Note that the TNF-a referred to above is the same cytokine that is the villain in the activation of the microglia.

I suspect that inflammation is the Big Dog. It comes from multiple sources, including stress. It causes a variety of problems, including BBB failure.

I keep coming back to Ron's tooth. (Leave it to science, Ron.) The abscess was churning out chemicals that, in turn, triggered similar actions behind the BBB. Those cytokines disrupted his brain function while also making his BBB leak.

Here is an interesting wrinkle-
http://www.sciencedaily.com/releases...0708181204.htm
"... supports the idea that toxic levels of amyloid beta protein, the substance scientists believe is responsible for Alzheimer's disease, accumulate in the brain because a pump that pushes it into the blood and past the blood-brain barrier malfunctions.

The blood-brain barrier is a system of cells that regulates the exchange of substances between the brain and the blood. The blood-brain barrier transporter known as LRP is the pump that removes amyloid beta protein from the brain and into the bloodstream.

"LRP malfunctions like a stop light stuck on red, and keeps amyloid beta protein trapped in the brain," said Banks, who also is a staff physician at Veterans Affairs Medical Center in St. Louis."