Parkinson’s Disease - Symptoms, Causes and Treatment
Parkinson's disease is a disease of the central nervous system that affects the brain's ability to control our movements. The disease is named after Dr. James Parkinson, the first doctor to describe it.
Our brain is not only responsible for our thoughts and reasonings, every movement we make, from a simple blink of an eye to the act of walking, is born from an order coming from the central nervous system, which through neurotransmitters reaches its final destination, the muscles.
A group of brain cells, called dopaminergic neurons, are responsible for the production of dopamine, a neurotransmitter that acts to control fine and coordinated movements. Some of our day-to-day activities are so trivial that we never stop to think about their complexity. Drinking a glass of water, for example, requires a great deal of control of our muscles, not only to bring the arm to the glass, but also to hold it steadily, take it to the mouth, just enough for a quantity x of the liquid to reach our mouth. These are called fine movements, which are very dependent on the action of dopaminergic neurons.
Parkinson's disease is characterized by the destruction of these neurons, leading to a shortage of dopamine in the central nervous system and, consequently, to a movement disorder.
The symptoms of Parkinson's disease only arise when about 80% of the neurons are destroyed. The reason for this destruction is still unknown, which causes Parkinson's disease to be considered an idiopathic disease, that is, without definite cause. However, some risk factors have already been identified:
Age: Parkinson's disease is an illness typically of older people, usually starting around age 60. It is rare to find patients with Parkinson's disease before age 40.
Family History: Family members of Parkinson's patients are at increased risk of developing Parkinson's disease.
Male: Parkinson's disease is more common in men than in women.
Cranial trauma: isolated or repetitive, such as boxing dopaminergic neurons.
Contact with pesticides: certain chemicals can cause neurological injuries that lead to Parkinson's.
Signs and symptoms of Parkinson's disease can be divided into 2 categories: motor and non-motor.
1) Motor symptoms of Parkinson's disease
Tremors: they occur mainly when the patient is at rest and improves when the limb moves. This is a feature that distinguishes tremor from Parkinson's disease from tremors that occur from other causes.
In early stages of the disease, the tremor is intermittent and usually goes unnoticed by family and friends. The patient may report a sensation of "internal tremor", as if one of the limbs is shaking, when in fact the tremor is not perceptible to others. The perceptible tremors usually begin in one hand, usually with movements between the index finger and the thumb, as if you were counting money. Over the years the disease progresses and the tremors become more widespread, reaching other members.
Trembling at rest is the initial symptom of Parkinson's disease in 70% of cases. As the disease progresses, virtually all patients will experience some degree of tremor. There are few cases of Parkinson's that do not cause tremors.
As tremor of Parkinson's disease occurs at rest and improves movement, this is not a very disabling symptom, as opposed to bradykinesia.
Bradykinesia: means slowed movements. Bradykinesia is the most disabling symptom of Parkinson's. The patient feels tired, with intense muscular weakness and a feeling of motor incoordination. Simple tasks become very difficult, like buttoning a shirt, typing on the computer, picking up coins in your pocket, or tying your shoes. The patient reports difficulty in initiating any voluntary movement. The patient becomes hesitant and uncoordinated.
Over time, walking becomes a difficult task; the steps become short and slow, the patient has difficulty getting up and feels unbalanced when standing.
Rigidity: stiffness of muscles is another important symptom of Parkinson's disease. Like tremor and bradykinesia, rigidity begins only on one side, generalizing as the disease progresses. The feeling is that the muscles are trapped, often limiting the range of motion and causing pain. One of the typical signs is the loss of swinging of the arms while walking.
Postural instability: our balance while walking or standing depends on the proper functioning of the brain; it is the one that controls our tonus and muscle reflexes that keep our center of gravity stable. The loss of postural stability is a symptom that occurs only in advanced stages of Parkinson's disease, manifesting mainly with regular falls.
Other common symptoms of Parkinson's:
Loss of facial expression (apathetic expression)
Reduced eye blinking
Changes in speech
Increased salivation
Blurred vision
Micrography (calligraphy changes and the letters become small)
In addition to all motor changes, patients with Parkinson's disease may also develop a history of neurological changes such as dementia, sleep disorders, depression, anxiety, poor memory, hallucinations, psychosis, smell, intestinal constipation, difficulty urinating, sexual impotence, slow thinking and apathy.
Complications of Parkinson's disease occur in those individuals who develop dementia or who are severely physically incapacitated. Pneumonia, falls, and aspiration of food are complications that can occur in later stages, which can lead to death. In general, however, the Parkinson's patient does not have much lower life expectancy than the rest of the elderly population. The great problem of Parkinson's is even the great loss of quality of life.
The progression in Parkinson's disease is very variable and there are no symptoms or signs that allow to predict with precision how the disease will evolve in the long term in each patient. However, the review of some studies can provide us with a broad view on the evolution of Parkinson's disease:
In an earlier study conducted between 1949-1964, the proportion of patients who were incapacitated or dead within five years of the onset of the disease was 25%. This number increased to 67% at 9 years, and to 80% among patients with disease for about 14 years. The study also identified a small group of patients with slow progression, maintaining balance, postural stability and absence of severe disability even after more than 20 years of illness.
A similar study was conducted between 2000 and 2012 and identified complications such as dementia, physical disability or death in about 77% of patients with about 10 years of illness.
Several other neurological diseases may present a clinical picture similar to Parkinson's disease, which makes it difficult to distinguish, especially in the early stages of the disease.
The big problem is that there is no complementary examination, either blood or imaging, that provides the diagnosis of Parkinson's disease. The physician only relies on the medical history and physical examination to close the diagnosis, which makes the specialist's experience important.
In general, 2 of the 3 main motor symptoms (tremor at rest, bradykinesia or stiffness) should be identified for diagnosis, associated with an improvement of these with the use of drugs specific for Parkinson's disease. The initial clinical picture is not always clear enough to establish the diagnosis.
There is no cure for Parkinson's disease, however, current treatments are quite effective in controlling symptoms.
One of the most commonly used drugs is levodopa + carbidopa (Sinemet), which is transformed into dopamine within the brain. Several other drugs that mimic the action of dopamine in the brain can be used, among them: bromocriptine, pramipexole and ropinirole.
In addition to drug treatment, regular exercise is important to slow the motor symptoms of the disease.
