Cookie00,
That is a good question and your going to get mostly answers of people who tend to isolate and avoid alot. The main problem with people who suffer from PTSD is that it is an anxiety disorder that can become very disabling because the situations your describing can be very triggering and create a sudden bout of severe anxiety. And what happens is the body of a person who suffers can suddenly fill with cortizol and after the first 7 minutes that flood begins to create an overwhelming sense of confusion in the brain. So what most people who suffer do is often run and hide and not truely realizing it, tend to avoid these situations that bring on that sense of being overwhelmed. Stablizing a person who is in the throws of an anxiety attack is a challenge and should include them being removed from noise and extra stimulation and providing a quiet space with a presense that is quietly supportive and soothing.
Often a guide of helping is slowly talking to the person suffering and telling them to repeat to themselves to only focus on the moment, that everything else is not important, repeat that over and over in a very safe quiet atmosphere. Also medication to treat the anxiety can and may be administered to help the person relax and calm down.

Never, address a person experiencing this in a loud controling manner, it can make them worse.

What you can do is research this as well on line by typing your question in the search bar for PTSD. I have found that I have gotten more information by asking questions rather than just typing in PTSD.

Open Eyes