If going for a distraction, it needs to be natural, you can't say "hey you are looping so we are going to play with the cats to distract you before you go mental".
The principle is that the looping person needs to perceive a stimuli strong enough to break the cycle.
Another way that can work it can be to suggest they watch the loop like a movie and not live it.
It is also important to keep them talking, when tripping the mind goes 100x faster when silent then when talking, so the more they talk the more they slow down and can catch up with their thoughts and make sense of what is going on.
The chatting needs to be and feel natural.