Conduct disorder is a useful diagnosis for adolescents

Adolescent Psychiatry,  2002  by Weissman, Sidney H

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The question we have been asked to address is whether conduct disorder (CD) is a meaningful diagnosis for adolescents. In other words, does this diagnosis of an adolescent's behavior inform us about a particular adolescent, and does it enable us to communicate to colleagues and others meaningful information about this particular adolescent? Before we can address these issues, we must first review why medicine has established diagnostic systems to describe patients. Then, we must review the methods that were used in developing the diagnostic system for psychiatry with a particular focus on the diagnosis of CD.

ESSENTIAL ASPECTS OF MEDICAL DIAGNOSES

Reliability

A medical diagnosis is a shorthand that enables practitioners to communicate with one another about an individual without the need for detailed elaboration. For example, if we say that a patient has bipolar disorder (BPD) and is in a manic state, we have communicated a great deal about that person's current condition. Although the statement lacks information about particular actions of this patient and about the severity of his disorder, it provides us with an initial category that guides our questions and/or actions. By establishing a diagnosis, we also establish a framework to develop a plan of therapy. Again, if we are talking about someone in the manic phase of BPD, we would conceptualize the use of a mood-stabilizing medication as part of treatment. Our current diagnostic system does not inform us whether this patient might have a genetic predisposition to BPD. Although it addresses issues of stressors, it does not identify the meaning of stressors specific to the patient. Because of our awareness that each diagnostic category underwent extensive field-testing to establish reliability regarding its use by mental health professionals, we assume that the criteria that define and describe CD, BPD, and all other disorders appearing in the Diagnostic and Statistical Manual of Mental Disorder (DSM) have attained a consensus in the field of psychiatry. Because of the extensive fieldtesting, we may assume that the behavior one mental health professional calls bipolar will also be called bipolar by another appropriately trained individual. Armed with this knowledge, we can now potentially develop an effective treatment plan for our patient based on a diagnosis of bipolar disorder, manic state.

Validity

Now we address the validity of our diagnostic system and explore the assumptions that are built into it. Historically, diagnostic systems follow one of two approaches. The first approach establishes diagnostic categories on the basis of theory. The theory may or may not be based on verifiable hypotheses. In any event, the theory offers explanations of observed data and a means to label the data. In psychiatry, the theory offers a means of first labeling behavior and then prescribing a treatment for the patient's observed altered behavior. An example of a theory linked to a diagnosis is the theoretical concept that neurotic disorders in adults are the result of unresolved aspects of the infantile neurosis. As the concept of infantile neurosis is derived from psychoanalysis, this theory implicitly argues that adequate treatment of a patient with a neurosis is psychoanalysis or psychoanalytic psychotherapy-a therapy designed to treat the adverse effect of the unresolved infantile neurosis in adulthood. Unfortunately, this theory of causation and treatment is not supported by any agreed-on, replicable empirical data. Eventually, diagnostic systems derived from theories alone do not survive (Weissman, 1999).

The second approach taken with diagnostic systems uses empirical data to classify and cluster behavioral observations of a patient into descriptive diagnostic statements with distinct labels. These diagnostic descriptions can then be observed in individuals within large populations. At present, psychiatry uses the diagnostic system developed by the American Psychiatric Association (APA). This system is not based on a stated theory, but it frequently implies a biologic causality for observed behavior. The system is based on classifying varying behaviors or symptoms into descriptive clusters and then giving a name to each cluster. In addition to using behaviors or symptoms, the system uses signs and the duration of certain behaviors in determining diagnoses. Diagnoses are standardized by using a number of strategies. Some diagnoses are seen as being consistent over time; others describe disorders of short duration. As noted earlier, each descriptive statement (diagnosis) was field-tested to ensure that each cluster would be given essentially the same label by reviewers.

Fueled by the diagnostic system of the APA, psychiatrists around the world have made significant advances in understanding certain mental disorders and in developing treatments for them. Effective, clear, replicable, and agreed-on diagnosis has allowed psychiatric researchers to advance their knowledge of the etiology and treatment of some mental disorders. These advances have predominantly been in the areas of affective and psychotic disorders, where there is overwhelming evidence of brain dysfunction. In areas of behavioral dysfunction not clearly linked to brain dysfunction, the fourth edition of the DSM (DSM-IV; APA, 1994) has been less helpful in aiding research. Of potential significance to this discussion is the fact that the CD diagnosis had one of the highest reliability scores in DSM-IV field-testing.