Understanding Parkinson

April 11 is World Parkinson's Day. This day of action is intended to draw attention to the disease itself and its impact on the lives of sufferers and their families, as well as to progress in treatment. The date is not arbitrarily chosen, but coincides with the birthday of the English physician James Parkinson, who first described the disease in 1817.

But what is Parkinson's disease anyway? How does the disease develop and what phases do patients go through? What are typical symptoms and how is Parkinson's diagnosed?

What is Parkinson's disease?

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's dementia. This means that the disease affects the nerve cells of affected individuals. To date, Parkinson's disease cannot be cured, 1,2 but it can be treated well. According to the European Parkinson’s Disease Association (EPDA), around 10 million people have the condition worldwide, with men developing the disease somewhat more frequently than women.3 On average, Parkinson's disease appears in patients at the age of 60, although in some patients the first symptoms appear before the age of 40, and in rare cases the disease can also break out in adolescence (juvenile Parkinson's syndrome)3,4.

Parkinson's disease is caused by a gradual degeneration of certain nerve cells in the brain

How Parkinson's disease develops is not yet fully understood. Only a few cases can be attributed to a hereditary predisposition. Previous damage to the brain due to severe head injuries, strokes or tumors can increase the likelihood of Parkinson's. In most cases, however, no cause can be identified and the disease is referred to as idiopathic (i.e., "without an identifiable cause") Parkinson's syndrome.

Sleep disturbances and depression can also be early signs of Parkinson's and can occur years before the actual onset of the disease.

In people with Parkinson's disease, nerve cells in the brain that produce the neurotransmitter dopamine die at a greatly increased rate. These nerve cells are located in an area of the brain called the substantia nigra ("black matter"), which is responsible for voluntary movement and coordination. The death of the nerve cells and the resulting lack of dopamine lead to impaired signal transmission in the brain. This increasingly leads to a loss of control over voluntary and involuntary movements as well as other typical symptoms such as muscle tremor, muscle stiffness (rigor), lack of stability in the upright posture (postural instability) and slowing of movement (bradykinesis). This process is gradual and the death of dopamine-producing neurons usually begins long before the first symptoms appear.

Typical symptoms of Parkinson's disease

Parkinson's usually starts slowly and with non-specific symptoms. Patients often describe that they fall more frequently and report the first loss of control of motor functions. This manifests itself, for example, in drooping arms and an altered gait due to dragging of the legs. Sleep disturbances, reduced bowel activity leading to constipation or disturbances in the sense of smell are further initial signs. Calf cramps, and pain in the back, shoulders or arms can also be early symptoms. Some patients also suffer from depression.

In most cases, other complaints are added in the course of time. Various main symptoms can occur:

• Bradykinesis (slowing of movement)/ akinesia (lack of movement):
There are four main symptoms. One of them is bradykinesia - an increasing slowing of movements, which often also manifests itself in reduced mimic movement and speech disorders. Patients can only move around with great difficulty, their steps become smaller and they develop the typical bent-over, small-stepped and shuffling gait.

• Rest tremor:
A tremor at rest is the most noticeable symptom. When the patient is at rest, it is mainly the head and hands that tremble. With movement, the tremor decreases or disappears completely.

• Rigor:
This main symptom of Parkinson's disease is understood to be a persistent and involuntary muscle tension (also known as increased muscle tone). This mainly affects the flexor muscles, resulting in the typical bent-forward posture with bent arms. If, for example, the elbow or wrist of an affected person is passively flexed and extended, the so-called "cogwheel phenomenon" can occasionally be triggered - the movement is then not made in one go, but in several small steps.

• Postural instability (stance and gait insecurities, tendency to fall):
Damage to dopamine-producing nerve cells makes it difficult for some Parkinson's patients to maintain an upright posture. Position and posture reflexes, which subconsciously regulate gait and balance, can lose their functionality. This can cause difficulty with movements. In addition, patients may be prone to falls and stumbles.

Sleep disturbances and depression can also be early signs of Parkinson's and can occur years before the actual onset of the disease.

Over time, behavioral changes may also become noticeable. Parkinson's patients may generally react more irritably, gradually withdraw and avoid social contacts. This can be attributed primarily to deterioration in speech and writing, as well as other general limitations. For this reason, it is particularly important that patients receive appropriate therapy in order to maintain as much flexibility as possible in everyday life and continue to lead a self-determined life.

How is Parkinson's diagnosed?

Currently, there is no standardized diagnostic procedure for the detection of Parkinson's disease. The course of the disease is very individual, and early symptoms can be very nonspecific. If patients or relatives notice changes, the doctor first tries to find out the time of the first onset and the type and duration of the symptoms. Further diagnostic options, such as computed tomography (CT) or magnetic resonance imaging (MRI), can be consulted to rule out other triggers such as tumors or strokes. Ultimately, the exclusion of other diseases in combination with the occurrence of one or more main symptoms leads to the diagnosis of PD.

Parkinson's disease is very treatable today. For patients at every stage of the disease, there are therapeutic options in the form of medicines or technical aids that can support the self-determination and freedom of the person affected. Unfortunately, Parkinson's is often only diagnosed at an advanced stage - not least because of the often initially unspecific symptoms. The unfortunate fact is that the later the diagnosis is made, the more advanced the restrictions in the patient's life usually already are. If the disease is diagnosed early, the right treatment can "freeze", i.e. maintain, the existing status quo of the patient's mobility and thus flexibility for a longer period of time.

Sources:

1. Dorsey ER, Elbaz A, Nichols E, et al. Global, regional, and national burden of Parkinson’s disease, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet Neurol 2018;17(11):939–53.

2. Nussbaum RL, Ellis CE. Alzheimer’s Disease and Parkinson’s Disease. N Engl J Med 2003;348(14):1356–64.

3. Heinzel S, Berg D, Binder S, et al. Do We Need to Rethink the Epidemiology and Healthcare Utilization of Parkinson’s Disease in Germany? Front Neurol 2018;9:500.

4. Deutsche Gesellschaft für Klinische Neurologie und Funktionelle Bildgebung (DGKN). Morbus Parkinson. Online: https://dgkn.de/neurophysiologie/der-ueberblick/morbus-parkinson. As of 19 March 2021.