Research reportPredominant polarity and temperament in bipolar and unipolar affective 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
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2019, Journal of Affective DisordersCitation Excerpt :009, respectively). Mazzarini et al., (2009) studied the frequency and duration of hospitalization and did not find any significant difference between the MPP and DPP groups; however, these authors reported that the duration of hospitalization in months was longer for DPP than unipolar patients (5.9 vs 1.8, p = 0.01). The PI for the drugs used in maintenance therapy for bipolar disorder, a measure of how much antidepressant versus antimanic a drug is, when tested in the context for specialized setting for evidence-based treatment for patients with BD (Vieta, 2011) has shown that the treatment of patients with MPP was oriented mostly toward mania prevention, as evidenced by higher PI, while treatment of DPP patients was characterized by lower mean PI, thus directed toward preventing depression (Popovic et al., 2014).