Parkinson's disease is an incurable, progressive movement disorder of the extrapyramidal system, which controls and adjusts communication between neurons in the brain and muscles in the body.
While difficult to diagnose, it is characterized by 5 primary symptoms (which may occur in different proportions in different patients):
- tremor (shakiness);
- muscle rigidity (stiffness);
- slowness of movement (bradykinesia);
- postural instablity (balance difficulties); and
A form of dementia, or short term memory loss, occurs in aproximately 20% of all Parkinson patients and is a secondary symptom of the disease.
Other secondary symptoms which may be seen are loss of sense of smell, oily skin, constipation, speaking difficulties, swallowing difficulties, et al.
Clinical Depression, a separate and curable mood disorder, occurs in approximately 50% of all Parkinson patients.
There is no definite cure for the disease and medications are usually used to control the symptoms and to improve the quality of life.
The drugs used for this purpose aim at replacing the lacking dopamine and are either its precursor (levodopa) or agonists (substances that bind to the same receptors with dopamine and evoke similar effects).
Secondary parkinsonism is a term used for a symptom constellation that is similar to that of Parkinson's disease but is caused by other disorders or medications. Major reasons for secondary parkinsonism are stroke, encephalitis, narcotics, toxins and carbonmonoxide poisoning.
There are other idiopathic (of unknown cause) conditions as Parkinson's disease that may cause parkinsonism. In these conditions the problem is not the deficient production of dopamine but the inefficient binding of dopamine to its receptors located on globus pallidus.