Perhaps the reason that some INTPs seem to suffer from depression, anger etc is because due to society misunderstanding the needs of the INTP (such as needs for space, etc)...I also think that because INTPs' emotional stimuli comes from ideas rather than being around people. This could confuse ExFxs who see others' views by putting themselves in others' shoes, but they can't do this with INTxs because they would hate not being around others.
I realize that a lot of INTPs think that they are not influenced by others' opinions, but humans have evolved to be social creatures, whether we like it or not
The levels of this depends on the individual, of course.
People tell me that I shouldn't analyze too much, that it gets me down, but I'd rather analyze and be down then be oblivious...Now I am happy because I realize that I have the freedom to do this and not be in the dark.
I think that experience (and when I mean experience, I mean experience in thoughts/ideas as well as situational) is more important than its emotional anchorage. I think that emotions are only meant to accompany a situation, not to dominate it.
Just my opinion x)