Depression too often reduced to a checklist of symptoms

How can you tell if someone is depressed? The Diagnostic and Statistical Manual of Mental Disorders (DSM) -- the 'bible' of psychiatry -- diagnoses depression when patients tick off a certain number of symptoms on the DSM checklist. A large-scale quantitative study now shows that some symptoms play a much bigger role than others in driving depression, and that the symptoms listed in DSM may not be the most useful ones.