My wife had panic attacks for years until she was persuaded, for other reasons, to stop using caffeine and artificial sweeteners. A couple of months later, her panic attacks stopped, and they haven't returned. She's convinced one of the sweeteners -- she mostly used cyclamates, but also some sucralose -- screwed with her brain chemistry. (She's always avoided aspartame as it gave her a splitting headache, so it wasn't that.)

There are plenty of reasons to avoid artificial sweeteners, so I wouldn't necessarily weight this anecdatum too heavily, but I thought it worth passing on anyway.