Jaye,
Thanks for your enthusiasm, and a very good question. I missed exercise, and have only found references which are confusing as to the effect on BBB permeability.
Rick, Your reference is a bit too medical; to follow exactly, but it does seem to be possibly a trojan horse type of crossing the BBB. I don't think it hasd a direct connection with what I have proposed.
Paula,
I don't think the immune system plays a party. What I am saying is,
Assume the permeability of a perfect BBB is say 100, where lower is less permeable, and higher is leaky or defective.
At 100, it lets levodopa pas through it, but not dopamine. If dopamine is allowed through at a low rate, when the permeability is say, 130, then when this threshold is reached, we start to show PD sym[ptons
I imagine people will be born with permeabilities ranging from say 90 to 110, averaging at a 100. Those people who start at 110, will reach the threshold of 130 sooner than the rest and will be young onset. Those who start at 90, may never reach 130, and won't suffer PD in their lifetime.
Our score will increase with age and environmental insult, like pesticides, and those of us starting with a permeablity of say 110 or over will soon reach 130. The leakage rate will be low at those levels, and our symptoms mild.
Taking things like curcumin will slow the rate of increase from 110 to 130 or over. Acute stress may bump up the porosity to say 150, and would cause dopamine to flood out. It probably goes back to the value just before the stress. The numerical values are of course pure fiction to try to explain what I am proposing. I hope it shows better what I have posted.
Previously, I always thought of leakage of toxins INTO the brain, but I then realised that in a defective BBB, molecules like dopamine, which can't ordinarily enter through the BBB, can also leak OUT.
Thanks for your inputs.