Should bipolar disorder be viewed as manic disorder? Implications for bipolar depression

Bipolar Depression: A Historical Perspective of the Current Concept, with a Focus on Future Research

The aim of this narrative review is to trace the origin of the concept of bipolar depression and to expose some of its limitations. Bipolar depression is a broad clinical construct including experiences ranging from traditional melancholic and psychotic episodes ascribed to "manic-depressive insanity," to another heterogeneous group of depressive episodes originally described in the context of binary models of unipolar depression (e.g., psychogenic depression, neurotic depression). None of the available empirical evidence suggests, however, that these subsets of "bipolar" depression are equivalent in terms of clinical course, disability, family aggregation, and response to treatment, among other relevant diagnostic validators. Therefore, the validity of the current concept of bipolar depression should be a matter of concern. Here, we discuss some of the potential limitations that this broad construct might entail in terms of pathophysiological, clinical, and therapeutic aspects. Finally, we propose a clinical research program for bipolar depression in order to delimit diagnostic entities based on empirical data, with subsequent validation by laboratory or neuroimaging biomarkers. This process will then aid in the development of more specific treatments.

The dual-system theory of bipolar spectrum disorders: A meta-analysis

Bipolar spectrum disorders are characterized by alternating intervals of extreme positive and negative affect. We performed a meta-analysis to test the hypothesis that such disorders would be related to dysregulated reinforcement sensitivity. First, we reviewed 23 studies that reported the correlation between self-report measures of (hypo)manic personality and measures of reinforcement sensitivity. A large relationship was found between (hypo)manic personality and BAS sensitivity (g = .74), but not with BIS sensitivity (g = -.08). This stands in contrast to self-reported depression which has a small, negative relationship with BAS sensitivity and a large positive one with BIS sensitivity (Katz et al., 2020). Next, we reviewed 33 studies that compared reinforcement sensitivity between euthymic, bipolar participants and healthy controls. There, bipolar disorder had a small, positive relationship with BAS sensitivity (g = .20) and a medium, positive relationship with BIS sensitivity (g = .64). These findings support a dualsystem theory of bipolar disorders, wherein BAS sensitivity is more closely related to mania and BIS sensitivity more closely to bipolar depression. Bipolar disorders show diatheses for both states with euthymic participants being BAS- and BIS- hypersensitive. Implications for further theory and research practice are expounded upon in the discussion.

The structure of mania: An overview of factorial analysis studies

Background.

Operational definitions of mania are based on expert consensus rather than empirical data. The aim of this study is to identify the key domains of mania, as well as the relevance of the different signs and symptoms of this clinical construct.

Methods.

A review of latent factor models studies in manic patients was performed. Before extraction, a harmonization of signs and symptoms of mania and depression was performed in order to reduce the variability between individual studies.

Results.

We identified 12 studies fulfilling the inclusion criteria and comprising 3039 subjects. Hyperactivity was the clinical item that most likely appeared in the first factor, usually covariating with other core features of mania, such as increased speech, thought disorder, and elevated mood. Depressive–anxious features and irritability–aggressive behavior constituted two other salient dimensions of mania. Altered sleep was frequently an isolated factor, while psychosis appeared related to grandiosity, lack of insight and poor judgment.

Conclusions.

Our results confirm the multidimensional nature of mania. Hyperactivity, increased speech, and thought disorder appear as core features of the clinical construct. The mood experience could be heterogeneous, depending on the co-occurrence of euphoric (elevated mood) and dysphoric (irritability and depressive mood) emotions of varying intensity. Results are also discussed regarding their relationship with other constitutive elements of bipolar disorder, such as mixed and depressive states.

