Research paperImpact of predominant polarity on long-term outcome in bipolar disorder: A 7-year longitudinal cohort study
Introduction
Bipolar Disorder (BD) is a severe and recurrent psychiatric disorder identified by periodic episodes of depressive and manic symptomatology. It affects approximately 2.4% of the population (Merikangas et al., 2011) and is associated with the highest suicide rate among psychiatric disorders (Goldstein et al., 2012).
The BD diagnosis is often accompanied by specifiers intended to further detail the course of the disorder and provide predictive tools for treatment. Specifiers included in the DSM-5 (American Psychiatric Association, 2013) are divided into two categories: 1) specifiers defining the current episode, which include the presence of psychotic, mixed, melancholic, atypical and catatonic features, and 2) specifiers defining recurrent episodes (course of the disorder), which include rapid cycling, peripartum onset and seasonal patterns (American Psychiatric Association, 2013). Recent studies have suggested Predominant Polarity (PP) as an important course specifier of the disorder, establishing distinct groups of patients and providing another tool for tailored treatment (Carvalho et al., 2015; Colom et al., 2006, Rosa et al., 2008). PP consists of three categories: 1) Manic Predominant Polarity (MPP), 2) Depressive Predominant Polarity (DPP), and 3) Indefinite Predominant Polarity (IPP). There are currently two established definitions of the specifier (Colom et al., 2015): the Barcelona proposal (Colom et al., 2006), which requires participants to present at least two-thirds (2/3) of lifetime episodes of one polarity in order to be included into either the MPP or the DPP categories, and the Harvard proposal (Baldessarini et al., 2012), which instead requires participants to present a simple majority of episodes of one polarity for inclusion in either category.
PP has been associated with various clinical variables correlated with the course of the disorder. DPP has been associated with higher numbers of suicide attempts, depressive onset and comorbid anxiety disorders (Azorin et al., 2015, Colom et al., 2006). MPP has been associated to higher rates of substance abuse, psychotic symptoms, and hospitalizations, earlier onset of symptoms, and manic/psychotic onset (Carvalho et al., 2014, Popovic et al., 2014). A systematic review of 16 articles, conducted by García-Jiménez and colleagues (García-Jiménez et al., 2017), found MPP to be associated with a manic onset, drug consumption prior to onset, and a better response to antipsychotics and mood stabilizers. The same study also found DPP to be associated with a depressive onset, more relapses, prolonged episodes, greater suicide risk, and a later diagnosis of BD. PP has also been associated with therapeutic regiments. Recent studies have associated PP to the Polarity Index (PI), which aims to provide a guide to clinicians for choosing pharmacological treatments by characterizing medications as either having anti-manic (>1) or anti-depressant (<1) prophylactic properties (Gnanavel, 2015, Popovic et al., 2014). MPP patients are more often treated and present better responses to positive PI medications (anti-manic stabilization packages) while DPP are more often treated with medications presenting a negative PI (anti-depressive stabilizations packages) (Popovic et al., 2012, Carvalho et al., 2015). Finally, a recent study found PP to be associated with cognitive impairments, in which MPP patients demonstrated significantly poorer performances in various neuropsychological domains when compared to DPP and IPP patients, and healthy controls (Belizario et al., 2017). However, most published studies investigating PP are retrospective, often employing a cross-sectional design unable to determine causality.
The present study´s primary focus is on associations between PP and longitudinal clinical variables, hypothesizing that DPP patients should present significantly higher numbers of total episodes and suicide attempts, and MPP patients should present higher numbers of hospitalizations and psychotic symptoms throughout the 7-year follow-up. The secondary hypotheses, concerning associations between PP and baseline clinical and demographic variables, investigated whether MPP is associated to BD type 1, comorbid substance abuse/dependence, and an earlier onset of symptoms, and also tested whether DPP is associated to BD type 2, a delayed diagnosis of BD, and comorbid anxiety disorders. Lastly, although we found no literature regarding IPP patients, the study hypothesized that this subgroup should present results positioned in between MPP and DPP patients´ results.
Section snippets
Methods and materials
Participants were recruited from the outpatient clinic of the Bipolar Disorder Research Program (PROMAN) at the Institute of Psychiatry of the Hospital das Clinicas of the University of São Paulo Medical School. Inclusion criteria required participants to be between 18 and 60 years of age, reside in the city of São Paulo and present a diagnosis of BD, type 1 or 2, accordingly to the DSM-IV-TR´s requirements. Patients presenting schizoaffective disorder were excluded from the study.
We followed
Results
The study included 87 participants in total, 23 males and 64 females (27% and 73% respectively), with an average age of 49.19 (SD = 9.67) years old and 12.31 (SD = 3.67) years of schooling at baseline. The sample was divided into 3 groups: (1) 25 MPP patients, (2) 42 DPP patients, and (3) 20 IPP patients. Univariate analysis of demographic variables (Table 1) revealed significant differences between groups only for gender (p = 0.026), with females being more prevalent in the DPP group. Age (p
Discussion
The results were supportive, in part, of the primary hypotheses, which correctly predicted, based on retrospective and cross-sectional studies, a higher number of hospitalizations and psychotic symptoms in MPP patients. Number of suicide attempts were also significantly more prevalent in MPP patients. Moreover, the number of total episodes was slightly more prevalent in MPP patients although not statistically significant. Previous studies are congruent with these findings regarding the higher
Contributors
GOB and BL designed the study. GOB and MS collected the data. GOB conducted the statistical analysis and GOB, MS and BL drafted the manuscript. All authors have contributed to this study. All authors read and approved the final manuscript.
Role of the funding source
This study was supported in part by a generous donation received from Suzana and Carlos Melzer. BL is supported by Brazilian federal research grants and scholarships from CNPq. GB and MS received no other funding to conduct this study.
Conflict of interest
All authors declare that they have no conflict of interests.
Acknowledgements
We thank Pedro Fernandes Makhoul and Julia Levine for comments that greatly improved the manuscript and for proof reading the article.
References (17)
- et al.
Predominant polarity in bipolar disorders: further evidence for the role of affective temperaments
J. Affect. Disorders
(2015) - et al.
Predominant polarity as a course specifier for bipolar disorder: a systematic review
J. Affect. Disorders
(2014) - et al.
Clinical and therapeutic implications of predominant polarity in bipolar disorder
J. Affect. Disorders
(2006) - et al.
Clinical correlates of first-episode polarity in bipolar disorder
Comprehensive Psychiatry
(2006) - et al.
Polarity index of pharmacological agents used for maintenance treatment of bipolar disorder
Eur. Neuropsychopharmacol.
(2012) - et al.
Predominant polarity in bipolar disorder: diagnostic implications
J. Affect. Disorders
(2008) Diagnostic and Statistical Manual of Mental Disorders
(2013)- et al.
Predominant recurrence polarity among 928 adult international bipolar I disorder patients
Acta Psychiatrica Scandinavica
(2012)
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