Parkinson's disease (PD) is currently recognized as one of the most common neurological conditions. PD is a slowly progressing neurodegenerative disorder that afflicts around 1.5 million people in the U.S. alone, with 50,000 to 60,000 new cases diagnosed each year. Worldwide, it is estimated that approximately five million people have PD.
The signs and symptoms of PD can be divided into two distinct categories, motor and non-motor, depending on whether they are related to body movement abnormalities or not.
Motor symptoms, which primarily affect the movements of the body, are the most obvious and well-known clinical features of PD. The chief motor symptoms are slowness of movement (bradykinesia), tremor, muscle stiffness (rigidity), and in later stages of the disease, poor balance (postural instability).
Early on these symptoms are usually mild and confined to one side of the body. However, over the years as the disease progresses, the symptoms worsen, spread to another limb from the same side of the body and eventually to the other side, becoming increasingly impairing. While symptoms usually progress slowly, this can vary from one person to another.
Motor symptoms are usually preceded by non-motor symptoms that include: depression, loss of smell (anosmia), constipation, and vivid dreaming (REM-behavior disorder). However, these individual symptoms are very frequent in the general population, the most likely to precede the motor symptoms is the REM-behavior disorder.
The UC San Diego Department of Neurosciences and movement disorder group are involved in studies searching for markers that could help diagnose PD at earlier stages.
It is now widely recognized that PD is a complex disorder with many non-motor manifestations (including neuropsychiatric) in addition to its better-known motor symptoms. These non-motor symptoms affect the person's mood (e.g., depression), senses (e.g., smell, taste), and ability to think quickly. The most bothersome non-motor symptoms are: cognitive impairment and eventual dementia, depression, fatigue, drop of blood pressure when standing, and urgency to urinate. PD patients also complain of olfactory dysfunction and pain in affected limbs.