Well I would imagine it didn't help make them very nice and well-socialised people anyway. Though from what I gather the Romans didn't appear to have particularly major problems with shell-shocked veterans no longer "fitting in" back in the civvie world, quite in spite of their longstanding Assyrian policies.

For that matter, the same seems to roughly be the case with the various more-or-less tribal warrior societies where perfectly regular Joes were commonly enough expected and called up to fight and kill and were rarely any nicer than anyone else in victory. And in some cases, at least if the Roman sources are to be believed, didn't even qualify as full adults before slaying a foeman...

No, assorted "war psychoses" don't appear to have been very common back in the day, inasmuch as can be gleaned from the sources. *Some* individuals do seem to display at least some of the symptoms of PTSD, but even among grizzled veterans it appears uncommon. Neither does it seem to have been much of a problem in the much better documented European armies of Middle Ages and later - before WW1, that is.