system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why the difference between shell shock and PTSD

I thought it was roughly the same updated concept but I just saw videos of shell shocked soldiers and they were shaking, had a lot of trouble walking, tics, etc. I might just have a very narrow idea of post-war PTSD (don't live in the US) but I thought it was mostly anxiety, fear of noises, depression - mental things. Any ideas?

(Edit: whoops, the Why in the title is an intruder)
gpt
What people used to call "shell shock" was likely a combination of PTSD, traumatic brain injury, and other neurological and psychological issues arising from war and being regularly exposed to bombardment and gas attack.