Research report
Predominant polarity and temperament in bipolar and unipolar affective disorders

https://doi.org/10.1016/j.jad.2009.03.016Get rights and content

Abstract

Introduction

Recently, the concept of predominant polarity (two-thirds of episodes belonging to a single pole of the illness) has been introduced to further characterise subtypes of bipolar disorders. This concept has been proven to have diagnostic and therapeutic implications, but little is known on the underlying psychopathology and temperaments. With this study, we aimed to further validate the concept and explore its relationships with temperament.

Methods

This study enrolled 143 patients with bipolar or unipolar disorder. We analysed predominant polarity in the sample of bipolar I patients (N = 124), focussing on those who showed a clear predominance for one or the other polarity, and distinguishing manic/hypomanic (MP) from depressive polarity (DP), and a unipolar major depression (UP) group (N = 19),. We also assessed temperament by means of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A).

Results

Over 55% of the bipolar I sample fulfilled predominant polarity criteria, with two-thirds of those meeting criteria for MP and one third for DP. MP and DP were similar in scoring higher than UP on the hyperthymic/cyclothymic scales of the TEMPS-A; the UP group scored higher on the anxious/depressive scales.

Discussion

Our results show that both bipolar I MP and DP subgroups are temperamentally similar and different from UP. Depression in DP bipolar I patients should be viewed as the overlap of depression on a hyperthymic/cyclothymic temperament. These findings confirm the value of the predominant polarity concept as well as the importance of temperaments to separate bipolar from unipolar disorders.

Introduction

Bipolar (BP) and Major Depressive Disorder (MDD, UP) are considered by the DSM-IV-TR (American Psychiatric Association, 2000) and ICD-10 (WHO, 1992), the two most commonly used nosotaxies, as rather different nosographic categories that share common symptoms. Inspired by Kraepelin's model (1921), Akiskal and others considered all mood disorders as part of the same continuum, the so called “bipolar spectrum” (Goodwin and Jamison, 1990, Akiskal and Pinto, 1999, Ghaemi et al., 2002). The concept of bipolar spectrum would include temperaments, mild, subclinical presentations of mood disorders, and overt bipolar I disorder and schizobipolar; it would encompass major and minor depression, dysthymia, cyclothymic disorder and bipolar II disorder (Akiskal and Pinto, 1999, Akiskal et al., 2000, Akiskal, 2002).

The term temperament was proposed by Emil Kraepelin as “forma fruste” of Manic Depressive Insanity (1921) and, according to Akiskal's view, refers to subaffective trait expressions representing the earliest subclinical phenotypes of affective disorders, which persist as the subthreshold interepisodic phase of these disorders (Akiskal and Akiskal, 1992, Akiskal and Akiskal, 2005). Some authors have found an association between s allele of serotonin transporter gene and depressive temperament, suggesting that affective temperaments could represent behavioural endophenotypes (Gonda et al., 2006). Besides the importance of temperament in increasing the predisposition for developing mood disorders (Henry et al., 1999), it is noteworthy that it is one of the main variables accounting for some features in the clinical evolution of mood disorders such as polarity of episodes.

Recent research postulated that the predominance of a certain mood polarity is a robust outcome predictor with major clinical and therapeutic implications in the long-term (Colom et al., 2006, Rosa et al., 2008, Vieta et al., 2009), confirming earlier proposals (Angst, 1978, Quitkin et al., 1986, Judd et al., 2003), and the need to include this course specifier in DSM-V (Vieta and Phillips, 2007, Ghaemi et al., 2008, Colom and Vieta, 2009).

It has been reported that between 45% and 70% of all bipolar patients fulfil criteria for a certain “predominant polarity”; this means that at least two-thirds of episodes are restricted to a single pole of the illness (Colom et al., 2006).

Amongst those patients with a defined predominant polarity, around 60% have a depressive predominant polarity (DP) and about 40% have a manic predominant polarity (MP) (which also includes hypomanic episodes, but not mixed (Colom et al., 2006, Rosa et al., 2008).

There are clinical differences between patients with different predominant polarity. Depressive predominant polarity is strongly associated with depressive onset and is more common amongst bipolar II patients, while manic predominant polarity is associated with manic onset, early age of onset, and substance abuse (Colom et al., 2006, Daban et al., 2006 Rosa et al., 2008).

We compared demographic, clinical and temperamental variables amongst the three mentioned groups with the aim to clarify whether predominantly depressed bipolar patients tend to cluster with predominantly (hypo)manic bipolar or, on the contrary, are more similar to unipolar depressive patients.

To the best of our knowledge, this is the first study comparing bipolar patients with depressive (DP) or manic/hypomanic predominant polarity (MP) with unipolar patients (UP).

Section snippets

Methods

We included consecutively enrolled inpatients with bipolar I or II disorder (N = 124) and with unipolar major depression (N = 19); diagnoses were made according to the DSM-IV criteria and confirmed through the Structured Clinical Interview (SCID-I and SCID-II) for DSM-IV-TR (First et al., 1996, First et al., 1997). All patients were hospitalized between January and June 2008 at the psychiatric Unit of Sant'Andrea Hospital (Rome, Italy) — whose Ethical Committee approved the study — and provided

Statistical analysis

Groups (DP, MP and Unipolar Depression [UP]) were compared regarding clinical and sociodemographic variables. We used the Chi-square test to compare categorical data. Subsequently, we performed a Chi-square head-to-head analysis. Dimensional group differences were tested using one-way analysis of variance (ANOVA 1-way), followed by Tukey's post hoc comparison, when significant main effects were present. Significance was set at p  0.0014 (p  0.05 with Bonferroni correction for thirty-four

Results

The study enrolled 143 patients, 124 of whom had bipolar disorder. Predominant polarity criteria were fulfilled by 69 out of 124 bipolar patients (55.7%). Hence, fifty five (44.3%) out of 124 subjects with bipolar disorder were excluded from further analysis because they did not present any specific predominant polarity according to our definition. The final sample (N = 88) included sixty-nine (78.4%) patients with bipolar disorder I and nineteen (21.6%) patients with UP depression. Within the

Discussion

This study confirms previous findings regarding differences in clinical and demographical characteristics of bipolar patients according to their predominant polarity (Colom et al., 2006, Rosa et al., 2008). Importantly, this is a completely independent sample of the Catalan/Spanish one (Colom et al., 2006) and the Brazilian one (Rosa et al., 2008). In agreement with those previous studies, we found that more than half of all of bipolar patients (55.7%) in our sample satisfied criteria for any

Role of funding source

Funding for this study was provided by CIBERSAM, which had no further role in study design, the collection, analysis, and interpretation of data, the writing of the report, or in the decision to submit the paper for publication.

Conflict of interest

Disclosure of potential conflict of interest:

Lorenzo Mazzarini has no conflict of interests.

Isabella Pacchiarotti has no conflict of interests.

Giorgio D. Kotzalidis has no conflict of interests.

C. Mar Bonnin has no conflict of interests.

Adriane R. Rosa has no conflict of interests.

Jose Sanchez-Moreno has no conflict of interests.

Pietro De Rossi has no conflict of interests.

Gabriele Sani has no conflict of interests.

Livia Sanna has no conflict of interests.

Nicoletta Girardi has no conflict of

References (41)

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