Don’t young people get Parkinson’s disease?

Author: Chen Haibo, chief physician of Beijing Hospital

Reviewer: Xu Jun, Chief Physician, Beijing Tiantan Hospital, Capital Medical University

When people think of Parkinson's disease, they usually think of the elderly and believe that young people will not get Parkinson's disease. Is this really the case?

1. Will young people get Parkinson’s disease?

Parkinson's disease is divided into two categories: early-onset and late-onset. Onset after the age of 50 is generally called late-onset. Onset between the ages of 21 and 50 is called young-onset. Onset before the age of 21 is called juvenile-onset. Young-onset and juvenile-onset are collectively referred to as early-onset.

In fact, early-onset Parkinson's disease is relatively rare in general. In 2017, among the 121 rare diseases announced by our country, early-onset Parkinson's disease was one of them.

Generally speaking, among all Parkinson's disease patients, the proportion of early-onset patients accounts for about 10%. In some European and American countries, the incidence of early-onset Parkinson's disease is even lower. There are reports that it accounts for about 5%, and there have been reports in Japan that it accounts for about 10%.

There was a literature report in our country that counted more than 940 consecutive Parkinson's disease patients in outpatient clinics. Among these 940 cases, 9.1% developed the disease before the age of 40. So this data is basically similar to the international data, that is, between 5% and 10%, which is relatively small overall.

So overall, young people and teenagers can also get Parkinson's disease, but it is relatively less common and rare.

2. What is the main cause of juvenile Parkinson's disease?

There are many causes of Parkinson's disease. The first is related to aging. The older you are, the higher the incidence rate. The same is true for juvenile Parkinson's disease. The older you are, the higher the incidence rate of Parkinson's disease. For example, compared with a 20-year-old, a 30-year-old is more likely to get Parkinson's disease.

The second is environmental factors, which may be a relatively important and dominant factor among middle-aged and elderly people with Parkinson's disease, that is, among patients with late-onset Parkinson's disease.

For patients with juvenile Parkinson's disease, genetic factors play a more important role. More than half of adolescent patients, especially those with juvenile Parkinson's disease before the age of 20, often have related pathogenic genes.

This suggests that genetics plays a greater role in the development of juvenile Parkinson's disease.

Figure 1 Original copyright image, no permission to reprint

At present, more than 20 genetic genes that are clearly related to Parkinson's disease have been found. Some are pathogenic genes, and some are susceptibility genes. Different pathogenic genes have different pathogenicity.

3. What tests are generally needed to diagnose Parkinson’s disease?

All patients diagnosed with Parkinson's disease must have the so-called Parkinson's disease symptoms. Only when they have the symptoms can we consider that they have Parkinson's disease. As for other symptoms, although those symptoms are also part of the manifestation of Parkinson's disease, they are not as characteristic. So we still rely on these to diagnose Parkinson's disease, and this requires face-to-face examination by a doctor.

Some patients may not be so typical. If his symptoms are atypical, we need to do some tests to identify him. For example, we can do some ultrasound called substantia nigra. Substantia nigra ultrasound is ultrasound that hits the substantia nigra in the brain.

The substantia nigra is a key site for Parkinson's disease. We call it the location of dopamine neurons. In this area, there is an increase in the deposition of some metals, especially iron, which may be related to the development of our disease. When iron deposition increases, high echoes can be seen when ultrasound is used.

Generally speaking, most Parkinson's disease patients have ultrasound echoes above level three, which we divide into levels one, two, three, four, and five. Level three and above have relatively strong echoes. Of course, although the probability of level four is relatively low, it is more specific. So this may increase, which can also help us diagnose.

There are also some other tests, such as obvious tremor, high muscle tension, and decreased dopamine nerve cells, which can assist in the diagnosis of Parkinson's disease. Of course, generally speaking, imaging examinations of the head, such as CT, MRI, etc., are routine examinations that must be done.

4. Which medications are likely to induce Parkinson's disease-like symptoms?

There are many drugs that can induce Parkinson's-like symptoms. Generally speaking, if it is induced by drugs or toxic substances, we call it secondary. In other words, its cause is external and clear.

Drug-induced Parkinson's disease can occur in both juvenile and late-onset forms.

