Bipolar II with and without cyclothymic temperament: “dark” and “sunny” expressions of soft bipolarity

Abstract

Background: In the present report deriving from the French national multi-site EPIDEP study, we focus on the characteristics of Bipolar II (BP-II), divided on the basis of cyclothymic temperament (CT). In our companion article (Hantouche et al., 2003, this issue), we found that this temperament in its self-rated version correlated significantly with hypomanic behavior of a risk-taking nature. Our aim in the present analyses is to further test the hypothesis that such patients—assigned to CT on the basis of clinical interview—represent a more “unstable” variant of BP-II. Methods: From a total major depressive population of 537 psychiatric patients, 493 were re-examined on average a month later; after excluding 256 DSM-IV MDD and 41 with history of mania, the remaining 196 were placed in the BP-II spectrum. As mounting international evidence indicates that hypomania associated with antidepressants belongs to this spectrum, such association per se did not constitute a ground for exclusion. CT was assessed by clinicians using a semi-structured interview based on Akiskal and Mallya (1987) in its French version; as two files did not contain full interview data on CT, the critical clinical variable in the present analyses, this left us with an analysis sample of 194 BP-II. Socio-demographic, psychometric, clinical, familial and historical parameters were compared between BP-II subdivided by CT. Psychometric measures included self-rated CT and hypomania scales, as well as Hamilton and Rosenthal scales for depression. Results: BP-II cases categorically assigned to CT (n=74) versus those without CT (n=120), were differentiated as follows: (1) younger age at onset (P=0.005) and age at seeking help (P=0.05); (2) higher scores on HAM-D (P=0.03) and Rosenthal (atypical depressive) scale (P=0.007); (3) longer delay between onset of illness and recognition of bipolarity (P=0.0002); (4) higher rate of psychiatric comorbidity (P=0.04); (5) different profiles on axis II (i.e., more histrionic, passive-aggressive and less obsessive-compulsive personality disorders). Family history for depressive and bipolar disorders did not significantly distinguish the two groups; however, chronic affective syndromes were significantly higher in BP-II with CT. Finally, cyclothymic BP-II scored significantly much higher on irritable-risk-taking than “classic” driven-euphoric items of hypomania. Conclusion: Depressions arising from a cyclothymic temperament—even when meeting full criteria for hypomania—are likely to be misdiagnosed as personality disorders. Their high familial load for affective disorders (including that for bipolar disorder) validate the bipolar nature of these “cyclothymic depressions.” Our data support their inclusion as a more “unstable” variant of BP-II, which we have elsewhere termed “BP-II 1/2.” These patients can best be characterized as the “darker” expression of the more prototypical “sunny” BP-II phenotype. Coupled with the data from our companion paper (Hantouche et al., 2003, this issue), the present findings indicate that screening for cyclothymia in major depressive patients represents a viable approach for detecting a bipolar subtype that could otherwise be mistaken for an erratic personality disorder. Overall, our findings support recent international consensus in favoring the diagnosis of cyclothymic and bipolar II disorders over erratic and borderline personality disorders when criteria for both sets of disorders are concurrently met.

Introduction

It is generally accepted that the cyclothymic temperament (CT) is the precursor of bipolar, especially bipolar II (BP-II) disorder (Akiskal et al., 1977, Depue et al., 1981, Akiskal, 2001). However, in a review article, Howland and Thase (1993) opined that only some forms of cyclothymia are associated with bipolar disorder, and that the condition is clinically heterogeneous.

Historically, Kraepelin (1921 [English translation]) was among the first to suggest that CT—which he actually termed “predisposition” rather than “temperament”—represents a subclinical condition preceding the more severe circular states of mania and melancholia. Kretschmer (1936), too, used the term “cyclothymia” as the constitutional basis for periodic depression and hypomania. The classical paper on cyclothymia as an ambulatory form of manic-depression was written by the German psychiatrist Hecker (see English translation in this issue (Koukopoulos, 2003); he was a disciple of Kahlbaum who had coined the term “cyclothymia” (“zyklothymie”, Kahlbum, 1882). A rich French literature (see, for instance, Ritti, 1880, Khan, 1909)—insufficiently appreciated today by anglophone and germanophone psychiatrists—has documented the short-lived repeated excitement in the lives of these ambulatory depressives, thereby justifying their inclusion within the larger sphere of manic-depressive psychosis as the more classical illness was called in those days. Given the lifelong nature of the subthreshold affective instability, CT is often misdiagnosed as an erratic personality disorder (Akiskal et al., 1977, Akiskal et al., 1979). As a result, major depressive episodes with a cyclothymic base might be erroneously assigned to the realm of borderline personality disorder (Akiskal, 1981; Levitt et al., 1990). To avoid such diagnostic pitfalls, one of us (Akiskal, 1994) has suggested the rubric of “cyclothymic depression” to highlight the bipolar nature of these patients.

In contemporary times, the link of CT to bipolar disorder was validated by the author’s team (Akiskal et al., 1977) in a clinical population, and Depue et al. (1981) in a college population. Epidemiologic research has demonstrated a population prevalence of 6.3% (Placidi et al., 1998) with excellent discriminating validity from other temperament constructs (Akiskal et al., 1998). Despite the classical tradition and contemporary research, CT is rarely used today as a diagnostic rubric by clinicians and researchers (Brieger and Marneros, 1997).

In order to further clarify the question of a “cyclothymic–BP-II continuum” (Akiskal et al., 1979), we report herein data from the French multi-center EPIDEP study. We focus on a systematic comparison between BP-II with and without CT.