Tim Robbits, the "personal power" guru describes a technique whereby you lure the person into the negative triggering memory and then surprise them with a non-sequitur or some random, disconnected act that gives them a real physically based panic (as opposed to a pure memory recall based panic).

he describes it as being like playing a record and then bumping the needle so it fucks up the recording, and can't be played anymore. after about two or three times being lured back to the memory, and shocked out of their panic, they can't panic about it anymore. you have dragged them through the reliving of something enough times that now there is a genuine empty space in their memory where they can now choose how to fill it. it no longer leads to another thing that is terrifying.