Current DateSeptember 24, 2021

Parkinson’s disease: causes, symptoms & treatment

Parkinson’s disease is a disease of the nervous system that affects movement. It develops gradually, sometimes starting with a barely noticeable tremor in one hand. It also causes stiffness or the slowing down of movement.

Parkinson’s disease is a degenerative disease that results from the slow and progressive death of neurons in the brain. Since the area of ​​the brain affected by the disease plays an important role in controlling our movements, people with the disease gradually make rigid, jerky and uncontrollable gestures. For example, bringing a cup to one’s lips with precision and flexibility becomes difficult. Nowadays, the treatments available can reduce the symptoms and slow the progression of the disease quite effectively. You can live with Parkinson’s for several years.

Parkinson’s-related disorders most often appear around the age of 50 to 70. The average age of onset of the disease in the United States is 60 years, according to the National Institute on Aging. At first, the symptoms may be mistaken for a person’s normal aging, but as they get worse the diagnosis becomes more obvious. By the time the first symptoms appear, it is estimated that 60% to 80% of the nerve cells of the substantia nigra have already been destroyed. Thus, when symptoms appear, the disease already has an average of 5 to 10 years.

In the United States, the disease is diagnosed in more than 60,000 people each year. The number of cases increases with age. It is estimated that at 65, one in 100 people will be affected, and 2 in 100 people will be affected by the age of 70 and over.

At the heart of the disease: a dopamine imbalance

The nerve cells affected by Parkinson’s disease are located in an area called “substantia nigra”, which itself is located in the midbrain. Cells in this area produce dopamine, a chemical messenger (called a neurotransmitter) which controls movement but also acts on the sensation of pleasure and desire.

The death of substantia nigra cells creates a lack of dopamine, leading to an increase in acetylcholine and glutamate (two other chemical messengers). This imbalance causes the symptoms of the disease to appear, namely tremors, muscle stiffness and inability to perform certain movements. Conversely, an excess of dopamine could be the cause of symptoms associated with schizophrenia.

Causes Parkinson’s disease

What causes the progressive loss of neurons in Parkinson’s disease remains unknown in most cases. Scientists agree that a set of genetic and environmental factors are involved, without always being able to define them clearly. According to the current consensus, the environment plays a more important role than heredity but genetic factors are predominant when the disease appears before the age of 50 years. Here are some environmental factors involved:

  • Early or prolonged exposure to chemical pollutants or pesticides, including herbicides and insecticides;
  • MPTP, a drug that sometimes contaminates heroin, can suddenly cause a severe and irreversible form of Parkinson’s. This drug exerts its effect similarly to the pesticide rotenone;
  • Carbon monoxide or manganese poisoning.

The researchers also noted that many changes occur in the brains of people with Parkinson’s disease, although the reasons for these changes are not established. These changes include:

  • The presence of Lewy bodies, which are substances found in brain cells (neurons). Researchers believe that these Lewy bodies play a toxic role in Parkinson’s disease.
  • The presence of alpha-synuclein in Lewy bodies. Although many substances are present in Lewy bodies, scientists believe that alpha-synuclein is a protein that plays a harmful role when it is in an aggregated form that cannot be dissolved by cells.

Evolution and possible complications

The progression of Parkinson’s disease varies among individuals. Parkinson’s disease is chronic and progresses slowly, which means the symptoms get worse over several years.

  • Motor symptoms vary from person to person, as does their progression.
  • Some of these symptoms are more inhibiting than others depending on what a person does normally during the day.
  • Some people with Parkinson’s disease live with less disabling symptoms for many years, while others develop motor difficulties more quickly.
  • Non-motor symptoms also vary from person to person and affect most people with Parkinson’s disease, regardless of the stage of the disease. Some people with the disease find that symptoms such as depression or fatigue interfere with their daily activities more than motor problems.
  • Parkinson’s disease is often accompanied by the following problems which may be treatable:
  • Difficulties in thinking. The onset of cognitive impairment usually occurs in the later stages of the disease. Such cognitive problems do not respond very well to medication.
  • Mood disorders. People with Parkinson’s disease can suffer from depression. By having treatment for depression, it is easier to manage the other problems of Parkinson’s disease. Other disorders such as anxiety or loss of motivation can accompany depression.
  • Swallowing problems. The person has difficulty swallowing as their condition worsens. Saliva can build up in the mouth due to slow swallowing.
  • Sleeping troubles. People with Parkinson’s disease often have trouble sleeping (Insomnia). They wake up frequently at night, wake up early, or fall asleep during the day.
  • Incontinence. Parkinson’s disease can cause bladder problems, resulting in an inability to control urine or difficulty passing urine.
  • Constipation. Many people with the disease become constipated, mainly due to a slower digestive tract.
  • Change in blood pressure, with dizziness or lightheadedness (orthostatic hypotension).
  • Odor disorders. Difficulty identifying or differentiating certain smells.
  • Tiredness. Many patients experience fatigue, and the cause is not always known.
  • Pain. Many people with the disease experience pain, either in specific areas of the body or throughout the body.
  • Sexual dysfunction. Some people with the condition report a decrease in sexual desire or performance.

