The monitoring and assessment of the symptoms/features of Parkinson’s is a big deal in the research community at the moment.
There is currently a mad hunt for ‘biomarkers’ – reliably measurable physical characteristics – that could help not only with the assessment of individuals living with the condition, but could also aid in the running of clinical trials by providing additional measures of efficacy/benefit.
Recently an interesting perspective was written by some of the leading researchers in this field.
In today’s post, we review what the perspective outlined, and we will discuss other aspects of the biomarker research that need to be considered by the wider Parkinson’s community.
Perspective. Source: Huffingtonpost
Scientific journals will often invite the research leaders in a particular field of investigation to write a brief journal article that deals with unique view of a common problem.
Articles of this nature are called ‘Perspectives‘.
And recently a very interesting perspective was published in the journal Science on the topic of biomarkers for Parkinson’s.
Title: Finding useful biomarkers for Parkinson’s disease
Authors: Chen-Plotkin AS, Albin R,….a lot of additional authors…, Zhang J
Journal: Science Translational Medicine, 15 Aug 2018, 10 (454), eaam6003.
This perspective included a rather long list of a ‘who’s-who’ of Parkinson’s researchers – both academic and industry. Even members of the Michael J Fox Foundation and Verily/Google Life Sciences were included.
The perspective sought to highlight ‘the “ecosystem” of shared biofluid sample biorepositories and data sets will focus biomarker efforts in Parkinson’s‘. It is a very enlightening read, one that begs for reader responses. But sadly the article is behind a ‘pay wall’, and so many in the Parkinson’s community won’t be able to provide any thoughts or feedback.
But not to worry, we can discuss the matter here. And the best place to start that discussion is with the obvious first question:
What is a biomarker?
A biomarker is an objectively measurable physical characteristic associated with a condition. It is a biological component of a condition that correlates with that condition in some way. For example, the DaTscan brain imaging technique provides a ‘biomarker’ for Parkinson’s by measuring the amount of dopamine re-absorption in the brain. By labelling the dopamine neurons with a radioactive marker, we can quantify the levels of dopamine activity in a person.
An example of a DaTscan. Source: Cedars-sinai
What did the perspective say about biomarkers for Parkinson’s?
At the Movement Disorders meeting held in Berlin two weeks ago, there was an interesting presentation dealing with a topic close to our hearts (literally).
In a previous post, we have discussed research suggesting that people (Danes) with vagotomies (severing of the nerves from the stomach to the brain) have a reduced risk of Parkinson’s disease – supporting the idea that perhaps the gut is a one site of disease initiation (click here to read that post).
At the meeting in Berlin, however, data was presented that failed to replicate the findings in a separate group of people (Sweds!).
Title: Vagotomy and Parkinson’s disease risk: A Swedish register-based matched cohort study
Authors: B. Liu, F. Fang, N.L. Pedersen, A. Tillander, J.F. Ludvigsson, A. Ekbom, P. Svenningsson, H. Chen, K. Wirdefeldt
Abstract Number: 476 (click here to see the original abstract – OPEN ACCESS)
The Swedish researchers collected information regarding 8,279 individuals born in Sweden between 1880 and 1970 who underwent vagotomy between 1964 and 2010 (3,245 truncal and 5,029 selective). For each vagotomized individual, they collected medical information for 40 control subjects matched for sex and year of birth (at the date of surgery). They found that vagotomy was not associated with Parkinson’s disease risk.
Truncal vagotomy was associated with a lower risk more than five years after the surgery, but that result was not statistically significant. The researcher suggested that the findings needs to be verified in larger samples.
Differences between the studies?
The Danish researcher analysed medical records between 1975 and 1995 from 5339 individuals had a truncal vagotomy and 5870 had superselective vagotomy. The Sweds on the other hand, looked over a longer period (1964 – 2010) but at a smaller sample size (3,245 truncal and 5,029 selective).
We must note here that the current research has not been peer-reviewed and we are presenting it here for interests sake. But it come after a series of correspondence regarding the original Danish paper were published in the journal Annals of Neurology. Those letters to the editor were from a group of researchers (believe it or not, mainly Norwegians) reported that an analysis of the same data sets used in the original study failed to find a significant difference between the groups – that is, no protective effect for vagotomies in Parkinson’s disease.
This Scandinavian debate has important implications for Parkinson’s disease, bringing in to question the idea that Parkinson’s disease may begin in the gut. Recently, there have also been several reports published suggesting that alpha synuclein present in colonic biopsies may not be as useful in diagnosing Parkinson’s disease as previously proposed.
And this is why the path of science is such a long one – interesting new findings need to be replicated before they can be added to our understanding of the world around us. And if those interesting results can not be replicated, then we have to ask ‘why?’
Watch this space.