Parkinson’s disease is a disorder that affects the brain. In healthy people, the thoughts, memory, emotions, touch, motor skills, vision, breathing, temperature, hunger and all the processes that regulate the body are controlled by the brain.
In people with Parkinson’s disease (PD), the part of the brain that produces a chemical (dopamine) required for voluntary and smooth movement becomes damaged or dies.
PD is a multifactorial disease and there could be several causes that could lead to disease development and damage to the brain cells (neurons). These causes could mainly be due to the body’s faulty mechanisms like the build-up or clearing of unwanted proteins, weakened function of the powerhouses of the cells (mitochondria), or chemicals released by the brain’s immune cells (microglial cells). Other causes may be genetic or coming into contact with harmful substances in the environment.
Not everyone with these symptoms will have PD, and not everyone with PD will experience all of these symptoms. They may be caused by other, more common conditions. But if you have any of the below-mentioned symptoms, it is important to get them checked by your doctor.
The most common symptoms of PD include:
The other wide range of physical and psychological symptoms that a person with PD can experience are as follows:
Involuntary functions like:
Changes in mood and thinking like:
Other physical changes like:
The reason why some people get PD is not completely understood. However, there are some factors that are known to increase the chance of a person developing this disease called ‘risk factors’. Having a risk factor does not mean that you will definitely get the disease, but the more risk factors you have can make it more likely. Some risk factors for PD are:
This happens when the disease is inherited due to the passage of faulty genes from parents to the child.
Men are twice as likely to have PD than women. Most people with PD start to develop symptoms when they are in their 60s, however, some people might first experience symptoms when they are under 40 or 50 years.
The mechanisms that cause PD are explained in detail below:
Since these mechanisms mainly happen in the parts of the brain that are responsible for physical movement, this is why people with PD experience symptoms affecting physical movement.
Greater understanding of what causes PD will help researchers find more effective ways to treat and manage it.
If your doctor thinks you might have PD, they will ask questions about symptoms, examine a certain part of the brain, refer you to a specialist (like a neurologist and/or a geriatrician), run certain mental or physical tests.
Symptoms of PD usually begin with early symptoms and the disease is known as ‘early/initial’ at this stage. PD may get worse over time. This is also known as ‘progressive disease’, or ‘disease progression’. As PD progresses, the symptoms become more severe from mid-stage to advanced-stage.
In 1967, Hoehn and Yahr defined five stages of PD based on clinical instability. This helped to classify PD into the early-stage represented by stages 1 and 2, the mid-stage represented by stages 2 and 3 and the advanced stage, represented by stages 4 and 5.
PD can be divided into three main stages:
Some doctors use a more complex scale to make sure that not only physical symptoms but all aspects of the disease are included in staging.
In rare cases, PD is caused by a change (known as 'mutation') in the genes that are passed on from parents. Some of the most common gene mutations a child can inherit from their parents are GBA, PRKN and PINK1.
People who are carriers of PD will not develop PD but may show milder or early symptoms of a condition called parkinsonism which describes several Parkinson’s-like symptoms like tremors, muscle rigidity and slowness of movement.
At the moment there is no cure for PD, so treatments are used to relieve symptoms in order to improve quality of life. The main treatments used for PD are:
Clinical trials (which can also be called ‘research studies’) are designed to look at how safe experimental drugs or procedures (such as new types of surgery) are and how well they work. Researchers are working hard to learn more about PD by researching on how to slow or halt the breakdown/death of brain cells (neurodegeneration) by enhancing the clearance of abnormal proteins and blocking their communication, improving mitochondrial activity and targeting the inflammation of neurons.
Furthermore, topics of research include immunotherapies, using established drugs for a new indication (drug repurposing), targeting a specific type of chemical messenger (neurotransmitter) system called non-dopaminergic neurotransmitter systems, components relating to the growth of nervous tissue called neurotrophic factors, regenerative treatments and advances in deep brain stimulation.
As researchers learn more about PD, clinical trials will be set up to look at potential new treatments.
If you would like to know more about Roche sponsored clinical trials or are interested in taking part in a clinical trial, speak to your doctor or visit the Roche ForPatients clinical trials page.
References
NHS. Parkinson’s disease. Overview. Accessed 16 January 2023. Available from: Link
John Hopkins Medicine. Brain anatomy and how the brain works. Accessed 16 January 2023. Available from: Link
National Institute of Neurological Disorders and Stroke. Parkinson’s Disease. What research is being done? Accessed 16 January 2023. Available from: Link
Poewe W, Seppi K, Tanner C.M, et al. Parkinson disease. Nat Rev Dis Primers. 2017 Mar 23; Volume(3):Article(17013). Available from: Link
NHS. Parkinson’s disease. Symptoms. Accessed 16 January 2023. Available from: Link
Michael J. Fox Foundation for Parkinson’s research. About Parkinson’s. Symptoms. Accessed 16 January 2023. Available from: Link
John Hopkins Medicine. How Parkinson’s disease is diagnosed. Accessed 17 January 2023. Available from: Link
Parkinson’s News Today. Types of Parkinson’s Disease. Accessed 17 January 2023. Available from: Link
NHS. Parkinson’s disease. Diagnosis. Accessed 16 January 2023. Available from: Link
American Parkinson Disease Association. What is a DaTscan and should I get one? Accessed 18 January 2023. Available from: Link
Parkinson's Europe. How is Parkinson’s diagnosed? Diagnosis. Accessed 17 January 2023. Available from: Link
NHS. CT scan. Accessed 18 January 2023. Available from: Link
NHS. MRI scan. Accessed 18 January 2023. Available from: Link
NHS. PET scan. Accessed 18 January 2023. Available from: Link
Parkinson's Foundation. Stages of Parkinson’s. Accessed 17 January 2023. Available from: Link
International Parkinson and Movement Disorder Society. MDS-UPDRS. The MDS-sponsored Revision of the Unified Parkinson’s Disease Rating Scale. Accessed 23 January 2023. Available from: Link
Parkinson's Foundation. Understanding genetics. Accessed 17 January 2023. Available from: Link
NHS. Parkinson’s disease. Treatment. Accessed 16 January 2023. Available from: Link
Thomas B. Stoker and Roger A. Barker. Recent developments in the treatment of Parkinson’s Disease. F1000Res. 2020 July 31;9:F1000 Faculty Rev-862. Available from: Link
Skowronek C, Zange L and Lipp A. Cardiac 123I-MIBG Scintigraphy in Neurodegenerative Parkinson Syndromes: Performance and Pitfalls in Clinical Practice. Front Neurol. 2019 Feb 26; Volume(10):152. Available from: Link