Broadening bipolar disorder − by design or by accident?

The discussion by Strakowski et al makes explicit a state of affairs that has not often been clearly articulated. That is, there is a tension between narrow and broad definitions of bipolar disorder in adults just as there is in children and adolescents. However, while the concept of a bipolar spectrum from cyclothymia to schizoaffective mania is well recognized, the real expansion of the bipolar disorder diagnosis may have been the unintended consequence of certain DSM decisions – not a trivial consideration given that we are on the cusp of a new DSM. In the following paragraphs, I submit some hypotheses. First, the concept of an episode of mania was not defined well in the DSM-III. A distinct period was defined as “at least a week”, but no offset was required to delineate an episode, nor was there a requirement that the episode be different from one’s “usual self”. The DSM-III-R muddied the waters even further by eliminating duration criteria and just requiring “a distinct period”. As we see with much of the childhood bipolar disorders research, the onset of a manic episode is said to have begun in early child-hood and has either never stopped 1,2 or has lasted for years. It is difficult to consider an episode as something that has characterized one’s entire life. On the other end of the duration spectrum, ultra-rapid cycles, and ultradian cycles, i.e. distinct periods that last minutes to hours, are very difficult to distinguish from mood lability and temper tantrums, certainly in children and probably adults, too. The DSM-5 committee appears to have recognized this misunderstanding and, at least according to the DSM-5 website, is proposing changes in “episode” definition. Another DSM change that may have altered bipolar disorder prevalence is the elimination of “irritability” as a symptom of depression because mania was felt to be a better home for that symptom. It is not surprising that the frequency of “mixed episodes” increased dramatically after DSM-III-R. In the DSM-III, the criterion for a major depressive episode was “dysphoric mood” which was characterized by, among other things, irritability. Childhood depression was initially studied with interviews that incorporated irritability in depression. For instance, the 1983 version of the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) stated “Some children will deny feeling ‘sad’ and only report being ‘bad’. If during a depressed period patient is also irritable this should be counted as dysphoric mood and rated as such” 3. When it came time to re-examine criteria, the DSM-IV child mood subcommittee and I (I was chair) insisted that irritability be kept in the definition of childhood depression, since there was no evidence to eliminate it. What has evolved in recent research suggests it was a wise decision. Irritability in a number of studies predicts a depressed and anxious outcome, not a bipolar outcome 4,5,6. Another downstream result of DSM criteria is the assessment approach that has arisen to diagnose children and adults with mood disorders. Although interviews all do a decent job of assessing a review of systems, none of them does a very good job of ascertaining history 7. Some interviews obtain a time line but those data are not entered. It is, therefore, impossible to review anyone’s interview protocol and reconstruct the history of any given patient. We cannot tell whether the subject of the interview has “classic” or narrowly defined manic-depressive illness or more broadly diagnosed bipolar disorder. In child studies, furthermore, all sorts of other assessment issues occur that can broaden the diagnosis. The “OR” rule accepts as positive any informant’s symptom endorsement (parent OR child), so more children will have mania than if parent/child agreement is required. Changing the meanings of elation and grandiosity will get a different sample than if requiring adult definitions. Severe mood dysregulation was designed to capture irritable, explosive youth with “broad phenotype” mania and contrast it with narrow phenotype 8. However, those who characterize children with mania as very irritable and explosive do not consider them to have the “broad phenotype”. As consumers, we never know whether the sample being described in any given study is “narrowly” or “broadly” diagnosed. The implications of understanding study results are considerable. Findings on age of onset of bipolar disorder, a marker that may have genetic implications, differ depending on one’s conceptualization. Bipolar disorder traditionally has an age of onset in late adolescence and young adulthood 9. However, those findings are probably based on “classic” bipolar disorder. The STEP-BD data 10 report subjects with onsets in early childhood. Perhaps subjects in this large sample are “broadly diagnosed”, which is also one of the reasons they do so poorly in treatment. They may well be emotionally dysregulated people who “meet criteria” but do not have “classic” bipolar disorder. They are similarly impaired but should be identified as separate from the narrow phenotype. As Strakowski et al point out, the research question of whether and when a broad vs. narrow concept of bipolar disorder has traction is important. The tragedy is that there is no way to resolve the question because of how we collect and how we report the data.