Developing and validating Parkinson’s disease subtypes and their motor and cognitive progression

“This is a really interesting study not only because it has identified novel sub-types of people recently diagnosed with Parkinson’s, but it may also point toward how we can better focus clinical trials of novel therapies. By carefully targeting specific experimental treatments at particular clusters of PD, we may be able to a.) develop a better understanding of underlying biology of Parkinson’s, and b.) increase our chances of success with the clinical testing of novel therapies. By comparing treatments across all 4 clusters of PD, we may be missing positive effects in certain subtypes of the condition.”

The large amount of variation in symptoms between individuals diagnosed with Parkinson’s has been an area of interest for the PD research community for a long time. It has led to many investigators proposing the idea that rather than being a singular ‘disease’, Parkinson’s may in fact be a ‘syndrome’ – a set of medical conditions that differ in their underlying cause, but share a very similar appearance. To evaluate this idea, several long term studies have been conducted which have assessed the clinical course of the condition in large groups (or cohorts) of people with Parkinson’s. The results of one such study have just been published.

Using data collected from 2500 people recently diagnosed with Parkinson’s (less than 3.5 years since diagnosis) across multiple research clinics across the UK. Upon analysing all of the data, the researchers identified four clusters of Parkinson’s based on this criteria:

1. a fast motor progression group with symmetrical motor disease, poor olfaction and postural hypotension
2. a mild motor and non-motor group, with intermediate motor progression
3. a more severe motor group, with poor sleep and intermediate motor progression
4. a slow motor progression group that has tremor-dominance and a unilateral nature to symptoms

The data from the 2500 individuals involved in the study came from two independent cohorts, and the four clusters appear to be rather stable across those two databases. This new study differs from previous cross sectional studies of PD in that all of the participants were recently diagnosed and of a similar disease duration.

Future research efforts will build on these initial results, by firstly assessing the longer term outcomes for each of these clusters – determining how these clusters may change over time. In addition, the investigators would also like to examine the reasons for these differences. And the results of these investigations may have important implications for how we stratify Parkinson’s and how clinical trials are conducted.

CamPaIGN study of Parkinson’s – https://jnnp.bmj.com/content/84/11/1258?ijkey=59008ae662cfd227905fbfd9d4ec22638b7b6080&keytype2=tf_ipsecsha   (funded by CPT)