Any kind of change to scenery is going to be tremendously difficult on a person. I'm the type of person that likes to keep things simple and doesn't like to fix things if they're not broken. As far as culture shock goes, I would definitely not be able to handle the clash when visiting Paris if I ever did. I realize that it would take me a long period of alloted time to get used to the culture changes.
Culture shock just sort of happens when you are in a place that you are not used to. When you grow up or live in a one place and you leave after a long time any place will be a shock to the system. When things are different everywhere you go, the clothes, stores, language, and people, it can take a while to adjust even if you are well prepared for the trip.
Paris syndrome does not seem like a real affliction. Parisians are widely stereotyped as rude and hateful toward Americans. They are culturally portrayed as snooty. Having visited Paris myself I did feel a bit disillusioned that the beautiful city of lights was much like another other busy city in the world. The locals were not that unfriendly toward me, but I did not experience hallucinations or feelings of persecution and I don't think most visitors do either.
Things have happened across the globe. You can't be afraid to go places and enjoy your life because of it. This is how terrorism works and if you let it work when you go places, you let the terrorists win. I would not experience Paris syndrome because I wouldn't let the past get to me.