Parkinson's disease

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

The disease is a progressive movement disorder of the extrapyramidal system, which controls and adjusts communication between neurons in the brain and muscles in the human body.

The actual cause of Parkinson's disease is not known. Geneticists recently found a defective gene in a few families with extraordinarily high incidences of the disease, but most researchers believe that other factors are also 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: a strong inheritance pattern is only seen in a very small percentage of familial cases. In young-onset patients, however, scientists believe there might be a genetic pattern. It is thought by some that a trigger (environmental, past illness/disorder, trauma, etc.) can start the disease in patients already having a potential 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 production of dopamine, a chemical substance produced by the substantia nigra (in the pathway projecting to the 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 is typically seen and it is this deficiency of dopamine which causes most of the outward symptoms of this disease.

Symptoms may vary among patients, and additionally may vary greatly over time in a single patient, but commonly include:

tremor (while this is the best known symptom, it is not displayed by an estimated 30% of patients),
rigidity (increased tone or stiffness in the muscles),
bradykinesia (slowness of movement),
failing balance,
walking problems.

Additonally, 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,
loss of sense of smell,
oily skin,
difficulty in swallowing.

Symptoms usually only begin to appear after about 80% of the dopamine in the brain has been lost. The level of dopamine will continue to fall slowly over time, with an attendant worsening of symptoms. The disease is not lethal.

It is an invalidant disease, disturbing some important human functions and in some cases resulting in a substantial reduction in quality of life. As in many neurologic diseases, phychological complications are often extremely serious and require the patient's family members and relatives to pay keen attention to the emotional fragility that usually follows the emergence of the disease; indeed, the depression which often results is seen by many as one of the worst aspects of the disease. In some cases drugs are employed, especially in the fight against depression (given that Parkinson's-related depression is mainly induced by a complex of chemical-physical factors). Also, some common side effects of therapy can put the patient in a condition of humble self-consideration. External help is required to control the administration of the prescribed therapy: since patients are often confused or depressed, there is a risk of their improperly implementing the therapeutic regime if left to their own devices, leading to symptoms not being adequately controlled.

Unfortunately, Parkinson's disease is very widespread, and millions of patients are estimated to exist around the world. Cases are reported at all ages, though it is quite rare in people younger than 30; the risk of developing it substantially 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 recent statistics, men are affected slightly more often 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). This is now often supplemented with carbidopa, a substance which prevents levodopa from being metabolized in the gut, liver and other tissues, thus allowing more levodopa to reach the brain and thus allows a reduction in dose, thus reducing the sometimes heavy side effects.

As in many other diseases, the therapy requires a continuing regime of medicines, the dosage of which has to be specifically calculated for each single case and might vary during the evolution of the disease. The treatment is complex and usually consists of a mixture of substances (basically focused on levodopa), some of which compensate side effects of others. Amantadine hydrochloride, Anticholinergics and COMT inhibitors are sometimes prescribed. The therapy can produce side effects and, notably, some medicines might interfere with driving ability. Some foods rich in proteins can disturb the uptake of levodopa, because the same uptake system is used both by proteins and levodopa, and so these foods can reduce the effectiveness of the treatment. However, this can usually be dealt with by redistributing meal times: in many cases it is advisable to move the consumption of proteins towards the evening, so to have symptoms appearing when the patient has less need of mobility. While these therapies are a good attempt at treating the symptoms, they are not a cure - they do not attack the underlying cause of the disease; that is to say, they do not restore the brain's dopamine production. However, the therapy can stop the progression of the disease and some cases are reported of regression. Surgical interventions are currently being researched, but there is insufficient statistical data to draw conclusions yet on their effectiveness.

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 so-called "muscular spiral" is one of the worst side effects of the disease: the muscular rigidity commonly caused by the disease makes it difficult to rest at night, when usually muscles should relax, so the patient cannot sleep well because of muscular rigidity and (not sleeping well) cannot relax muscles, so he has a worse sleep, and so on. This spiral has to be broken by physical exercise and/or therapy.

The current status of the fight against the disease can be summarised as follows: while substantial success has been made in minor fields, and many studies performed of the disease, treatment consists only of symptom management and must still be individually tailored to each patient. Research continues into possible outright cures, including surgical brain cell transplants.

Parkinson's disease does not necessarily affect intellectual integrity, apart from the emotional effects of eventual psychological complications, and in those cases where the patient is still compos mentis, their role in the treatment is fundamental. The patient's cooperation is required in order to provide the physicians with all the details that might help in the making a correct diagnosis and consequent determination the best appropriated therapy. Conversely, it is crucial for doctors to explain the precise extent of the disease's progress, and provide as much information as possible about the prescribed therapy, how the symptoms and side effects can be reduced. Working together in this manner, the patient and doctor can ensure the maximum quality of life for the sufferer.

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 theses Parkinson-Plus diseases can only be diagnosed when other symptoms become apparent after some years. These Parkinson-Plus diseases usually progress more quickly than the typical main illness, and the usual anti-Parkinson's 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.

One famous sufferer of young-onset Parkinson's is Michael J. Fox, who has written a book about his experience of the disease. The film Awakenings (starring Robin Williams and Robert de Niro and based on genuine cases) also deals sensitively and largely accurately with the disease; sadly, the state of the art in treatment remains roughly the same as it was at the time of the events depicted, the 1960s.

External links

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