Implicit and explicit self-associations in bipolar disorder: a comparison with healthy controls and unipolar depressive disorder

According to cognitive theory, negative self-schemas are involved in the occurrence of depression. Whereas implicit depressive self-associations have been found in unipolar depression, it is unknown whether impaired associations with regard to the self are also involved in Bipolar Disorder (BD). This study investigated whether a bias in self-associations is a characteristic of bipolar disorder and whether discrepancies between implicit and explicit self-evaluations may be relevant for understanding bipolar psychopathology. Implicit and explicit self-associations were assessed in patients with BD (n=99), in patients with depressive disorder (n=1236), and healthy controls (n=387). Analyses of variance and correlation analyses were used to compare bipolar patients to controls and unipolar patients on implicit self-associations and the discrepancy between implicit and explicit self-associations. Similar to unipolar patients, patients with BD showed stronger implicit depressive self-associations than controls. Specifically for bipolar patients there was no significant correlation between implicit and explicit depressive self-associations. In a similar vein, discrepancies between implicit and explicit self-associations were relatively pronounced in symptomatic bipolar patients as compared to both healthy controls and unipolar depressed patients. Thus automatic depressive self-associations were characteristic for all mood disorders whereas a lack of concordance between implicit and explicit self-associations was specific for BD.

Rejection Sensitivity is Associated with Quality of Life, Psychosocial Outcome, and the Course of Depression in Euthymic Patients with Bipolar I Disorder

Rejection sensitivity has been found to predict the course of unipolar depression as well as key outcomes, but has not yet been considered within bipolar disorder. The present study investigated the effects of rejection sensitivity on outcome in bipolar disorder. Fifty-three participants diagnosed with bipolar I disorder in remission using the Structured Clinical Interview for DSM-IV were compared to 44 controls with no history of mood disorder. A subset of 38 bipolar participants completed follow-up interviews using standard symptom severity measures at 6 months. People with bipolar I disorder reported higher rejection sensitivity scores than did controls. Within the bipolar sample, rejection sensitivity at baseline predicted increases in depression, but not mania, over the following 6 months; heightened rejection sensitivity was also correlated with poorer quality of life, social support, and psychological well-being. Findings highlight the importance of interpersonal-cognitive factors for treating depression and improving outcome within bipolar I disorder.

Co-occurring manic symptomatology as a dimension which may help explaining heterogeneity of depression

BACKGROUND

The dichotomous distinction between unipolar and bipolar disorders may be challenged by heterogeneity within diagnoses and overlap between different diagnoses. A broad mood disorder category in which patients differ as a result of variation along separate manic and depressive mood dimensions can be proposed. To test this, it is hypothesized that heterogeneity in clinical and other features of subjects selected for unipolar depression can be partly explained by coexisting manic symptoms.

METHODS

A cohort selected for unipolar depressive disorder was followed up for two years at which time co-occurring manic symptoms were assessed, yielding four groups with increasing manic symptomatology: i) pure unipolar depressive disorder (n=1598), ii) unipolar depressive disorder with subthreshold manic symptomatology (n=64), iii) bipolar II disorder (n=39), and iv) bipolar I disorder (n=86). Multivariate logistic regression and analyses of covariance controlled for depression severity were used to investigate whether patients with increasing manic symptomatology could be differentiated from patients with pure depressive disorder.

RESULTS

Male gender, a lower age at first episode, a history of suicide attempts and increased aggressive cognitions were independently associated with an increase in manic symptoms. The additional presence of (hypo)mania was associated with greater depression severity and more disability than pure depressive disorder.

LIMITATIONS

The groups with manic symptomatology (subthreshold, hypomania and mania) were considerably smaller compared to the pure depression group.

CONCLUSIONS

The heterogeneity in depressive illness can be partly explained by the coexisting variation along the manic symptom dimension. Co-occurring manic symptoms should be taken into account in depression and a symptom dimensional approach of mood disorders may provide phenotypes that are more informative than current mood disorder categories.

Depressive and manic symptoms are not opposite poles in bipolar disorder

OBJECTIVE

This study of 236 individuals with bipolar disorders employed longitudinal analyses to determine whether the symptoms of mania and depression can be understood as one dimension (with depression and mania as opposites) or two relatively independent dimensions.

