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How could the DSM be improved? Critics say the A.P.A. should start by holding every diagnosis to tough scientific standards. Antiquated notions about deviant sexuality should be brought up to date or scrapped altogether. McHugh of Johns Hopkins suggests that the DSM become more than a laundry list of symptoms--some of which are always going to be ambiguous--by organizing psychiatric conditions around what he calls their "fundamental natures." Accordingly, he would use four categories of disorders: those arising from brain disease, those arising from problems controlling one's drive, those arising from problematic personal dispositions and those arising from life circumstances. While such groupings are imperfect--is alcoholism caused by a brain disease or a problem in controlling one's drive, or a little of both?--they at least get clinicians focused not only on the symptoms of an illness but on its possible causes as well.
In the end, though, the DSM can't achieve certainty because psychiatry can't. Unless brain researchers discover exactly how neurological mechanisms become abnormal, the DSM will always include more hypotheses than answers. Which means all those guys fantasizing about tennis outfits are probably just weird, not certifiable.
For more information on mental health, visit time.com/mindbody