HYDERABAD: Depression and anxiety could be the symptoms leading to Parkinson's disease, says doctors on the occasion of World Parkinson's Day on Sunday. Parkinson's disease is a progressive nervous system disorder that affects the movement of the human body. Symptoms start gradually, sometimes starting with a barely noticeable tremor in just one hand. Tremors are common but the disorder also commonly causes stiffness or slowing of movement. (IANS)