Reacción a "Reactions: movement data can predict Parkinson's risk years before diagnosis"

The article is very interesting. It is based on a cohort of thousands of people whose spontaneous movements were measured (with an accelerometer on the wrist) during one week years ago. It has been studied whether this data predicts whether or not they will suffer from Parkinson's later on. A very strong correlation has been found between people who move little and slowly with future Parkinson's disease. These data are specific to Parkinson's and do not predict other neurological diseases (e.g. other dementia such as Alzheimer's or dystonia) or joint diseases (osteoarthritis).    

I think the article is of good quality, although it is based on methodologies (cohort selection and specific statistical analyses) that I do not use in my work and do not know well.   

It fits very well with current knowledge. Other authors had previously described that slowness of movement is a characteristic feature of some people who subsequently develop Parkinson's disease. These studies had been done in pre-selected cohorts (at risk of developing Parkinson's) and were carried out in a hospital (i.e. they required the intervention of healthcare staff to do the movement analysis). The current study is carried out in the general population in a very large cohort and the analyses are done automatically, based on the data recorded with the portable accelerometer. This is novel and very interesting, as it is relatively easy to do in the general population.   

There are easily recorded "prodromal" symptoms that allow a prediction to be made several years before the onset of the disease with a much higher reliability than previously obtained with genetic, lifestyle or recording analyses of symptoms that are considered prodromal for Parkinson's (such as anosmia or constipation).        

What could be the advantages, given that there are no preventative or targeted treatments for the cause?

This is, in my opinion, the most debatable aspect of the study. Knowing ten years earlier that you have a high risk of developing Parkinson's is very interesting and valuable from a scientific point of view (it opens up new perspectives for research into the pathogenesis of the disease and, among other advantages, allows the efficacy of new protective drugs to be tested). In addition, the future patient is given the opportunity to prevent/palliate his or her disease. However, given that such prevention is not yet possible, it is not clear that this is of any benefit to the future patient. This is an issue with important ethical implications. The same is true for other diseases.