When I say depressed, I mean it in the literal sense. Depression, it can strike anyone, and even if ENFP's seem happy go lucky 24/7, they've got a dark side too. More often than not it will not come out because of the ENFP nature to always look on the bright side, but given a bad enough situation and a smack into reality, these are the stages of what a depressed ENFP will go through.
Stage One: ENFP will start feeling a bit lonely and disconnected. They will think it's just a stage that will pass, and will try to ignore it.
Stage Two: The ENFP will start feeling even more lonely, this can usually be brought about by having a hard time with family or feeling like they are insecure in their relationships in general. Stage One increases, and the ENFP will start feeling anxious.
Stage Three: The ENFP's feeling of anxiousness will become overbearing, and they may feel extremely insecure when talking to other people. They lose the quick wit and charm they used to have. The smile will because more nervous and the laugh will become less natural. They will still be trying to convince themselves it;s just a stage that they are going through and that nothing is wrong.
Stage Four: ENFP will most likely hit shut down mode. They will not talk to other people about their feelings or what is going on unless asked specific, prying questions. They will have a really hard time talking to people and feeling like they can relate. They will start coming across as an introvert.
Stage Five: The ENFP will be extremely stressed, lonely, and emotional. May start bursting out randomly and be extremely moody. Will experience periods of highs and lows. The ENFP may start crying over something seemingly insignificant. They will do this because there is so much bottled feelings up inside and that may have been the last thing to set them off edge.
Stage Six: The ENFP will start lashing out at other people like above, but more extremely. Will most likely show complete and utter disregard for authority. They will also start hurting the people they care about, to make them back off and go away. All the while the ENFP, through the stages, will try to convince themselves that nothing is wrong and that they will get better, and thus the problem worsens.
Stage Seven: They will finally admit to themselves that there is a problem but try consciously to contradict it. They will try to force themselves to relax and be wonderful again. They will try to establish the facts- what the problems is, how it went wrong, and what to do.
Stage Eight: If it gets worse at this point, the ENFP will not be acting like themselves at all. They will not be thinking clearly, and will most likely suffer from being illogical, irrational, and as well may suffer from extremely headaches. They will give up on caring and will not pay attention to the world around them, instead focusing all of their energy into their inner world of what they feel and dwell on it. They will no longer have any motivation to care or do the things they love.
Stage Nine: Your ENFP will start enjoying dark humor ad freaking other people out for the hell of it, especially the people they care about. However, at this stage they will not do this too extremely to the people they care about because their is that small piece of the ENFP that wants to hold the relationship in tact. They will push you away and drag you back in, and become and emotional roller coaster for anyone and everyone around them. If you ask what is wrong, the ENFP will completely shoot you down unless it is in a structured environment and they think that you are somebody that they can trust. However at this point the ENFP will become extremely untrusting, so talking to them about anything is much like walking on fragile glass about to fall apart and break forever. The ENFP will hold grudges.
Stage Ten: Complete personality turnaround, the ENFP will have lost it, or will have appeared to. Complete emotional instability and recklessness. They will be completely and utterly impulsive to the point of stupidity. They will not care about their well being or anybody else's. At this pion, the ENFP will be so far in their heads it will be nearly impossible to get through to them unless you sink to his or her own level of insanity and instability. They will have given up on life altogether, and will most likely have forgotten what it was like to really feel alive and well again.
I've seen about 2 extremely unhealthy ENFP'd in my lifetime and this is what I have experienced. This is still in edit mode, basically a thesis, so please correct me if I'm wrong. I would like this to be as accurate as possible, and additional information would be great.