Staring is considered a "change in facial expression", whereby the person doesn't blink as normal.
Another sign of Parkinson's is when one arm doesn't swing as you walk with a little bit of speed.
A stooped posture could also be a sign, as could a frozen, painful shoulder.
Some people may experience numbness, tingling, aching or discomfort in their neck or limbs.
Other could develop a softer voice, smaller handwriting, or an internal feeling of trembling.
Parkinson's disease: Staring could be an early indication of the disease (Image: Getty)
It's possible for a person with Parkinson's to lose their sense of smell, or to become depressed or anxious.