Missing: one word

I require a word which means "causes or is caused by". I suspect the English language does not possess such a word. This is a great trial to me in the process of writing an essay about a bunch of stuff for which we don't know which direction causation operates. Mostly I'm explicitly stating the causal ambiguity, and sometimes I say things like "is related to", but it's all very annoying.

(Essays continuing after official deadline because I was ill last week and have an extension. I fully expect to be writing essays forever, and never to reach Christmas.)

Edited to add: essay is finished :-) I will read through tomorrow to fix the inevitable bits where it doesn't make sense, but other than that: one down, one to go!