I have it. I'm pretty introspective, too. I'd say it's almost certainly physical in many if not most cases. I can actually feel that. The thoughts and mental energy normally ran smoothly through my mind. After injury to back & center, especially the stress of it, it's as if a shockwave went through my mind blowing fuses or something. That's best way I can describe feeling and effect. Certain paths and things just aren't there or light up when they shouldn't. The wiring from input(s) to outputs(s) is broken where it's no longer performing the function it should.

Far as stress aspect, it similarly ignites electrical and biochemical activity that flows through sensitive parts of the brain. We know those parts organize themselves expecting certain flows or weights. I'd default on position that they could be damaged by overflows slamming them. They'd get damage resulting in impaired function with rerouting of sorts attempted. The result would be replacing that function or maybe new + old happening side-by-side with old still broken. Would explain intermittent failures that seem to relapse to an imprint of whatever caused the stressor.

So, just a few thoughts combining what I learned studying those parts of the brain with my own experience of how a broken one works and doesn't.