Since my brain injury, I've had trouble handling over-stimulation. I've continued to improve, and have developed ways to handle this issue pretty well, but for the first few years I would have a hard time focusing on what I needed to do. One baby screaming I could usually handle, but put me around a bunch of kids, and pretty soon I would be ready to run from the building. Not such a good thing if you are the parent in charge.
Luckily, I haven't had to be in charge of too many kids at once, and my wife has been able to handle many of the situations where I get flustered. I know when things are starting to be too much. My eyes feel like they get wider, and I'm pretty sure I begin to look like Gene Wilder in Young Frankenstein.
I try not to go to big shopping mega-complexes during rush hours. Stores like Home Depot are too much sometimes even on a weekday. Lists are a necessity. Grocery stores were an issue for a while, but as long as I am used to a store, I can usually get in and out with what I need.