The most common ones are antipsychotic drugs. Some adolescents have mental disorders and need to use some antipsychotic drugs. However, many antipsychotic drugs are anti-dopamine. In other words, the mechanism of action of these drugs is somewhat similar to the pathogenesis of Parkinson's disease. Parkinson's disease is caused by a decrease in dopamine in the body, but too much dopamine will easily cause mental symptoms, so he must use some drugs to control mental symptoms.

Figure 2 Original copyright image, no permission to reprint

However, while controlling the symptoms of Parkinson's disease, the excitability of the dopaminergic system will also be reduced, resulting in symptoms similar to Parkinson's disease. This situation is sometimes collectively referred to as extrapyramidal complications or side effects, and can also be called drug-induced Parkinson's syndrome.

In addition, some drugs used to treat internal diseases can also easily cause Parkinson's-like symptoms. For example, a drug currently used to treat migraines and dizziness, called flunarizine, and cinnarizine, can also easily cause Parkinson's-like symptoms.

There is such a patient in the clinic. He had a stroke due to many factors of cerebrovascular disease. After the stroke, he often felt dizzy and had headaches. The doctor gave him flunarizine and told the patient that this drug improves circulation and that he had to take this drug because he had a stroke.

Then the patient started taking the drug. After two or three months, he began to experience symmetrical limb tremors, and then slowly, his legs seemed to be unable to move. Later, he went to the hospital for treatment. Upon inquiry, he was found to have taken flunarizine for almost half a year. After stopping the drug quickly, after two weeks, the symptoms improved significantly. This is drug-induced Parkinson's syndrome.

Therefore, flunarizine is a commonly used drug for the treatment of dizziness, headache, and even cerebrovascular disease. However, continuous use should not exceed 2 months. Long-term use can easily lead to Parkinson's disease-like symptoms, so if you experience any discomfort during use, you should seek medical attention at any time.

Now we have also found that many other drugs can also cause Parkinson's disease-like symptoms. For example, the antiemetic drug metoclopramide and the antihypertensive drug reserpine tablets can also easily induce Parkinson's disease-like symptoms.

Therefore, whether Parkinson's disease-like symptoms appear for unknown reasons or related symptoms appear while taking certain medications, you should see a doctor at any time and receive targeted examinations, diagnosis and treatment under the guidance of a doctor to avoid delays in the disease.

5. What are the drugs for treating juvenile Parkinson’s disease?

Currently, the drugs used to treat Parkinson's symptoms are exactly the same as those used to treat late-onset Parkinson's disease. There are six main types of drugs:

The first category is levodopa preparations, which are the first choice drugs for treating Parkinson's disease.

The second type is dopamine receptor agonist. This agonist is a dopamine mimetic. It is similar to dopamine in structure, so it can play a similar role as dopamine.

The third category is monoamine oxidase B inhibitors. This drug can reduce the degradation of levodopa in the peripheral blood, so that more levodopa can enter the brain. After it turns into dopamine in the brain, it can also inhibit the enzyme that degrades dopamine, which will increase the dopamine in the brain. Therefore, the increase of dopamine in the brain, whether it is dopamine entering from the outside or inside the brain, can improve the symptoms of Parkinson's disease.

There is another class of drugs called catechol-O-methyltransferase inhibitors. For example, entacapone. It is also an inhibitor of the degradation enzyme of levodopa. This inhibitor can only work in the peripheral blood and cannot enter the brain. Therefore, it allows more levodopa to enter the brain and also plays a role in increasing the concentration of dopamine in the brain. In fact, it is an auxiliary role and must be used in combination with levodopa to be effective.

The fifth type is called amantadine, which can promote the release of dopamine, has some neuroprotective effects, and also has some anticholinergic effects.

The sixth category of drugs is called anticholinergic drugs. The most typical anticholinergic drug is called trihexyphenidyl, which has a good effect on the tremor of Parkinson's disease. However, it is not so effective for rigidity and immobility, so for patients with tremor characteristics, trihexyphenidyl drugs are still effective.

Of course, Parkinson's patients may have many other symptoms, and there are many drugs to choose from. Only by choosing medication under the guidance of a clinician can a better treatment effect be achieved.