It would not surprise me in the least that in a large number of D/s or M/s relationships the bottom was codependent. The site I use for psychological information is mentalhelp.net and an example quote from there is "... a codependent submerges their needs for those of the other ..." which I know happens to subs (and from what I understand that is what can take some into sub-space). The subject has arisen for me twice now during negotiations (sadly neither of which worked out), and I would now recommend it be discussed between partners in our lifestyle as a possibility. The information on that site tells you what to look for and how to cope with it (from both sides).

Hope this helps
VV