Psychopathology: description and classification.

DSM-IV's strong empirical base has yielded an instrument with good to excellent reliability and improved validity. Diagnostic reliability depends on both the clarity and validity of diagnostic criteria and the changeability of disorders over time: The reliability of schizophrenic spectrum disorders, personality disorders, and some childhood and adolescent disorders remains problematic. Findings on diagnostic validity appear paradoxical: Attempts to validate schizophrenic spectrum disorders with neurobiological and genetic-familial validators have been only modestly successful, whereas the tripartite personality trait model has differentiated a range of depressive and anxiety disorders. Research on comorbidity has identified several highly comorbid disorders (substance-related disorders, personality disorders, depression, and anxiety) as well as some adverse consequences of comorbidity. The advantages of dimensional approaches to diagnosis have largely been demonstrated conceptually; ultimate conclusions about the strengths and weaknesses of dimensional and syndromal methods await substantial additional empirical research.