"Intellectual curiosity" resulting in depression. I'd totally agree with that simply because asking too many questions, analysing everything can make life and socialising very difficult.
However to claim that it's "clever" or "intelligent" to act in such a way, is totally wrong.
Without being completely arrogant, I did view myself as someone quite intelligent back in high school: top of my class in a really good school and to be honest, anything academic I excelled at.
However, I realised later that there's a limit to everyone's abilities, be they physical, mental or other and I've ended up disagreeing totally with the notion of "intelligence".
The vast majority of people excell in certain areas and fall back in others. That's life. The only times that people end up believing that they're amazingly intelligent and distance themselves is when they LIMIT their view of intelligence to an area that suits them.
There are excellent talkers with amazing social skills but rubbish at anything analytical; There are people who can make quick decisions efficiently and then there are philosophers or mathematicians who are social recluses. I would NEVER claim that one group is more intelligent than the other.
How can a brainy kid, good at school be called "intelligent", if he can't establish good social relationships or is rubbish at making decisions. It's not to say that you can't have one with the other. Of course you can. But you should never look down on people, because in a limited area that you have set yourself, you excel more than others.
When I call up the plumber to get something fixed and he tells me that he was crap at school, I don't think "Boy, being at uni, I'm so much brainier than this guy". I think "This guy knows stuff that I don't know. He thinks in a way that I'm incapable of. Sure I could claim that I could easily learn but how sure am I?"