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Let's talk about Parkinson's disease
Parkinson’s disease is a chronic neurodegenerative disease, which is characterized by a dysfunction in the production of cells in the brain that are responsible for the production of a chemical called dopamine. Dopamine is responsible for muscle activity in our brain, so when its levels are reduced our body movements are severely affected.
The development of Parkinson’s disease is progressive, so as time progresses, the symptoms become more aggressive. Unfortunately, the onset of symptoms is generally associated with a loss of already between 60 to 80% of dopamine-producing cells. The symptoms most associated with this disease are those of motor control, such as tremors and muscle stiffness. Body movements become slower, body posture less stable and the way we walk changes. A large number of non-motor symptoms are also associated, including, for example, sleep disturbances or dementia, anxiety or loss of smell, which may appear before the motor symptoms.
Parkinson’s disease is currently the second degenerative disease with the highest incidence in the world, after Alzheimer’s disease, and affects about 10 million people globally. In Portugal, it is estimated that between 18 and 20 thousand people suffer from this disease, which mainly affects the elderly population, and the incidence before the age of 50 is considered rare. Men, as in Alzheimer’s disease, are more affected by Parkinson’s disease than women.
To date, there is no cure for Parkinson’s disease, nor has any drug been developed that effectively delays or prevents the progression of the disease. However, there are therapeutic treatments that allow the reduction of symptoms and thus allow an improvement in the quality of life of patients.
It is still not possible to pinpoint an exact cause for the onset of Parkinson’s disease. The consensus among physicians and researchers is that this may be the result of a combination of genetic factors, ie a person’s own predisposition, with toxic environmental factors, such as exposure to pesticides and herbicides.
We already have, however, a vast understanding of what happens to a person with Parkinson’s disease. We know that the disease starts when nerve cells (neurons) in a specific small part of the brain (the so-called substantia nigra) begin to die. The neurons in this part of the brain are responsible for producing dopamine, the neurotransmitter responsible for facilitating communication between the neurons responsible for controlling our body movements. When the degeneration of the substantia nigra reaches a certain level and the production of dopamine is reduced to a minimum, motor symptoms begin to appear. According to the National Parkinson Foundation (USA), even before the first motor symptoms appear, between 60 to 80% of dopamine production may have already been lost.
So, we know that cells die, we just don’t know why they die, or why some people develop the disease and others don’t.
Parkinson’s disease is quite complex in the way it affects patients, that is, it does not necessarily affect two people in the same way, the symptoms and the order in which they appear may vary.
Since Parkinson’s disease, as we saw earlier, is caused by a production decrease of the substance (dopamine) that helps control our body movements, the main symptoms of the disease are precisely associated with a loss of control of muscles and movements. Lesser known by the general public are the non-motor symptoms that sometimes appear well in advance of the motor symptoms and can allow an early diagnosis of the disease.
Generally, this progressive disease begins by affecting only one side of the body, especially in times of greater tension. It can affect just one finger, one hand, one arm or one leg. As time progresses and the disease progresses, the affected area begins to expand, with symptoms becoming visible on both sides of the body, although the side that was initially affected will be the side with the most intense symptoms. .
Among the most prevalent motor symptoms are the following:
- Tremor (characterized by involuntary movement or shaking of a limb, head, or entire body) — This is the most recognized symptom of Parkinson’s disease. About 75% of patients with this disease report this as the first symptom. At the beginning of the disease, it usually starts to affect only one finger or one hand (usually the upper limbs), at rest and only at certain times of the day. As the disease progresses, it can begin to increase in duration and times of day when it manifests, as well as increase the areas affected by the tremor, which can affect muscles throughout the body and on both sides, such as the muscles of the face.
- Stiffness (characterized by stiffness or decreased flexibility in the limbs or joints) — Unlike tremors, muscle stiffness usually starts in the lower limbs or neck. Patients who present this symptom, the vast majority, feel their muscles tense and contracted, and may even feel pain. This rigidity affects and makes movement difficult.
