In the later stages of the disease, a person with Parkinson's may have a fixed or blank expression, trouble speaking, and other problems. Some people also lose mental skills (dementia). People usually start to have symptoms between the ages of 50 and 60.ore importantly, not everyone with a tremor has Parkinson's disease. Tremor often starts in just one arm or leg or on only one side of the body. It may be worse when you are awake but not moving the affected arm or leg.