Making an impact in Parkinson’s research
How do researchers get to the top of their field? And what recent findings have made the biggest impact? We discuss how impact is measured, and what this means for Parkinson’s research.
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How do we measure the impact of new research findings?
At Parkinson’s UK, we fund research towards a cure, as well as projects that aim to improve life for people with Parkinson’s. And it is important to know the researchers and results that are making waves in the Parkinson’s field.
When researchers have new findings, they share their results with each other through scientific articles. You can read about this in a previous blog post:
Quality, high impact research articles are often referred to and mentioned in future researchers work as they build upon the original finding. These mentions are called ‘citations’ — each time the original article is mentioned it is ‘cited’. A high number of citations show that the original finding is being used by other researchers to inform their work and is likely to be an important finding.
For example, let’s take a look at some genetic research in Parkinson’s. Genes are important as they contain the instructions needed to make proteins — the building blocks of our cells — and changes in certain genes, such as LRRK2 and GBA are linked to Parkinson’s. In February 2016, Professor Richard Wade-Martins and colleagues at the University of Oxford wrote an article that described how changes in the GBA gene can alter the waste-disposal system in cells. A few months later, Professor Anthony Schapira and other researchers at University College London cited Richard’s original article in their new paper, further investigating the proteins that misbehave in the waste disposal system.
Measuring citations to measure impact
We can count the number of times an article is mentioned to get a total number of citations. Richard’s paper from 2016 has now been cited over 35 times. The number of citations is a rough measure of the impact of the article.
Each article from Parkinson’s UK funded research is cited an average of 18 times. This indicates that our findings are being well utilised by the research community to drive our understanding of Parkinson’s forward.
If we use this measure we can identify the highest impact paper from a Parkinson’s UK project. This accolade goes to Ruth Lovering and colleagues who created a resource of over 850 genes and associated proteins, and the role they play in Parkinson’s. Each protein in the database also has a score which indicates how much is currently known about it. The team have made this resource available online so other researchers can easily access and benefit from their findings. Their article that described, the Universal Protein resource (UniProt), has been cited over 900 times! One of the reasons this article has been cited so often is the resource contains information about genes and proteins not just from Parkinson’s, but from many other conditions too.
How do researchers make a name for themselves?
Researchers build a reputation by getting grants, publishing articles and having these articles cited by others. Parkinson’s UK has funded many researchers who are well known for their high impact research.
Professor John Hardy at University College London was awarded a grant in 2009 to find out which genes make people more likely to develop Parkinson’s. His work has helped researchers understand more about how our genes are responsible for altering the levels of different proteins in the brain cells affected by Parkinson’s. John has contributed to hundreds of papers on the genetics of Parkinson’s, and some have been cited over 200 times.
Before joining the Parkinson’s UK Research team as the Deputy Director for Research, Prof David Dexter worked as a researcher for 32 years. Many of his citations stem from his work on iron accumulation in the brains of people with Parkinson’s, and his role as the scientific director of the Parkinson’s UK tissue bank. David has contributed to hundreds of articles on Parkinson’s and amassed thousands of citations to his work.
When I started my PhD, amazingly very little was known about what was causing the neurons to die in Parkinson’s. My research sparked a new wave of discovery, which showed for the first time that brain cell loss in Parkinson’s is linked to the build-up of iron inside the brain.
Top 5 publications from Parkinson’s UK research from the past 5 years
(drum roll) … here’s the top 5 most cited research articles and the Parkinson’s UK research projects they resulted from. We’ve limited the list to articles that focus on research areas directly relevant to Parkinson’s.
- Developing new methods for delivering treatment (550+ citations). Matthew Wood at the University of Oxford was awarded a grant, “Delivering RNAi to the brain to reduce alpha-synuclein”, which resulted in the work for this paper.
- Identification of genes that increase the risk of developing Parkinson’s (500+ citations). Two Parkinson’s UK grants contributed towards this paper. One was awarded to Gavin Hudson at the University of Newcastle to investigate “Changes in mitochondrial DNA in Parkinson’s”, and the other was awarded to John Hardy at University College London which is discussed above.
