Yeah, it works. EMDR has been shown to be an effective treatment for PTSD in multiple randomized controlled trials. I’ve done it myself.
The question is why it works. Most clinicians seem fundamentally uninterested in figuring that out. There is a strong contingent of behavioral researchers who believe it works because it’s effectively prolonged exposure therapy “with a purple hat” - meaning the bilateral stimulation stuff is superfluous. As someone who has done both prolonged exposure therapy and EMDR and had substantively different experiences, I am skeptical of this claim.
We have inklings of why it might work. There are some studies, for example, that show playing Tetris after a traumatic experience makes you less likely to develop PTSD. Why? The prevailing theory is that keeping your working memory busy allows for memory consolidation (that is, the memory can be integrated as narrative memory rather than traumatic memory - they appear to be two different processes in the brain.) So it’s possible that EMDR works by keeping your working memory busy so that your traumatic memory can quietly be consolidated as narrative memory in the background.
But we don’t actually know. As someone who was helped a lot by EMDR, I find it frustrating that no real gains have been made to understand how it works. This makes it a lot harder for it to be accepted in the evidence-based psychological community.
ETA: I made this thread about it many years ago. EMDR helped me so much that I don’t even recognize the person I am describing myself as being, there. Those issues are gone.
Over 30 randomized controlled trials have shown the effectiveness of EMDR.