Diagnosing Psychological Disorders: Foundations in Classification o Clinical assessment vs. Psychiatric diagnosis Assessment - idiographic approach - what is unique to this person (personality traits, family background, culture, other circumstances) Diagnosis - nomothetic approach - applying what we know about a person to what we know about people more broadly. Seeing if specific problems fit with a general class of problems. Both are important in treatment planning and intervention o Diagnostic classification Classification is central to all sciences Develop categories based on shared attitudes o Terminology of classification systems Taxonomy - classification in a scientific context Nosology - taxonomy in psychological/medical contexts Nomenclature - nosological labels (e.g. panic disorder) Diagnosing and Classifying Psychological Disorders o Two widely used classification systems
International Classification of Diseases and Health Related Problems (ICD-10); published by the World Health Organization Diagnostic and Statistical Manual of Mental Disorders (DSM); published by the American Psychiatric Association; currently on DSM-5 (2013) o The Nature and Forms of Classification Systems Classical (or pure) categorical approach - Categories Yes/No decisions. Each disorder viewed as fundamentally different from others. Clear underlying cause. Individual required to meet all requirements for classification Useful in medicine. Know diagnosis, know treatment Views as inappropriate to complexity of psychological disorders Dimensional approach - classification among dimensions Symptoms or disorders existing on a continuum (e.g. 0 to 100) Patient might be mildly depressed (60) and moderately anxious (70). Create a profile to represent person’s functioning No agreement on number of dimensions or which dimensions required Prototypical approach - both classical and dimensional Categorical (yes/no decisions) but individual does not have to fit every symptom. Rather, patient must meet some minimal number of prototypical criteria (e.g. 5 of 9 depression symptoms) Creates within-category heterogeneity Presumes homogeneity within the “yes” and “no” group Purposes and Evolution of the DSM o Purposes of the DSM System Aid communication Evaluate prognosis and need for treatment Treatment planning o DSM-I (1952) and DSM-II (1968) Both relied on unproven theories and were unreliable o DSM-III (1980) through IV (2000) Atheoretical, emphasizing clinical description not underlying etiology Detailed criterion sets for disorders Emphasis on reliability (inter-rater; test-retest) Questions about validity Many decisions were not empirical (why have to have 4 panic attacks in a 4 week period; why have to be depressed for 2 week; why 5 of 9 symptoms) Spitzer on NPR DSM-5 (2013) Emphasis on understanding that many (most) symptoms aren’t specific to a single disorder but cut across many disorders (e.g.