Parkinson's disease (PD) is a progressive neurological disease in which brain cells that produce the neurotransmitter dopamine gradually die off. The result is an increasing loss of control of motor functions and other non-motor symptoms. Although it doesn't usually show up until after the age of 60, PD can afflict younger people, too. A case in point is the popular actor Michael J. Fox, who noticed the first signs of PD when he was only 30 years old.What Is Parkinson's Disease?PD is a progressive neurological condition often starting with tremors. With time, the body can experience a combination of uncontrollable shaking, stiffness and slower movement and difficulty with balance and coordination. Speech, meanwhile, may start to sound slurred or softer than usual. These physical developments may be accompanied by changes in mood, memory, sleep and energy. These symptoms occur due to decreased amounts of neurons transmitting dopamine to your brain and tend to first be noticed after the…