In vivo and in vitro studies - because the contents of petri dishes, test tubes and genetically modified animals don’t get Parkinson’s and because legitimate ‘breakthroughs’ which are extremely rare won’t make it to market in my lifetime. If you are YOPD don’t give up.
Magazine & newspaper Articles – because nearly all have misleading (hype) titles and many incorporate misleading content. Researchers/drug companies need publicity to raise money.
Studies which rely wholly on the UPDRS – because he UPDRS does not measure constipation, depression, anxiety, or any non-motor symptoms which account for most symptoms and because any drug company knows or should know it’s limitations. Drugs that are measured solely on the UPDRS look more effective which explains why it is still in such broad use.
The MDS UPDRS is a vast improvement. Look for this in combination with the Hoehn and Yahr (HY) scale in the studies you read.
“The MDS‐UPDRS specifically covers a greater number of PD manifestations, including non-motor symptoms (NMS); better discriminates slight/mild manifestations of PD compared with the original UPDRS; resolves ambiguities and gives clear instructions for both raters and patients; and assesses all items in a uniform way.”