"Communities" of Conditions: Novel Methods for Classifying Psychiatric Disorders.

In 1798, Philippe Pinel presented one of the first nosologies for psychiatric disorders, "Nosographie philosophique ou la méthode de l'analyse appliquée a la médecine."1 His emphasis on psychological and physical conditions as the basis of mental illness provided a distinct departure from prior reliance on such etiologies such as demonic possession. Establishing classification schema was a much more profound innovation than a simple academic reordering of psychiatric phenomena-under Pinel's leadership at the famed Pitié-Salpêtrière hospital, it also led to a radical reformation of clinical interventions, moving away from pseudoscientific practices toward psychologically based interventions. Much of this work influenced his successors in psychiatric taxonomy including Emil Kraeplin and others, ultimately forming the basis of the DSM.2 Although the DSM has been subsequently celebrated and maligned, it has been instrumental in both our conceptualization and treatment approach to psychiatric disorders. Indeed, there has been extensive effort to validate these conditions using factor analytic approaches to confirm that such conditions represent cohesive biologically based disorders, which has presented challenges.3.