impaired ability of automatic movements like blinking  Changes in speed and tone of voice Changes in handwriting