Mixed depression and the dimensional view of mood disorders

Validating a two-dimensional bipolar spectrum model integrating DSM-5's mixed features specifier for Major Depressive Disorder

INTRODUCTION

The literature on DSM-5's 'Major Depressive Disorder with lifetime mixed features' (MDD-MF) is limited. This study investigated MDD-MF's potential inclusion into a bipolar spectrum.

METHODS

We recruited 287 patients with Bipolar I disorder (BD-I), BD-II, MDD-MF or 'MDD without lifetime mixed features' (MDD-noMF); most (N=280) were stabilized for at least one year on medication. Sixteen validators (clinical features, psychiatric family history, temperament, stabilizing treatment) were compared across groups and subjected to trend analyses. Two discriminant function analyses (DFA; primary and secondary), excluding or including, respectively, treatment-related predictors, explored latent dimensions maximizing between-group discrimination; mahalanobis distances between group 'centroids' were calculated.

RESULTS

Eleven validators differed significantly across groups; nine varied monotonically along a bipolar diathesis gradient with significant linear trends; two peaked at MDD-MF and displayed significant quadratic trends. In the primary DFA, apart from a classic bipolarity dimension, correlating with hospitalizations, early age at onset, lifetime psychosis and lower anxious temperament scores, on which groups ranked along a bipolar propensity gradient, a second dimension was also significant, peaking at BD-II and MDD-MF (challenging the classic bipolar ranking), which correlated with lifetime psychiatric comorbidities, suicidality, lower lifetime psychosis rates, female gender, higher cyclothymic and lower depressive temperament scores; MDD-MF was equipoised amidst BD-II and MDD-noMF. After including treatment-related predictors (secondary DFA), discrimination improved overall but BD-II and MDD-MF were closest than any other pair, suggesting similar treatment patterns for these two groups at this naturalistic setting.

CONCLUSIONS

To our knowledge, this is the first time a two-dimensional bipolar spectrum based on classic external validators is proposed, fitting the data better than a unidimensional model. Additional predictors are warranted to improve BD-II/MDD-MF discrimination.

The bipolar spectrum: conceptions and misconceptions

OBJECTIVE

This review aims to address concerns about the potential overinclusiveness and vagueness of bipolar spectrum concepts, and also, concerns about the overlap between bipolar illness and borderline personality.

METHOD

Narrative review based on historical and empirical studies.

RESULTS

Bipolar disorder (BD) and major depressive disorder (MDD) came to be separate entities with the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM III), in contrast to the Kraepelinian manic-depressive insanity (MDI) concept, which included both. The bipolar spectrum concept is a return to this earlier Kraepelinian perspective. Further, very different features differentiate the disease of bipolar illness (family history of bipolar illness, severe recurrent mood episodes with psychomotor activation) from the clinical picture of borderline personality (dissociative symptoms, sexual trauma, parasuicidal self-harm). The term 'disorder' obfuscates an ontological difference between diseases, such as manic-depressive illness, and clinical pictures, such as hysteria/post-traumatic stress disorder/dissociation/borderline personality.

CONCLUSIONS

Bipolar spectrum concepts are historically rooted in Kraepelin's manic-depressive illness concept, are scientifically testable, and can be clearly formulated. Further, they differ in kind from traumatic/dissociative conditions in ways that can be both historically and scientifically established.

Bipolar spectrum: a review of the concept and a vision for the future

This paper reviews the bipolar spectrum concept historically and empirically. It describes how the concept derives from Kraepelin, but was lost with DSM-III, which divided the broad manic-depressive illness concept, based on recurrent mood episodes of either polarity, to the bipolar versus unipolar dichotomy, based on allowing non-recurrent mood episodes of only one polarity. This approach followed the views of Karl Leonhard and other critics of Kraepelin. Thus post DSM-III American psychiatry is not neo-Kraepelinian, as many claim, but neo-Leonhardian. The bipolar spectrum approach, as advocated by Akiskal and Koukopoulos first, harkens back to the original broad Kraepelinian view of manic-depressive illness. The evidence for and against this approach is discussed, and common misconceptions, including mistaken claims that borderline personality is similar, are revealed and critiqued.

Mixed states with predominant manic or depressive symptoms: baseline characteristics and 24-month outcomes of the EMBLEM cohort

BACKGROUND

While factors associated with mixed states have been extensively studied, data are scant regarding the clinical heterogeneity of mixed states. The EMBLEM study was a prospective, observational study on patients with manic and mixed states. We describe and compare baseline characteristics and 24-month clinical course of mixed states with predominant depressive symptoms (MSDS) and mixed states with predominant manic symptoms (MSMS).

METHODS

Adult inpatients/outpatients with bipolar disorder were enrolled within the standard course of care if they initiated or changed oral medication for acute mania or mixed states. A logistic regression was used to identify the baseline factors associated with each polarity. Comparisons with mixed episode without symptom predominance (OMS) were performed for informational purpose only.

RESULTS

About 573 mixed patients were analyzed (23.7% of the cohort): 59.5% (n=341) had MSMS, 11.9% (n=68) had MSDS, and 28.6% (n=164) had OMS. At baseline, hallucinations/delusions during the index episode, inpatient status, high CGI-BP overall score, and low education level were more often associated with MSMS versus MSDS. Alcohol abuse or dependence and selective serotonin reuptake inhibitor (SSRI) or benzodiazepine use at inclusion were significantly more frequent with MSDS. MSDS had a significantly lower 24-month recurrence rate than MSMS; MSMS experienced more switches to mania whereas MSDS switched more to depression.

LIMITATIONS

The post hoc dimensional definitions in the study require caution in the interpretation of the results.

CONCLUSION

These results present evidence of clinical heterogeneity within mixed states. Predominant manic or depressive symptoms within mixed episode could influence clinicians' decisions in term of hospitalization, treatment, and perception of bipolar severity.

Phenomenology of racing and crowded thoughts in mood disorders: a theoretical reappraisal

BACKGROUND

Racing thoughts is a frequent symptom in mood disorders, particularly mixed depressive states. This paper aims to summarize our current knowledge about its phenomenology and frequency in the spectrum of mood disorders, and to offer a new theoretical framework.

METHODS

We made a selective review of original and review papers in Medline and PsychInfo database using the keywords "racing thoughts", "crowded thoughts" and "depressive mixed state" in conjunction with "mood disorders".

RESULTS

In the context of a hypomanic state, "racing thoughts" may appear as a result from an excessive production of thoughts, moving quickly from one to the other, and generating a sense of fluidity and pleasantness. In the context of depression, "racing thoughts" are phenomenologically different and better described as "crowded thoughts": they are not only characterized by too many thoughts occurring at the same time in the field of consciousness, but perceived as unpleasant and induce the feeling that ideas are difficult to catch. DISCUSSION AND CLINICAL RELEVANCE: We suggest that crowded thoughts might result from the mixture of a hypomanic component, with an accelerated production of new thoughts (constituting the main source of this symptom in hypomania), and a depressive component, with a deficit of inhibition of previous thoughts (hence making thoughts crowded rather than truly racing). This distinction could help better identify crowded thoughts, and consequently depressive mixed states, which has important implications for therapeutic management. It might also help to further disentangle the psychobiological processes which contribute to the complexity of mood disorders.