METHOD

Weekly severity ratings of manic and depression were assessed using the Longitudinal Interval Follow-up Evaluation-II for 72 weeks. The within-subjects correlation of manic and depressive severity was examined using random effects regression.

RESULTS

Contrary to the one-dimension model, mania and depression symptoms were not negatively related. Indeed, the correlations of mania with depressive symptoms were quite small.

CONCLUSION

The data suggest that depressive and manic symptoms are not opposite poles. Rather depressive and manic symptoms appear to fluctuate relatively independently within bipolar disorder.

Berkson's bias and the mood dimensions of bipolar disorder

In this paper we examined whether manic and depressive dimensions independently contribute to mental health service use and determined the degree of comorbidity between manic and depressive dimensions in individuals with and without mental health service use. If both depressive and manic episodes independently influence help-seeking behaviour, a higher level of comorbidity between these dimensions would be found in clinical as compared to non-clinical samples (i.e. Berkson's Bias). Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a prospective epidemiological survey in a representative sample of the Dutch population (N = 7076). Dimensions of depression and mania and mental health service use (MHSU) were assessed with the Composite International Diagnostic Interview (CIDI) at baseline, and prospectively one and three years later. Logistic regression was used to test whether depressive and manic dimensions both had independent effects on mental health service use. The degree of mania-comorbidity given the presence of depressive dimension was assessed as a function of MHSU, both retrospectively and prospectively. Manic and depressive dimensions contributed independently to mental health service use. Mania-comorbidity given the presence of depressive dimension was significantly higher in individuals with mental health service use than in those without, both retrospectively (16.7% versus 7.1%, p = 0.000) and prospectively (10.8% versus 6.6%, p = 0.017). We conclude that the bipolar phenotype consists of manic and depressive dimensions that may be much more loosely associated than (Berkson) biased clinical observations suggest. A dimension-specific approach may be more productive in clarifying the aetiology of mood dysregulation.

Personality trait predictors of bipolar disorder symptoms

The purpose of the current investigation was to examine the personality predictors of bipolar disorder symptoms, conceptualized as one-dimensional (bipolarity) or two-dimensional (mania and depression). A psychiatric sample (N=370; 45% women; mean age 39.50 years) completed the Revised NEO Personality Inventory and the Minnesota Multiphasic Personality Inventory -2. A model in which bipolar symptoms were represented as a single dimension provided a good fit to the data. This dimension was predicted by Neuroticism and (negative) Agreeableness. A model in which bipolar symptoms were represented as two separate dimensions of mania and depression also provided a good fit to the data. Depression was associated with Neuroticism and (negative) Extraversion, whereas mania was associated with Neuroticism, Extraversion and (negative) Agreeableness. Symptoms of bipolar disorder can be usefully understood in terms of two dimensions of mania and depression, which have distinct personality correlates.

Burden of bipolar depression: impact of disorder and medications on quality of life

Bipolar disorder is a complex, chronic psychiatric condition characterized by recurring episodes of depressive illness and mania or hypomania. Although the manic or hypomanic episodes define the disorder, recent research has shown that depressive symptoms predominate over manic symptoms in the majority of patients, and that bipolar depression accounts for much of the significant morbidity and mortality associated with bipolar disorder. Given these findings, there has been a recent upsurge of interest in furthering our understanding of the burden of depression in bipolar disorder. At the same time, increasing scientific attention is now being paid to expanding the measurement of outcome in bipolar disorder to encompass broader indicators of response, one of which is the assessment of quality of life (QOL). In this review, we provide a summary of the current knowledge about QOL in the depressive phase of bipolar disorder, and the effects of pharmacological treatment interventions for bipolar disorder upon QOL. It appears that QOL is poorer in bipolar disorder than in other mood disorders and anxiety disorders, but that schizophrenia might compromise QOL more severely than bipolar disorder. Existing data also suggest that, for patients with bipolar disorder, QOL is negatively associated with depression, both as a cross-sectional mood state and perhaps also as a feature of the patient's course. Despite its clinical and public health importance, bipolar depression has only recently started to receive the attention it warrants in clinical trials, and many important questions about its optimal pharmacological management remain to be answered. There is also a paucity of information about the impact of pharmacological interventions on QOL in bipolar depression. To our knowledge, only two clinical trials to date have specifically examined the impact of medications on QOL in patients with bipolar depression. A small number of other studies have examined the effects of depressive symptoms on QOL in patients who are experiencing manic or mixed episodes. Nonetheless, QOL appears to be a meaningful and important indicator of outcome and recovery in this patient population, and one that warrants further scientific interest and energy.

