Unfortunately, you are treading extremely close to saying "high IQ = mental illness". I don't think it has to be that way or should be that way. If I live another fifty years, hopefully I can make some headway on changing that general status quo (edit: I mean the very common view of "there is a fine line between genius and insanity" and the high social stress so many intelligent people routinely endure, yes, at a cost to their mental health).
I don't think I'm treading that line. Having an IQ that is a few standards of deviation higher than average makes a person quite different from average people... just as a person with average IQ would feel out of place among a group consisting mostly of people with IQs a few standards of deviation below average.
However stress is stress. People of any IQ feel stress from a variety of factors. One purpose of the human emotional system is to deal with stress and to respond appropriately... sometimes this means flight, sometimes fight, sometimes take a deep breath, etc. Healthy emotional development is separate from IQ and very dependent on genetics and environment.
Pretty much anyone who isn't completely average in all respects is going to find some kinds of interactions with other humans stressful. So I think that it's tough to make the case that certain traits like high IQ are inherently more stressful or make a person more likely to display mentally unhealthy behavior.
Which is why I think there is a general quality of mental health, which can get better or worse in the same person over time (and can change quickly and slowly)... which is an accurate descriptor of the meta factors that contribute to the proper functioning of the person's cognitive and emotional systems to respond to the inevitable stresses of daily life.
