My position is that being a celebrity isn’t very good for your mental health and probably attracts people to its ranks who are a bit unstable (I would cite any of the recent Big Brother contestants as evidence for this). But this is only on the basis of anecdotal evidence and not rigorous. The point you make about us hearing about celebrities mental health problems more is a valid one. They may have no more mental health problems than the rest of us, it’s just that they are reported more giving an incorrect impression. If we were to conduct a scientific study this problem would be called a bias – specifically an observation bias in this case.