DSM-5 lends new urgency to brain-based evidence for mental illness.

he inclusion of new classifications for such typical childhood behavior as temper tantrums in the upcoming version of the Diagnostic and Statistical Manual of Mental Disorders is lending new urgency to research aimed at finding empirical evidence for psychiatric disorders. The new edition of the manual — known as DSM-5 — due to be published this month, updates the previous 2000 classification of mental illnesses. It creates new categories and updates the symptoms, both those required and those excluded, to make a diagnosis of particular mental illnesses. The changes have already provoked criticism from a previous editor of the manual and other leading psychiatrists They contend the new edition will pathologize normal emotional reactions. The new manual, for example , opens the possibility for doctors to diagnose grief following bereavement as a depressive disorder. Although these new categories are promoted as addressing the wealth of advances in neuroscience, other psychiatrists and neuroscientists believe new research can make important contributions to diagnosing mental illnesses that are not based solely on symptoms. The Research Domain Criteria project at the National Institute of Mental Health (NIMH) in Bethesda, Maryland is one such contender. That project plans to categorize mental disorders based on objective brain abnormalities, using brain imaging. Under the project, groups of people with a heightened or lowered response in the amygdala (an area in the brain partly responsible for emotional regulation) would be categorized as having separate psychiatric diseases, regardless of the symptoms they express (Am J Psychiatry 2010; 167: 748-51). " We're always going back to the symptom complexes of the DSM as the gold standard to identify psychiatric disease. But this is very limiting, " says Dr. Thomas Insel, the NIMH's director. Using symptoms to diagnose mental illness is equivalent to making a fever — a common symptom of infectious disease — the " gold standard " for infectious disease, Insel says. " Of course, not everyone with a fever has a positive blood culture. " News CMAJ DSM-5 lends new urgency to brain-based evidence for mental illness The DSM-5 relies on symptoms for diagnosis, but some psychiatrists and neuroscientists believe physical evidence, such as biomarkers, and assessing brain abnormalities through brain imaging, can also be used.