Measuring Parkinson’s: how long is a piece of string?
We delve into the challenges and rewards of measuring Parkinson’s, and why improving this is key to delivering better treatments.
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Over the past 20 years huge strides have been made in Parkinson’s research which are now leading to the development of new treatments with the potential to slow, stop or reverse Parkinson’s.
This is great news but there’s a catch. To deliver better treatments to people with the condition, we need to be able to prove their worth in numbers.
And that means finding ways to measure the progression of Parkinson’s accurately and meaningfully.
“Not everything that can be counted counts.
Not everything that counts can be counted.”
What can we learn from HIV?
Perhaps one of the most compelling examples of how improving the ability to measure an illness has accelerated improved treatments and care is in HIV and the ability to measure ‘viral load’.
Viral load is the term used to describe the amount of HIV in your blood. The more HIV there is in your blood (the higher your viral load), the faster your immune system will be damaged, and the greater your risk of becoming ill because of HIV.
In the 1990s, viral load tests were a new technology being developed as a research tool.
- in 1995 tests could measure down to 10,000 copies per millilitre of blood
- by 1996–7 tests could measure down to 400 or 500 copies/ml
- since 1998 most tests can measure down to 40 or 50 copies/ml
- and tests used in research are even more sensitive (down to 5 or even 1 copy/ml)
These rapid advances in the ability to measure viral load provided doctors and researchers with a direct way to measure the impact of each new drug. Before viral load tests, doctors were only able to measure the resulting impact on the immune system (by counting the number of remaining immune cells in the blood) or the development of symptoms.
Viral load tests are now a crucial part of treatment and care for people with HIV, and have played a vital role in improving life expectancy to near normal for those with the illness.
How we measure Parkinson’s today
The main way we measure Parkinson’s in clinical studies and trials today is using a scale called the Movement Disorders Society Unified Parkinson’s Disease Rating Scale (or MDS-UPDRS for short).
This assessment is composed of 50 questions about both movement (motor) and non-movement (non-motor) symptoms. Some parts are completed by the individual with Parkinson’s (sometimes with the assistance of their partner or carer) and other parts by a qualified clinician.
Each question is rated from 0 (normal) to 4 (severe), and then the marks are added up to give a total score which is intended to provide an overall indication of the severity of the condition.
There are also a range of other different scales and questionnaires that can be used in clinical trials to look at things like quality of life, activities of daily living and specific symptoms (such as memory or balance) in greater detail.
None are perfect and most studies will use a range of these tools to try and provide a picture of whether participants are improving or getting worse over time.
But while current methods for measuring Parkinson’s can be useful, there are some key challenges that mean we need to develop better methods.
Focused on symptoms
Current measures like the MDS-UPDRS primarily focus on the symptoms of Parkinson’s, and especially upon the movement-related symptoms like tremor, stiffness and slowness.
As a result, they can be very helpful for showing the benefits of therapies that ease symptoms — especially movement symptoms. But, they are less good at measuring the progression of Parkinson’s over time — which is crucial if we’re going to be able to demonstrate that a treatment can slow the course of the condition.
In the eye of the beholder…
Most of the current clinical measures and scales rely upon the judgement of either the clinician performing the assessment or the individual with Parkinson’s themselves. And this means they can be influenced by personal feelings, perceptions, or opinions.
For example, one of the questions in the MDS-UPDRS that participants answer is about handwriting:
This is actually a very difficult thing to judge objectively.
One person’s opinion and another’s on the same handwriting may vary hugely, so how meaningful can the scores really be?
A true picture of Parkinson’s?
Finally, one of the other challenges of the current clinical measures is that most of them are done in an ‘artificial’ environment — like a hospital — and can only capture a very brief snapshot of Parkinson’s.
For instance, if someone has to walk across a room while being filmed and watched by clinical professionals — does this meaningfully reflect their ability to walk around their home or to the shops?
Parkinson’s is a condition that can fluctuate considerably from day to day and even hour to hour. This means that one individual’s score could vary significantly depending on the time of day, whether they had a good nights sleep, their anxiety levels or if they have a cold. And this variability presents a particular problem when you’re trying to measure how someone’s condition is progressing over a relatively short period of time.
Creating better measures for Parkinson’s
This inability to objectively measure whether Parkinson’s is getting better or worse (or how quickly) is a major barrier in clinical trials that are testing new treatments that aim to slow, stop or reverse the condition.
The good news is that scientists across the world are working to find new and improved methods for measuring this complex condition, and exciting progress is being made.
Finding ‘biomarkers’
A biomarker is a measurable change in the body that can tell us something useful about the severity of an illness — like viral load in HIV, or blood-sugar levels for diabetes.
So far, we do not have any proven biological tests for Parkinson’s but thanks to the efforts of researchers, we have some very promising candidates being developed.
These include tests that analyse breath, blood and cerebrospinal fluid, and advances in brain imaging.
Harnessing technology
The development of new technologies also represent a huge opportunity to develop better ways to monitor Parkinson’s much more objectively.
Wearable technologies, like pedometers and wrist sensors, are being developed that can collect and analyse vast amounts of data around the clock to produce a much more meaningful and comprehensive picture of Parkinson’s symptoms.
Focusing on what matters
Finally and perhaps most importantly, if we’re going to develop treatments that meaningfully improve life for people with Parkinson’s, we need better ways to measure the real impact on everyday life.
One example of a new tool that aims to better capture this for Parkinson’s is the ‘Patient Reported Outcomes in Parkinson’s Disease’ (or PRO-PD) scale.
To get this right, people with the condition need to be involved in developing and testing all these new methods and scales to ensure they measure the right things and that they are practical to use in clinical trials.
Get involved
From shaping research to taking part in research studies to becoming a Research Volunteer, there is a role for anyone in the Parkinson’s community to get involved in research. And if you’re interested in finding out about these opportunities, or just want to stay connected with the latest research the Research Support Network is for you.
