This disease is named after the English doctor, James Parkinson, who described the symptoms in 1817. The symptoms do not usually appear before the age of 50 - the prevalence increases with age and the disease is slightly more common in men than in women.
The brain produces dopamine which transmits impulses between the nerve cells in the part of the brain that partakes in coordinating our movements. In people suffering from Parkinson's disease, at least 60 - 80% of the dopamine-producing brain cells have stopped functioning. This results in the person moving slowly, stiffly and slightly bent forward - but the most characteristic symptom is the shaking arms and hands (the legs can sometimes also be shaking). The shaking is worst when the muscles are relaxed. The earliest symptom is often the decrease or loss of the sense of smell. Another early sign of the disease is called pill-rolling tremor in which the thumb and index finger move quickly towards and away from one another. A reduced swallowing function and an increased saliva production can make the person slobber more easily. In some people, the symptoms start in one side of the body after which they spread to the other side. Problems such as depression, sleeping problems, and reduced mental ability might occur. The course of the disease is highly individual.
The cause of Parkinson's disease has not yet been clarified. Nevertheless, there have been findings of large amounts of defective alpha-synuclein and parkin proteins in Parkinson’s patients. These defect laden proteins lead to injury of the nerve cells. Because loss of the sense of smell is often the first symptom, indicates the cause of the disease may be found in the brain’s smell centre. Parkinson's patients might suffer from a defect in their ability to detoxify the body of certain toxins - but, in short, any kind of impact on the brain that causes it to stop producing dopamine will cause Parkinson's symptoms. The same is the case if the dopamine-receiving cells are blocked.
The factor of heredity has been refused in the past, but it is still debated whether or not inheritance plays a role in the development of Parkinson's disease. Environmental exposures also seem to be a just possibility - possibly in combintaion with a hereditary tendency. Middle-aged men who drink 1 - 2 glasses of pasteurized milk a day seem to double their risk of developing Parkinson's disease later in life. The cause-and-effect relationship is unclear, but it does not seem to depend on the calcium content of the milk. Sequelae from encephalitis and various kinds of poisoning plus certain medicaments with an effect on the nervous system can result in Parkinson symptoms. Some studies indicate that people who have either been directly exposed to pesticides in farm work or who have been indirectly exposed from drinking water contaminated with pesticides have an increased risk of developing Parkinson's disease. Exposure to organic solvents and poisoning with heavy metals, manganese, aluminium, and iron, are suspected of being possible causes.