Symptoms of Parkinson’s disease

Symptoms related to motor skills often appear asymmetrically, that is, reaching only one side of the body, then spreading to both sides of the body after a few years

In 70% of cases, the first symptom is uncontrollable rhythmic tremors of one hand, then of the head and legs, most notably at rest or during times of stress. On the other hand, 25% of patients do not present any tremor.

N.B. The tremor that occurs on action, for example when lifting an object, is not a sign of Parkinson’s.

  • A decrease and cessation of tremors when the person is moving and when sleeping;
  • The stiffness of the limbs, slow movements (bradykinesia), rigid and jerky, difficult to initiate. As the disease progresses, it can make it difficult to perform daily tasks such as buttoning clothes, tying shoelaces, picking up coins, walking, standing or getting out of a car;
  • The parkinsonian gait: small steps shuffling of the feet, the hunched back, with little or no swing of the arms;
  • Loss of smell, sleep disturbances, constipation, which may appear early;
  • Loss of balance, occurring later in the course of the disease.

Parkinsonian gait demonstration

Credit: prohealthsys/Youtube

Other symptoms that may accompany Parkinson’s disease:

  • Depression and anxiety;
  • Difficulty swallowing;
  • Excessive salivation with difficulty in containing saliva (the person drools);
  • A small, very tight handwriting (micrograph), due to loss of dexterity;
  • A quavering voice, expressionless and difficult to articulate;
  • A lack of facial expression, with a decrease or absence of fluttering of the eyelids;
  • The presence of dandruff and oily skin on the face;
  • Urinary incontinence;
  • Confusion, memory loss and other fairly significant mental disorders, occurring rather late in the course of the disease;
  • Difficult changes of position; it may be difficult to get out of bed or a chair, for example. And in some cases, it becomes impossible to move.

Parkinson’s syndrome or Parkinson’s disease?

Symptoms similar to Parkinson’s disease may appear in some people, but cannot be diagnosed as Parkinson’s. In fact, Parkinson’s disease accounts for 85% of cases in a group of diseases known as “parkinsonian syndrome”. The latter is also manifested by movement disorders but the physiology of the disease differs. This is because parkinsonism is usually caused by an imbalance in the cholinergic system (acetylcholine) rather than by a lack of dopamine. Overall, some differences are visible and the treatment is not the same.

Some conditions that can trigger Parkinson’s syndrome include damage to the brain as a result of trauma or tumor, minor strokes, and the consumption of certain drugs used to treat nausea, epilepsy, hypertension or psychiatric disorders. Various infrequent neurological diseases are also manifested by parkinsonism.

Diagnostic

There is no specific test to diagnose Parkinson’s disease. The neurologist will diagnose the condition based on the person’s medical history, an examination of signs and symptoms, and a neurological exam.

The doctor may order tests, such as blood tests, to rule out other conditions that may be causing these symptoms.

Imaging tests – such as an MRI or a brain scan – can also be used to help rule out other disorders. Imaging tests are not particularly useful for diagnosing Parkinson’s disease.

In addition to a standard test, your doctor may give the person carbidopa-levodopa, a medicine used to treat Parkinson’s disease. The patient will be given a dose sufficient to see benefits from the drug, as low doses given for a day or two are not sufficient. Significant improvement with this medication will often confirm a diagnosis of Parkinson’s disease.

Diagnosis of Parkinson’s disease can take a long time. Doctors may recommend regular follow-ups to assess the person’s condition and symptoms over time.

People at risk

  • The disease more often affects people aged 55 and over;
  • Men are more often affected than women for reasons that are not yet known;
  • A person with a parent who has the disease has a higher risk of developing the disease themselves. But the genetic contribution would be especially important in those who develop the disease when they are young.

Risk factors

People with Parkinson’s disease often experience periods of depression. However, researchers are now studying the hypothesis that depression is a predisposing factor to the disease. However, this remains to be demonstrated. In some people it may be just an early manifestation of the disease.

