Would broadening the diagnostic criteria for bipolar disorder do more harm than good? Implications from longitudinal studies of subthreshold conditions.

BACKGROUND: The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), is a categorical system that provides descriptive diagnostic criteria for psychiatric syndromes. These syndrome descriptions are imperfect representations of an underlying behavioral, psychological, or biological dysfunction; thus, the criteria could be conceptualized as a type of test for the etiologically defined illnesses. Accordingly, as with any other diagnostic test, diagnoses based on DSM-IV criteria produce some false positive and some false negative results. That is, some patients who meet the criteria will not have the illness (ie, false positives), and some who do not meet the criteria because their symptoms fall below the diagnostic threshold will have the illness and incorrectly not receive the diagnosis (ie, false negatives). In this context, I consider the controversy over whether the diagnostic threshold for bipolar disorder should be lowered.
METHOD: Longitudinal studies of the prognostic significance of subthreshold bipolar disorder are considered.
RESULTS: Subthreshold bipolarity is a risk factor for the future emergence of bipolar disorder, but the majority of individuals with subthreshold bipolarity do not develop a future manic or hypomanic episode.
CONCLUSIONS: The diagnostic threshold for bipolar disorder should not be lowered for 4 reasons: (1) the results of longitudinal studies suggest that lowering the diagnostic threshold for bipolar disorder will result in a greater increase in false positive than true positive diagnoses; (2) there are no controlled studies demonstrating the efficacy of mood stabilizers in treating subthreshold bipolar disorder; (3) if a false negative diagnosis occurs and bipolar disorder is underdiagnosed, diagnosis and treatment can be changed when a manic/hypomanic episode emerges; and (4) if bipolar disorder is overdiagnosed and patients are inappropriately prescribed a mood stabilizer, the absence of a future manic/hypomanic episode would incorrectly be considered evidence of the efficacy of treatment, and the unnecessary medications that might cause medically significant side effects would not be discontinued. © Copyright 2012 Physicians Postgraduate Press, Inc.