Parkinson's is a progressive disease that causes trembling, rigidity, slowed movement and poor coordination in an estimated 1 million people in the United States, according to the Parkinson's Disease Foundation.

Parkinson's disease is a degenerative disorder of the central nervous system. The earliest symptoms are related to movement and including a tremor, rigidity, slow movements and difficulty walking. Later symptoms can include thinking, sleep, emotional and behavioral problems including dementia.

Parkinson’s disease is one of the most common neurological disorders to affect older people. In patients with Parkinson’s, the nerve cells, or neurons, that produce the neurotransmitter called dopamine are destroyed, causing many different symptoms.

Parkinson's disease is a devastating diagnosis, because while the illness is treatable, it is not curable. Parkinson's disease is marked by progressive degradation of the nervous system, which results in symptoms including tremors, muscle stiffness, slow movements, impaired balance and changes in speech.

A dopamine antagonist is a chemical, medication or drug that prevents the actions stimulated by dopamine. Dopamine is a naturally produced chemical in the body that binds to regions in the brain to help regulate emotions and movement.

Essential tremor is also called benign essential tremor and is, among the 20 different types, the most common. This type of tremor is an unintentional, rhythmic, back and forth muscle movement of one or more parts of your body, but most commonly affects one or both hands.