Prevention of Parkinson’s disease

There is no recognized way by doctors to prevent Parkinson’s disease. However, here’s what research shows.

  • Caffeine consumption

Men who consume moderate caffeinated drinks (coffee, tea, cola) (1 to 4 cups per day) may benefit from a protective effect against Parkinson’s disease, according to some cohort studies.

A study carried out on a population of Chinese origin showed the same effect. On the other hand, in women, the protective effect has not been demonstrated as clearly.

Furthermore, an 18-year cohort study found that the risk of Parkinson’s disease decreased in coffee users who did not take hormone replacement therapy during menopause. Conversely, taking hormone replacement therapy and caffeine together would increase the risk.

  • Consumption of green tea

Drinking one to four cups of green tea a day also appears to prevent Parkinson’s disease, an effect believed to be due, at least in part, to the presence of caffeine in green tea. For men, the most effective doses range from around 400 mg to 2.5 g of caffeine per day, or a minimum of 5 cups of green tea per day.

  • Smoking (not recommended)

In addition, people addicted to tobacco are less likely to have Parkinson’s disease. According to a meta-analysis published in 2012, the risk of getting Parkinson’s disease is reduced by 56% in smokers, compared to those who have never smoked. Nicotine would stimulate the release of dopamine, thus compensating for the dopamine deficit found in patients. However, this benefit does not weigh heavily in comparison with all the diseases that smoking can cause, in particular several types of cancer.

  • Taking ibuprofen

Several meta-analyzes indicate that ibuprofen may be associated with a reduced risk of Parkinson’s disease. Data on other nonsteroidal anti-inflammatory drugs (NSAIDs) are conflicting, with some meta-analyzes finding that NSAIDs are associated with a reduced risk of disease while others report no significant association.

It is important to remember that these prevention techniques are only hypothetical. Their validity remains to be proven. Furthermore, experts highly discourage patients from engaging in smoking as it has been proven on countless studies that it causes more harms than good.

Medical treatments for Parkinson’s disease

While there are no treatments that can cure Parkinson’s disease, it is nevertheless possible to alleviate the symptoms through the use of drugs but also by following certain lifestyle measures. Usually, the symptoms are controlled quite successfully if the treatment is well adjusted according to the course of the disease. Despite the anxiety and discouragement that the disease can engender, having an active role in its management allows you to live better with the decisions that have been made.

  • Stay active

It is very important that the patient remains active and that they exercise regularly. Regular physical activity increases the body’s mobility, balance, and coordination, and helps fight depression. The doctor may suggest a specific exercise program, but any form of physical activity (walking, swimming, gardening, etc.) is beneficial.

In addition, since people with Parkinson’s disease are more prone to osteoporosis, it is advisable to practice weight-bearing joint exercises to strengthen the skeleton (lifting weights, walking, jogging, jumping in place, etc.) . Still in the same context, it is also necessary to take a small regular “dose” of sun to counter a possible lack of vitamin D, a frequent deficiency in the case of Parkinson’s disease. Vitamin D plays an essential role in bone health.

  • Allow yourself periods of relaxation

Practicing a relaxation technique, such as yoga or tai chi, or using massage therapy is important for reducing stress. In people with Parkinson’s disease, stress increases the intensity of the tremors.

  • Prevent falls

The more the disease progresses, the more difficult it becomes to walk. It is therefore important to get good shoes – avoid slippery soles – and practice taking long strides by lifting your legs high. Walking training by a physiotherapist is often recommended. To minimize the risk of falls, the patient’s space should be properly arranged. For example, it is better to remove rugs, install grab bars near the toilet and bathtub, and handrails on the stairs. An occupational therapy assessment is often necessary.

  • Nutrition

In order to increase the beneficial effect of the prescribed medication, the doctor may make certain dietary recommendations. Consuming the majority of protein at the evening meal and maintaining a carbohydrate-to-protein ratio of 7 to 1 (7 g of carbohydrate to 1 g of protein), for example, is a favorable measure.

According to Mayo Clinic, it is recommended that you eat a diet rich in fruits, vegetables and whole grains, which provide natural antioxidants that protect against oxidative damage. These foods are also a good source of dietary fiber, which promotes better intestinal transit. Consumption of saturated fat (red meats, dairy products, palm and coconut oil, etc.) should be reduced19.

At an advanced stage of the disease, chewing becomes difficult: it is important to take small bites. To facilitate swallowing, more substantial foods can be passed through a blender before consumption.

In order to prevent constipation associated with Parkinson’s disease, doctors recommend drinking at least 1 liter of water per day and getting enough dietary fiber.

