I think you are exactly right. And long ago we all were talking about if we remembered constipation as an issue as children and roughly half of us did. One would think that figure rather high in a bunch of physically active kids. So we grow up stewing in our own juices. Our gut is, literally, a big sewer in that it is loaded with all those toxins that get blamed for PD. The bacterial endotoxins that I keep on about are plentiful in our food and air. The pesticides on that apple are there. Herbicides, too. The chemicals in our drnking water. Etc.

Our inflammatory state and BBB fluctuate hand-in-hand and anything that increases the former affects the latter as well. Stress, for example. Or the flu. Or h. pylori. All these familiar names.

As if the assault upon the BBB wasn't enough, there is a backdoor that bypasses it entirely which Braak described and a team from St. Judes recently observed an influenza strain actually using - the vagal nerves that connect the GI tract to the brain. The failure of the gut barrier would increase the odds of toxins and pathogens accessing this route. And they can even catch a ride on what is known as "ultrafine particulates" - soot. Diesel exhaust. Coal smoke. Like in London in 1817.

It is all coming together.