Do you have anything to support that claim?
Mostly anecdotes, especially among high-profile or famous people. Three off the top of my head that fit the chronic pain narrative are Dick Trickle, Hunter S. Thompson and Ray Combs. Then there was the case of Don Lapre who fits the "avoid those going after you" narrative (in Lapre's case, the feds, since he was being investigated for fraud).
Depression alone, from the cases I've seen, is generally pretty rare as an impetus for suicide, except in teenagers. Not that it doesn't happen (see: Sylvia Plath, Freddie Prinze Sr.) but that it isn't a leading cause and we shouldn't assume it as such.