Neuroprotection trials for PD are notoriously difficult to do - as was discussed at the PD World Congress in Glasgow last year. The effects can be subtle and PD's progression can be so variable between individuals, that you need to run a very large trial (many people) for a very long time.
“To achieve adequate statistical power, these trials will need to include thousands of patients.” (http://onlinelibrary.wiley.com/doi/10.1002/mds.20057/full
) but the QE3 Phase III study, reported in this thread enrolled only 600 patients – although, admittedly, this was much larger than the original study by Shultz et al. ("Effects of Coenzyme Q10 in Early Parkinson Disease") that concluded “The adjusted mean total UPDRS changes were +11.99 for the placebo group, ... and +6.69 for the 1200-mg/d group. …... and the difference between the 1200-mg/d and placebo groups was significant (P=.04).”
This is sad news, indeed, but I will continue to take my Coenzyme Q10 until I've read the a detailed analysis of the complete data set (which the Principal Investigators are working on).