Validating the bipolar spectrum in the French National EPIDEP Study: overview of the phenomenology and relative prevalence of its clinical prototypes

Abstract

Background: Few studies have been undertaken to ascertain the feasibility of using the bipolar (BP) spectrum in clinical practice. The only systematic national study is the French EPIDEP Study of consecutive inpatients and outpatients presenting with major depressive episodes (MDE). The protocol was developed in 1994 and implemented in 1995; publication of its first data began in 1998. This report provides the complete data set of the EPIDEP.

Methods: Forty-eight psychiatrists, practicing in 15 sites in four regions of France (Paris, Besançon, Bordeaux and Marseille), were all trained on a common protocol based on DSM-IV criteria for MDE (n=537) subdivided into BP-I (history of mania), BP-II (history of hypomania), as well as extended definitions of the "softer spectrum" beyond BP-I and BP-II. Measures tapping into this spectrum included the Hypomania Checklist (HCA), the cyclothymic (CT), depressive (DT) and hyperthymic (HT) temperament scales. These measures and course permitted post-hoc assignment of MDE in the bipolar spectrum, based in part on the Akiskal, H.S., Pinto, O., 1999. [The evolving bipolar spectrum: Prototypes I, II, III, IV. Psychiatr. Clin. North Am. 22, 517-534] proposal: depression with history of spontaneous hypomanic episodes (DSM-IV, BP-II), cyclothymic depressions (BP-II(1/2)), antidepressant-associated hypomania (BP-III) and hyperthymic depressions (BP-IV). <<Strict UP>> was thereby limited to an exclusion diagnosis for the remainder of MDE.

Limitation: In the clinical setting, psychiatrists cannot be entirely blind to the observations in the various clinical evaluations and instruments. However, the systematic multisite collection of such data tended to minimize any such biases.

Results: After excluding patients lost to follow-up, among 493 presenting with MDE with complete data files, the BP-II rate was estimated at index at 20%; 1 month later, systematic probing for hypomania doubled the rate of BP-II to 39%. The comparison between BP-II and UP showed differential phenomenology, such as hypersomnia, increased psychomotor activation, guilt feelings and suicidal thoughts in BP-II. Related data demonstrated the importance of CT in further qualifying of MDE to define a distinct, more severe ("darker") BP-II(1/2) variant of BP-II. Moreover, BP-III, arising from DT and associated with antidepressants, emerged as a valid soft bipolar variant on the basis of the phenomenology of hypomania and bipolar family history. Finally, we found preliminary evidence for the inclusion of BP-IV into the bipolar spectrum, its total hypomania score falling intermediate between BP-II and strict UP. Using this broader diagnostic framework, the bipolar spectrum (the combined "hard" BP-I phenotype, BP-II and the soft spectrum) accounted for 65% of MDE.

Conclusion: The EPIDEP study achieved its objectives by demonstrating the feasibility of identifying the bipolar spectrum at a national level, and refining its phenomenology through rigorous clinical characterization and validation of bipolar spectrum subtypes, including MDE with brief hypomanias, cyclothymia and hyperthymia. The spectrum accounted for two out of three MDE, making "strict UP" less prevalent than BP as redefined herein. Our findings were anticipated by Falret, who in 1854 had predicted that many melancholic patients in the community would 1 day be classified in his circular group. We also confirmed Baillarger's observation in the same year that episodes (in this study, hypomanic episodes) could last as short as 2 days. Our findings deriving from a systematic French national database a century and a half later invite major shifts in clinical and public health services, as well as in the future conduct of psychopharmacologic trials. In this respect, the systematic training of clinicians in four regions of France represents a national resource for affective disorders and can serve as a model to effect change in diagnostic practice in other countries.