Sooner or later most of us suffer deep grief over the death of someone we love. The experience often causes people to question their sanity--as when they momentarily think they have caught sight of their loved one on a crowded street. Many mourners ponder, even if only abstractedly, their reason for living. But when are these disturbing thoughts and emotions normal--that is to say, they become less consuming and intense with the passage of time--and when do they cross the line to pathology, requiring ongoing treatment with powerful antidepressants or psychotherapy, or both?

Two proposed changes in the “bible” of psychiatric disorders--­the Diagnostic and Statistical Manual of Mental Disorders (DSM) --­aim to answer that question when the book’s fifth edition comes out in 2013. One change expected to appear in the DSM-5 reflects a growing consensus in the mental health field; the other has provoked great controversy.