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Parkinson's disease, is a neurodegenerative disease of the substantia nigra (an area in the basal ganglia), first discovered and documented in 1817 (Essay on the Shaking Palsy) by the English physician Dr. James Parkinson, but pathological and biochemical changes in the brain of patients were identified in the 1960s.

The 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 human body.

It is also commonly called Parkinsonism, by which in reality physicians mostly call minor or derivative forms.

The actual cause of Parkinson's disease is not known. Genetists recently found a defective gene in a few families with extraordinarily high incidences of the disease, but most researchers believe that other factors too should be responsible, and some suspect that the disease might result from the combination of a genetic predisposition and other (perhaps environmental) factors, not yet discovered. Parkinson's disease is not generally considered to be an inherited disorder; only in a small percentage of familiar cases there is a strong inheritance pattern, but this does not regard the majority of patients. In young-onset patients, however, scientists believe there might be a genetic pattern. It is reputed that a trigger (environmental, past illness/disorder, trauma, etc.) can start the disease in patients already having a potencial tendency to develop it; cases have been recorded in which the starting factor is very likely to have been an emotional or a psychological trauma.

Parkinson's disease affects the process of producing the dopamine, a chemical substance produced by the substantia nigra (in the pathway projecting to globus pallidus, both of which are major components of the extrapyramidal system) that regulates the coordination and the correct performance of some human simple activities like deambulation or other common movements, enabling people to move normally and smoothly. In Parkinson's disease a severe shortage of dopamine typically is seen and, in a word, the deficiency of dopamine causes the symptoms of this disease.

Symptoms may vary among patients, and their appearance may be greatly different on single patients, as well, but commonly do include:

• tremor (the best known symptom, even if est. 30% of patients don't show it),
• rigidity (increased tone or stiffness in the muscles),
• bradykinesia (slowness of movement),
• failing balance,
• walking problems.

Accessorily, patients might show

• depression,
• speech problems (vocal cords can also be affected, causing monotonous, soft speech qualities),
• dementia, or short term memory loss, in aproximately 20% of all patients,
• breathing problems,
• stooped posture,
• sleep disturbances,
• dizziness, constipation,
• altered sexual functionalities.
• fatigue.

Parkinson's disease is not lethal. The symptoms usually do not appear until about 80% of the dopamine in the brain has been lost. The level of dopamine will continue to fall slowly over the years, and symptoms will intensify over that time.

Other secondary symptoms which may be seen are loss of sense of smell, oily skin, constipation, swallowing difficulties, et al.

It is an invalidant disease, disturbing some important human functions and in some cases resulting in a lower quality of the patient's life; like in many neurologic diseases, phychological complications are often extremely heavy and require the patient's familiars and relatives to attribute a keen attention to this fragility that usually follows the emergency of the disease. In some cases chemical enforcement is supplied, specially in the fight against depression (mainly inducted by a complex of chemical-physical factors, indeed), that seems to be the perhaps worse common consequence of the disease. Also, some common side effects of therapy can put the patient in a condition of humble self-consideration. An external help is required also to control the correct respect of the prescribed therapy: if the patient is confused or depressed, he/she might follow improperly the therapy and therefore symptoms could not be properly controlled.

Parkinson's disease unfortunately has a very wide diffusion, and patients are estimated in a proportion of millions, all over the world. Cases are reported at any age, even if it is less common and quite rare in people younger than 30; the risk of developing it substancially increases instead with age. It occurs in all parts of the world, with no evidence of distinction for geographical or socio-economical factors. According to recents stats, men would be slightly more often affected than women.

The treatment of Parkinson's disease mainly relates to the verified lack or insufficient production of dopamine, trying to stimulate the natural production of this substance or directly providing it in the form of levodopa (a dopamine precursor, transfomed into dopamine by the brain), now mainly additioned with carbidopa (this other element prevents levodopa from being metabolized in the gut, liver and other tissues, allows more of levodopa to reach the brain and consents a reduction of doses, therefore significantly reduces side effects, which can sometimes be very heavy).

Like in many other diseases, the therapy requires constant assumption of medecines, which dosing has to be specifically calculated for each single case and might vary during the evolution of the disease. The cure is complex, and usually consists of a mixing of substances (basically focused on levodopa), some of which compensating side effects of other ones. Amantadine hydrochloride, Anticholinergics, COMT inhibitors are sometimes prescribed. The therapy can produce side effects and, notably, some medecines might interfere with driving ability. Some foods rich in proteins can disturb the assumption of levodopa, resulting in a minor action on symptoms, because of the same uptake system used both by proteins and levodopa, but this usually only needs a redistribution of meal times: in many cases it is advisable to move the aasumption of proteins towards the evening, so to have symptoms appearing when the patient has less need of mobility. It has to be recalled that, ignoring the precise cause of the disease (really, what stops or slowens the dopamine's production), the therapies currently used are a good attempt to reduce the effects of the disease, but don't remove the cause. The therapy can stop the progression of the disease and some cases are reported of regression too. Surgical interventions are at the moment at a merely research state, with insufficient statistic data.

Regular physical exercise and/or therapy are beneficial to the patient and essential for maintaining and improving mobility, flexibility, balance and a range of motion, and for a better resistance against many of the secondary symptoms and side effects.

The state of current position in the fight against this disease can be correctly described as not essentially different from what in a famous movie with Robin Williams and Robert De Niro (- please add english title -): after many deep studies, and effective successes on minor fields, the "awakenings" described in the film have now been stabilized, yet the therapy needs to be specifically adapted to each single patient. Current research is also analysing the possibility of brain cells transplants.

The role of the patient in the treatment is fundamental: the patient must be correctly informed of the precise extent of the disease's action, therefore he needs to be informed correctly of the fact that following an appropriate therapy, the symptoms and the side effects can relevantly be reduced, consenting a satisfactory quality of life. Parkinson's disease does not necessarily affect the intellectual integrity, if not for the emotional effects of eventual psychological complications. The patient's cooperation is required in order to provide the physicians with all the details that might help in better defining a correct diagnosis and consequently study the best appropriated therapy.

There are other disorders that are called Parkinson-Plus diseases. These include Shy-Drager Syndrome (SDS), Progressive Supranuclear Palsy (PSP) and Olivopontocerebellar Atrophy (OPCA which is also called Multiple System Atrophy). Patients often begin with typical Parkinson's disease symptoms and only after a few years other symptoms finally become apparent and a proper Parkinson's disease diagnosis can be made. These Parkinson-Plus diseases usually progress more quickly than does typical main illness, and the usual antiparkinson medications do not work as well at controlling symptoms.

Secondary parkinsonism (or briefly 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.

External links

• The PD Webring: http://www.pdring.com/
• Useful links: http://www.apdaparkinson.com/links.htm