Bipolar II with and without cyclothymic temperament: "dark" and "sunny" expressions of soft bipolarity.

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., 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 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.