Well, first off Mrs.Gilman lives in the late 1800's early 1900's were physicians, doctors, and etc, used the word deranged or crazy quite loosely for individuals who did not see the same way as in their culture. I am not a psychologist, nor am I able to diagnose anyone in a way to be called deranged of any sort, but after taking a deep reading into this passage, I believe the longer Mrs.Gilman stayed stored away from the rest of civilation she became unbalanced.
Taking in the fact that when you do not have a mass of companions to speak to, you will begin to speak to yourself, see things that you wouldn't normally see, and endangering your minds ability to think realistically. But again, I do take in a fact that this was a little over a centure ago, were they believed if it's not right than it's not right.
People rarely thought outside of their own beliefs.
I do believe that there must be several women suffering from accidental derangement or accidental in captivity. Women living in strict muslim area begin to think that they are just objects in their man's world. In my eyes and beliefs I would suggest that that would clasify as being captive.