I don't think those questions really confirm anything. One of the problems is recall bias as well. We know that people often confound the different medications that they've been given, and sometimes that's one of the criticisms of surveys that are conducted after the fact. However, asking people questions gives you perhaps a sense of what the issue might be, but what we lack is a definitive test whereby we can confirm whether that is the case.
I should also point out that matters of the brain are very complicated. We understand very poorly the brain and brain functioning. Particularly in a combat environment, the exposures to multiple different traumas really confound matters a lot as well, so I think asking those questions has no real validity at all.