Historians have found evidence of the disease as far back as 5000 B.C. It was first described as "the shaking palsy" in 1817 by British doctor James Parkinson. Because of Parkinson's early work in identifying symptoms, the disease came to bear his name.
In the normal brain, some nerve cells produce the chemical dopamine, which transmits signals within the brain to produce smooth movement of muscles. In Parkinson's patients, 80 percent or more of these dopamine-producing cells are damaged, dead, or otherwise degenerated. This causes the nerve cells to fire wildly, leaving patients unable to control their movements. Symptoms usually show up in one or more of four ways:
This diagram of the brain shows several structures related to Parkinson's disease. Basal ganglia affect normal movement and walking; substantia nigra are types of basal ganglia that produce the neurotransmitter dopamine, which sends messages that control muscles. The globus pallidus is part of a larger structure connected to the substantia nigra affecting movement, balance and walking. The thalamus serves as a relay station for brain impulses, and the cerebellum affects muscle coordination.
Though full-blown Parkinson's can be crippling or disabling, experts say early symptoms of the disease may be so subtle and gradual that patients sometimes ignore them or attribute them to the effects of aging. At first, patients may feel overly tired, "down in the dumps," or a little shaky. Their speech may become soft and they may become irritable for no reason. Movements may be stiff, unsteady, or unusually slow.
Basic PD research over the last several decades, including genetics, molecular and cellular biology, characterization of neural circuitry, brain anatomy, and neurochemistry, has formed the basis of therapeutic research being currently pursued for PD. While the causes of PD are still not fully understood, the most prevalent theories suggest that toxic accumulation of protein in cells, dysfunctional protein clearance, and oxidative stress that leads to cell death are primary causal pathways. There is now genetic evidence for each of these pathways, and a prevailing research strategy is to identify points in these pathways that could be exploited for therapeutic benefit.
Today's basic science research continues to span a diverse array of fields, from genes and molecules, through cells and physiological systems, to the role of the environment and its interaction with genetic susceptibility. It is expected that these studies will continue to inform preventive strategies and better treatments for PD in the future.
The Genetics and Cell Biology of Parkinson's disease
One of the most remarkable transformations in PD research over the last decade was the identification of the first gene to be associated with PD, -synuclein. The discovery that genetic mutations could cause PD brought a sea change to a field that had previously focused only on environmental causes of the disease. Since the discovery of alpha synuclein in