History of PD
First described in 1817 by English physician James Parkinson as a "shaking palsy," Parkinson’s Disease (PD) is a progressive neurological disorder of the brain that results from a loss of cells that produce dopamine.
Loss of this neurotransmitter dopamine causes neurons to fire out of control, leading to the symptoms of PD -- instability of posture or balance, gait difficulty, stiffness or rigidity of the arms, legs or neck, general slowness of movement and tremors or trembling. Other symptoms may include depression, mental confusion, difficulty writing and speech problems.
According to Brian Hurwitz, in an anlysis on the National Institutes of Heatlh website:
"James Parkinson's Essay on the Shaking Palsy (1817) has long been considered the foundational text of the disease which now bears the author's name."
Hurwitz's article titled "Urban Observation and Sentiment in James Parkinson's Essay on the Shaking Palsy (1817)" was published in 2014.
You can get Parkinson's original essay, published in 1817, from Project Gutenberg. Both the analysis on the NIH web site and the original essay at Project Gutenberg are available for no charge.