- Bradykinesia or slowness of movement (characterized by the slow movement of the limbs or even the absence of them – Akinesia) — As the disease progresses, the patient begins to drag their movements, everything becomes very slow, almost in slow motion. The posture becomes stooped, walking is done slowly, often dragging the feet. It significantly reduces the patient’s mobility, making it difficult to perform simple everyday tasks such as eating or drinking, but also performing simple movements such as sitting. In the advanced stage of the disease, movement can even stop and the patient is bedridden and totally dependent on others to survive.
- Postural instability (characterized by loss of balance caused by tilting the posture) — as the patient begins to assume a stooped posture and with less muscle control, it becomes difficult to control balance (forward or backward), resulting in potentially dangerous falls.
The non-motor symptoms, that is, that are not related to the control of muscles and body movements, with higher prevalence are:
- sleep disturbances
- mood disorders
- partial loss of smell (hyposmia)
- gastrointestinal problems
- urinary dysfunctions
- memory loss
- changes in blood pressure
Another non-motor symptom related to Parkinson’s disease is the loss of cognitive abilities (dementia), which affects less than 50% of patients. However, it should be noted that this type of dementia is totally different from that observed in patients with Alzheimer’s disease. This dementia translates into a greater slowness of reasoning, in which patients think and respond more slowly, but they get the answers right.
Sometimes, certain symptoms such as sleep disturbances may appear far in advance of the onset of motor symptoms such as tremors.
There is currently no laboratory test to make a definitive diagnosis for Parkinson’s disease. This disease does not have a biological marker, so its diagnosis depends on the physician’s clinical evaluation, which is based on the patient’s clinical history (as well as family history), a neurological evaluation and the analysis of the results of some complementary diagnostic tests (such as CT scan or cranioencephalic MRI). Complementary diagnostic tests also allow screening and exclusion of other neurological diseases.
Once the neurologist is suspicious of the pathology in the face of his analysis, a trial of treatment with levodopa is usually carried out. That is, the doctor starts a treatment with a drug that is used in patients with the diagnosis already confirmed, observing if it promotes improvements in the patient’s condition. If these improvements occur, the probability of diagnosis confirmation increases.
Parkinson’s disease is a chronic neurodegenerative disease, that is, there is currently no cure for this disease. No drug or surgery has yet been developed to delay or prevent the progression of the disease.
There are, however, several therapeutic forms that seek to minimize the impacts caused by the symptoms of the disease, helping to improve the quality of life of patients with this pathology. Among the therapeutic forms applied, these can be:
- Drugs (as seen in confirmation of diagnosis using levodopa) — several classes of drugs can be used to treat the disease, such as dopominergic drugs (such as levodopa), which have a dopamine-like action on the system, MAO-B inhibitors that allow dopamine to degrade more slowly, among others that seek to improve or mimic the action of dopamine. Medications can also be used to relax the muscles.
- Surgical — the surgical option can be advised in more severe cases, through a Palidotomy (which results in the destruction of a specific region of the brain involved in the control of movement) or a Deep Brain Stimulation Therapy – DBS (a medical device is implanted in the brain that stimulates certain specific brain regions). DBS is reversible, unlike pallidotomy.
- Speech therapy
- Psychological support
- Nutritional support
Both treatments using drugs or surgery entail possible adverse side effects or collateral damage, sometimes intolerable and undesirable. For this reason, all therapies must be carefully analyzed by your doctor, in order to analyze their cost-benefit.
As we still do not know for sure the causes of Parkinson’s disease, it is not yet possible to define a concrete prevention strategy for it.
According to studies carried out over the years, the risk of developing Parkinson’s disease can possibly be reduced by practicing sports or aerobic physical exercise (walking, running, swimming, among others). Some studies suggest that consumption of caffeine, whether in coffee or tea, may also decrease the risk, but they are still inconclusive.