- The PDGene database for genetic information on Parkinson’s (340+ citations). Another appearance from John Hardy! Again, this paper utilised the work from his grant to find genes that make people more likely to develop Parkinson’s
- How the batteries of cells interact with genes in Parkinson’s (280+ citations). Dario Alessi at the University of Dundee was funded to answer the question, “What does the PINK1 gene do in nerve cells?” and this work resulted in the above highly cited paper.
- Different kinds of brain cells work together to release dopamine (270+ citations). This paper resulted from two different grants to the University of Oxford. One grant was awarded to Stephanie Cragg to understand the factors that control the release of dopamine from brain cells, and another was a grant to Richard Wade-Martins at the University of Oxford to speed up new treatments for Parkinson’s at the Oxford Parkinson’s Disease Centre.
To easily gain access to many of the papers cited in this blog post, you can download the browser plugin Unpaywall.
High impact journals
As well as high impact articles, the academic journal that the article appears in is also connected to impact. Some of the most well-known high quality journals are Nature, Science and Cell. Getting an article published in these journals can be difficult as they only publish very high-quality research which have results of great significance.
Journals have a measure of prominence called an ‘impact factor’. This is the yearly average number of citations each article in the journal receives. The higher the impact factor, the more times articles in that journal are cited. Many of our researchers publish in the journal Movement Disorders which has an impact factor of 7.1, meaning that articles published in Movement Disorders are cited on average around 7 times a year.
In 2016, Dr Carl Counsell and Angus Macleod published research in a high impact journal called The Lancet, which has a huge impact factor of 44. The article described a new model to predict the risk of mortality in people with Parkinson’s based on measures of movement, age and other conditions. There is still more work to do to ensure the model is accurate, but the researchers hope it will help tailor treatments to each individual and improve clinical trial design in future.
A good measure of impact?
With impact factor for journals linked to citations should we assume that this is a good measure of the impact of a piece of research?
Citations can be used as a rough measure of the influence of an article but there are a few caveats to bear in mind. There are a number of reasons a researcher may choose to cite a certain article:
- Because the cited research findings are widely accepted
- The cited findings are different to my findings
- Our methods are an improvement on the cited methods
As you can see, you might cite an article for positive or negative reasons. In some cases, a paper could have many citations because the methods or findings are widely criticised. Therefore, while having high numbers of citations can be an indication of influential research, this is not true for every article.
Citations can also take a very long time to accrue. The graph below shows that articles published in 2012 have on average more citations than articles published more recently. It can take a number of years from an article being published before it gains citations from other articles because research takes a long time to plan, carry out and then publish. You can find out more about the process of publishing scientific results in our related blog post Do researchers share their findings with each other?
Another criticism of citations is they only measure the academic reach of a finding in the scientific literature rather than to the wider public.
To get a sense of which findings had a big impact for the general public as well as other researchers, we’ve put together the top 5 articles based on the number of tweets they received on twitter in 2016. This shows the immediate impact of papers published recently, without having to wait for academic citations to accrue. We only included publications directly relevant to Parkinson’s in this list.
Top 5 articles by tweets in 2016
- Apathy in Parkinson’s could be due to reward insensitivity (73 tweets). A grant awarded to Richard Wade-Martins at the Oxford Parkinson’s Disease Centre to speed up new treatments for Parkinson’s contributed towards this paper.
- A phase 2 trial of Rivastigmine for gait stability in patients with Parkinson’s: (70 tweets). Emily Henderson at the University of Bristol published this paper as a result of her grant, “A drug trial to improve balance and prevent falls”.
- Similar brain changes found in people with early Parkinson’s and people with a sleeping disorder. (63 tweets). This is another paper from the researchers at the Oxford Parkinson’s Disease Centre.
- Understanding how brain cells signal movement (58 tweets). This paper is again a result of work by researchers in Oxford, including grants to Stephanie Cragg and Richard Wade-Martins.
- The prediagnostic phase of Parkinson’s (42 tweets). This article arose from a grant awarded to Alastair Noyce at University College London to find out, “Can we predict Parkinson’s?”
If you want to find the number of tweets, lookout for the round Altmetrics badge shown below on the website featuring the paper. This will take you to a page which outlines the social media coverage, showing individual tweets and blogs, as well as the locations of the coverage across the world.
The figures in this post are a snapshot and will change as papers are cited and tweeted more and more.
