Keith,
I did not say iron caused PD. It is not known whether iron causes PD or PD causes accumulation of iron. It is however known that people with PD have a large accumulation of iron in their brains.
Yes PD has been diagnosed at 3 and people have lived to 120 without contracting PD, but what does that prove? It simply means that the 3 year old has a very defective BBB, whilst the 120 year old has a perfect BBB which has not deteriorated much with age. If the average age of death is say 75, why isn't the 120 year old dead? One can use these fallacious arguments to confuse.
You put words in peoples mouths that they have not said, I also did not say that " Parkinson's Disease is due solely to a loss of function of the blood brain barrier.". I could not make such a wild claim, I am simply putting this forward as a possible cause, but there may be other causes. However, sticking to facts, it is very significant that Parkies have been found to have defective BBB's in the work by the Dutch group led by Prof. Leenders.
I am glad you feel your brew "is overcoming to some extent some deficiency of the blood brain barrier.", since you are agreeing the BBB is defective in PD. (Just quoting you out of context, as you do!!!) LOL.

Ron