Diagnostic guidelines for bipolar depression: a probabilistic approach

OBJECTIVES

There are currently no accepted diagnostic criteria for bipolar depression for either research or clinical purposes. This paper aimed to develop recommendations for diagnostic criteria for bipolar I depression.

METHODS

Studies on the clinical characteristics of bipolar and unipolar depression were reviewed. To identify relevant papers, literature searches using PubMed and Medline were undertaken.

RESULTS

There are no pathognomonic characteristics of bipolar I depression compared to unipolar depressive disorder. There are, however, replicated findings of clinical characteristics that are more common in both bipolar I depression and unipolar depressive disorder, respectively, or which are observed in unipolar-depressed patients who 'convert' (i.e., who later develop hypo/manic symptoms) to bipolar disorder over time. The following features are more common in bipolar I depression (or in unipolar 'converters' to bipolar disorder): 'atypical' depressive features such as hypersomnia, hyperphagia, and leaden paralysis; psychomotor retardation; psychotic features, and/or pathological guilt; and lability of mood. Furthermore, bipolar-depressed patients are more likely to have an earlier age of onset of their first depressive episode, to have more prior episodes of depression, to have shorter depressive episodes, and to have a family history of bipolar disorder. The following features are more common in unipolar depressive disorder: initial insomnia/reduced sleep; appetite, and/or weight loss; normal or increased activity levels; somatic complaints; later age of onset of first depressive episode; prolonged episodes; and no family history of bipolar disorder.

CONCLUSIONS

Rather than proposing a categorical diagnostic distinction between bipolar depression and major depressive disorder, we would recommend a 'probabilistic' (or likelihood) approach. While there is no 'point of rarity' between the two presentations, there is, rather, a differential likelihood of experiencing the above symptoms and signs of depression. A table outlining draft proposed operationalized criteria for such an approach is provided. The specific details of such a probabilistic approach need to be further explored. For example, to be useful, any diagnostic innovation should inform treatment choices.

Personality and the predisposition(s) to bipolar disorder: heuristic benefits of a two-dimensional model

OBJECTIVES

The aim of this study was to model normal personality correlates of the predisposition(s) to bipolar disorder (BD), and in so doing explore the proposition that the tendency to bipolar depression [trait depression (T-Depression)] and the tendency to mania [trait mania (T-Mania)] can usefully be viewed as separable but correlated dimensions of BD predisposition.

METHODS

A well student sample (n = 176, modal age 18-25 years, 71% female) completed the NEO Personality Inventory-Revised and the General Behavior Inventory.

RESULTS

A good-fitting model (normed chi2 = 0.60, significance of chi2 = 0.73) was identified in which T-Depression was determined solely by neuroticism, while T-Mania was determined by extraversion and (negative) agreeableness. The pathway from T-Depression to T-Mania was also significant (standardized regression weight = 0.80), with a weaker significant reciprocal path (coefficient = 0.27). A model in which bipolar vulnerability was represented as a single dimension (T-Bipolarity) also provided a good fit to the data, but provided less heuristic power.

CONCLUSIONS

Predisposition to BD can be usefully understood in terms of two reciprocally related dimensions of vulnerability (T-Depression and T-Mania), which can be separated on the basis of their personality correlates.