Elsevier

Journal of Affective Disorders

Volume 241, 1 December 2018, Pages 37-40
Journal of Affective Disorders

Research paper
Impact of predominant polarity on long-term outcome in bipolar disorder: A 7-year longitudinal cohort study

https://doi.org/10.1016/j.jad.2018.07.086Get rights and content

Highlights

  • Predominant Polarity (PP) may be an important specifier of Bipolar Disorder (BD).

  • Number of suicide attempts, hospitalizations, and psychotic symptoms were significantly more prevalent in MPP patients throughout the 7-year follow-up.

  • Overall, MPP was significantly associated with longitudinal variables indicative of a worse outcome.

  • Lastly, baseline PP was associated with 7-year observed PP, suggesting that patients tend to remain within the same PP throughout the course of the disorder.

Abstract

Introduction

Recent studies suggest that Predominant Polarity (PP) may be an important specifier of Bipolar Disorder (BD), establishing distinct groups of patients and providing a potential tool for tailored treatment. PP has been associated to various clinical variables present in the course of the disorder, including deficits in cognitive functioning, suicide attempts, hospitalizations and response to pharmacological treatment. However, most published studies are retrospective and cross-sectional, frequently relying on patients´ ability to recall past information, which may often be inaccurate.

Methods

Participants were recruited from the outpatient clinic of the Bipolar Disorder Research Program at the Institute of Psychiatry of the University of São Paulo. Baseline clinical and demographic variables were collected using a semi-structured questionnaire and the SCID-CV. Longitudinal data were collected through medical records, mood charts, and mood symptom scales conducted throughout a 7-year follow-up period.

Results

Manic Predominant Polarity (MPP) was associated with a significantly higher number of hospitalizations, suicide attempts, and episodes with psychotic symptoms throughout the 7-year observed period in comparison to Depressive Predominant Polarity (DPP) and Indefinite Predominant Polarity (IPP) patients. Moreover, baseline PP was significantly associated with 7-year PP, with 67% of patients maintaining their PP both at baseline and after the 7-year follow-up period.

Limitations

The present study is limited due to the statistically small sample size, although, to our knowledge, it is the largest longitudinal study conducted in this topic, and the unequally distributed frequency of patients´ visitations, which may have created intervals of unobserved periods within the follow-up period.

Discussion

The results revealed PP to be an important specifier for predicting the course of the disorder. Overall, MPP was significantly associated with variables indicative of a worse outcome, suggesting that greater attention to preventive treatment should be addressed to this subgroup. Lastly, baseline PP was significantly associated with 7-year observed PP, suggesting that patients tend to remain within the same PP throughout the course of the disorder.

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)

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