But regarding your question about mental health symptoms emerging later in life, yes it is possible, especially in the case of sustained substance abuse which over time can damage the brain. Of course, substance abuse can also mask symptoms of mental illness which may not become evident until after the substance abuse stops or is curtailed.
I see a lot of mental health professionals speculating about or providing diagnoses for Charlie Sheen in the media . I think this is utterly unethical. Those involved need to go back to school and re-take Ethics 101. It's also pointless: You cannot diagnose someone you have never met. That's what separates the Dr. Phils of the world from real mental health professionals.