An interesting read, addressing a correlation between creativity and metal health. However, it also indirectly discusses the correlation between intelligence and mental health.
Creativity, Intelligence and Mental Health
Sorry, should have said thank you for posting this and commented how interesting I found this. There is a trait in our family of people being somewhat or completely unable to block out stimuli (DS, my mom...) and while I wouldn't call them "mentally unstable" you can tell how much it saps their emotional energy...
My friend and I were discussing this recently. A lot of people we know who show higher than average intelligence, creativity, etc. are also afflicted with depression, bipolar disorder, schizophrenia.. I thought it was more than a coincidence as well that many of past creative minds were also plagued by mental disorders.