Psychologists James Pennebaker and Shannon Wiltsey Stirman published some research on poet suicide in a 2001 “Psychosomatic Medicine” article you can read here.
Comparing the texts of suicidal and non-suicidal poets, they found the work of suicidal poets “contained more first-person singular self-references throughout their careers. That self-references do not increase over time indicates that the suicidal poets’ level of preoccupation with self is not due to a factor such as increasing levels of fame or recognition of their work over time. Additionally, the use of the first-person plural, which might indicate an awareness of and an integration in social and personal relationships, was lower in the suicide group’s poetry than it was in that of the nonsuicide group. Consistent with social integration theories of suicide, the direction of the effects for communication words (eg, talk, share, listen) indicates that the suicide group might have shown a decreased interest in social relationships as they approached the last years of their lives. The poets who ultimately committed suicide also used more words associated with death than did the nonsuicidal group. Surprisingly, though, the amount of negative or positive emotion did not vary significantly between the two groups.”
This makes some intuitive sense -- put the words “self-obsessed” and “poet” together, and names that immediately come to mind include John Berryman and Sylvia Plath... I even wonder if, when we get excited about self-destructive artists, it isn’t primarily the self-obsession we’re relating to, rather than the suicide? Wasn’t self-obsession equally the quality that America responded to in James Dean and Marilyn Monroe?
Regarding the writer suicides that most horrified me in 2008… while I always saw Thomas M. Disch as among the least self-obsessed of writers, towards the end he did start playing around with the conceit that he was God. In a satirical spirit, obviously, but perhaps it was still a symptom of self-preoccupation? Whereas David Foster Wallace’s way of being unhealthily obsessed with the self was to constantly preach against unhealthy obsession with the self.
I suspect self-obsession is a side-effect of depression rather than a cause of depression? Although once you've really gotten started it must be a vicious spiral...