A few weeks ago, the parents of a Harvard student told Dr. Richard Kadison, the chief of the university’s mental health service, that they suspected their daughter had a serious drug problem.

“The student in question argued that, although she needed some help, her problem was not substance abuse,” Dr. Kadison said. “From my standpoint, the problem was not who’s right and who’s wrong or what’s the diagnosis, but whether she is getting the right help.”