  • Social support

Recourse to a resource person (a psychologist, a psychotherapist, etc.) is often useful, even necessary, to face the ordeal of any chronic illness. Parkinson’s disease can be particularly difficult to deal with since it attacks the biochemistry of the brain – which is often a major source of anxiety. You can also join a support group.

  • Medication

The appropriate time to start medication depends on several factors (age, lifestyle, severity of symptoms, hobbies, etc.) and will be determined in consultation with a physician. The drugs prescribed are aimed at reducing the symptoms of the disease, but do not stop its progress. Finding the ideal treatment can take time; it is recommended that you report any new symptoms that appear during treatment to your doctor to make the necessary adjustments.

  • Levodopa, or L-dopa, is a precursor to dopamine. In the brain, levodopa is converted into dopamine. It is often prescribed in conjunction with carbidopa or benserazide in order to increase the effects or limit the side effects (nausea, vomiting, dizziness upon awakening). Levodopa is particularly effective in easing movement difficulties, tremors and stiffness in the limbs. As the effectiveness of levodopa wanes over time – it often becomes much less effective after 5 or 6 years – doctors usually wait until symptoms of the disease are significant before prescribing it.
  • Dopamine agonists mimic the effects of dopamine (examples are bromocriptine, pergolide, pramipexole, and ropinirole). These drugs can be prescribed as soon as the diagnosis is made and can be combined with levodopa when the disease is at an advanced stage. These drugs have side effects similar to levodopa, but they can also cause compulsive behaviors (compulsive gambling, hypersexuality, compulsive shopping), in 7 to 13% of cases according to some studies.
  • Monoamine oxidase B (MAOB) inhibitors, such as selegiline and rasagiline, may be prescribed early in the disease. They decrease the degradation of natural dopamine as well as the one formed from levodopa. In addition, they would prevent the formation of free radicals and neurological toxins, thus protecting healthy cells. This protective effect has not been fully demonstrated. This class of drugs sometimes causes side effects, such as tremors and confusion. It has many interactions with other drugs and natural health products.
  • Anticholinergics (benzotropine, trihexyphenidyl) help reduce tremors in some people by restoring the balance between dopamine and acetylcholine in the brain. It is usually prescribed for younger patients in whom tremors are the dominant symptom. This is the oldest type of drug available to patients.
  • Catechol O-methyltransferase (COMT) inhibitors prolong the effect of carbidopa-levodopa treatment by blocking the enzyme that breaks down levodopa. Tolcapone is only prescribed for people who do not respond to other therapies because it can lead to liver damage. Entacapone (Comtan) does not cause this problem. However, it can make the side effects of levodopa worse.
  • Amantadine, an antiviral drug initially developed to treat influenza, has shown beneficial effects for people with Parkinson’s disease. As this medicine only slightly reduces symptoms, it is used in patients who have an early stage of the disease. Its mechanism of action in the brain is not yet well known. When combined with levodopa, amantadine can help reduce motor problems in the later stages of the disease.

Note. Levodopa and dopamine agonists can cause drowsiness during the day. Vigilance is required since some patients treated with these drugs may experience drowsiness during dangerous activities, for example, while driving.

In addition to drugs used to reduce movement disorders, an antidepressant is sometimes prescribed. Several factors can lead to a depressive state in the patient: having to live with a chronic degenerative disease, the difficulty of performing certain tasks, the physiological changes that take place in the brain during the disease and the side effects of certain medications.

  • Surgery

For patients with an advanced stage of the disease, whose symptoms no longer respond stably to levodopa, brain surgery may be considered.

Deep brain stimulation involves the implantation of electrodes in specific parts of the brain (the thalamus, pallidum or subthalamus). A stimulator then sends electrical impulses to reduce involuntary movements and tremors. However, this procedure does not reduce muscle rigidity, does not correct the loss of voluntary movement and would involve certain risks of serious side effects.

In the past, small lesions were performed in the portion of the brain responsible for Parkinson’s symptoms: pallidotomy (pallidum), thalamotomy (thalamus) or sub-thalamotomy (subthalamic nucleus). These very delicate brain surgeries are very rarely used today.

  • Physiotherapy and speech therapy

Physiotherapy which includes daily physical exercise, gymnastics, gait training, postural balance work, etc. is an important therapeutic supplement. Occupational therapy is indicated for functional rehabilitation and home adaptation. Speech therapy is used in the management of dysarthria, a language expression disorder.

  • Experimental treatments

Various innovative treatments, such as fetal dopaminergic cell transplants and gene therapy, are being explored, but these are experimental treatments, none of which are commonly practiced.

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