A number of clinical trials of potential PD therapies have ended unsuccessfully even though some of the participants claim that the impact of the therapies under test has been positive for them. It is easy to put this down to "noise" in the data, or to issues of statistical significance, or to the placebo effect, but it may be wrong to do so. We all come with different genetics, different environments, different medical histories, etc. So we will not all react in the same way to a therapy. I am concerned that therapies which are good for some people with Parkinson's are not being identified because of this one size fits all strategy.
The correct level of running trials should be the individual. What I am interested in is whether a therapy works for me. A therapy that cures me is still a cure even if it does not cure anybody else.