The classical point of view—that major depressive episodes (MDEs), no matter what additional symptoms are present, should be treated first line with antidepressants—is now giving way to new a notion. The idea is that MDEs mixed with a few symptoms of mania/hypomania should be viewed very differently in terms of their natural history, clinical outcome, and treatment, and perhaps certain antipsychotics should be given as first-line treatment rather than antidepressant monotherapy.

The newly introduced Mixed Features Specifier of Major Depressive Episode and Disorder (MDE/MDD) is especially challenging in terms of pharmacological management. Prior to the publication of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, the symptoms of the mixed features specifier were intradepressive hypomanic symptoms, always and only associated with bipolar disorder (BD).

Intradepressive hypomanic symptoms, mostly referred to as depressive mixed states (DMX), have been poorly characterized, and their treatment offers significant challenges. To understand the diagnostic context of DMX, we trace the nosological changes and collocation of intradepressive hypomanic symptoms, and examine diagnostic and prognostic implications of such mixed features.

One of the reasons so little is known about the treatment of DMX is that depressed patients with rapid cycling, substance abuse disorder, and suicidal ideation/attempts are routinely excluded from clinical trials of antidepressants. The exclusion of DMX patients from clinical trials has prevented an assessment of the safety and tolerability of short- and long-term use of antidepressants. Therefore, the generalization of data obtained in clinical trials for unipolar depression to patients with intradepressive hypomanic features is inappropriate and methodologically flawed.

A selective review of the literature shows that antidepressants alone have limited efficacy in DMX, but they have the potential to induce, maintain, or worsen mixed features during depressive episodes in BD. On the other hand, preliminary evidence supports the effective use of some atypical antipsychotics in the treatment of DMX.

This article focuses on the controversial decision to exclude the overlapping symptoms of distractibility, irritability, and psychomotor agitation (DIP) with the introduction of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) mixed features specifier. In order to understand the placement of mixed states within the current classification system, we first review the evolution of mixed states. Then, using Kraepelin’s original classification of mixed states, we compare and contrast his conceptualization with modern day definitions. The DSM-5 workgroup excluded DIP symptoms, arguing that they lack the ability to differentiate between manic and depressive states; however, accumulating evidence suggests that DIP symptoms may be core features of mixed states. We suggest a return to a Kraepelinian approach to classification—with mood, ideation, and activity as key axes—and reintegration of DIP symptoms as features that are expressed across presentations. An inclusive definition of mixed states is urgently needed to resolve confusion in clinical practice and to redirect future research efforts.

Mixed affective states, defined as the coexistence of depressive and manic symptoms, are complex presentations of manic-depressive illness that represent a challenge for clinicians at the levels of diagnosis, classification, and pharmacological treatment. The evidence shows that patients with bipolar disorder who have manic/hypomanic or depressive episodes with mixed features tend to have a more severe form of bipolar disorder along with a worse course of illness and higher rates of comorbid conditions than those with non-mixed presentations. In the updated Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM–5), the definition of “mixed episode” has been removed, and subthreshold nonoverlapping symptoms of the opposite pole are captured using a “with mixed features” specifier applied to manic, hypomanic, and major depressive episodes. However, the list of symptoms proposed in the DSM–5 specifier has been widely criticized, because it includes typical manic symptoms (such as elevated mood and grandiosity) that are rare among patients with mixed depression, while excluding symptoms (such as irritability, psychomotor agitation, and distractibility) that are frequently reported in these patients. With the new classification, mixed depressive episodes are three times more common in bipolar II compared with unipolar depression, which partly contributes to the increased risk of suicide observed in bipolar depression compared to unipolar depression. Therefore, a specific diagnostic category would imply an increased diagnostic sensitivity, would help to foster early identification of symptoms and ensure specific treatment, as well as play a role in suicide prevention in this population.

Mood episodes with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5)–defined mixed features are highly prevalent in bipolar disorder (BD), affecting ~40% of patients during the course of illness. Mixed states are associated with poorer clinical outcomes, greater treatment resistance, higher rates of comorbidity, more frequent mood episodes, and increased rates of suicide. The objectives of the current review are to identify, summarize, and synthesize studies assessing the efficacy of treatments specifically for BD I and II mood episodes (ie, including manic, hypomanic, and major depressive episodes) with DSM-5–defined mixed features. Two randomized controlled trials (RCTs) and 6 post-hoc analyses were identified, all of which assessed the efficacy of second-generation antipsychotics (SGAs) for the acute treatment of BD mood episodes with mixed features. Results from these studies provide preliminary support for SGAs as efficacious treatments for both mania with mixed features and bipolar depression with mixed features. However, there are inadequate data to definitively support or refute the clinical use of specific agents. Conventional mood stabilizing agents (eg, lithium and divalproex) have yet to have been adequately studied in DSM-5–defined mixed features. Further study is required to assess the efficacy, safety, and tolerability of treatments specifically for BD mood episodes with mixed features.

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) mixed features specifier provides a less restrictive definition of mixed mood states, compared to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), including mood episodes that manifest with subthreshold symptoms of the opposite mood state. A limited number of studies have assessed the efficacy of treatments specifically for DSM-5–defined mixed features in mood disorders. As such, there is currently an inadequate amount of data to appropriately inform evidence-based treatment guidelines of DSM-5 defined mixed features. However, given the high prevalence and morbidity of mixed features, treatment recommendations based on the currently available evidence along with expert opinion may be of benefit. This article serves to provide these interim treatment recommendations while humbly acknowledging the limited amount of evidence currently available. Second-generation antipsychotics (SGAs) appear to have the greatest promise in the treatment of bipolar disorder (BD) with mixed features. Conventional mood stabilizing agents (ie, lithium and divalproex) may also be of benefit; however, they have been inadequately studied. In the treatment of major depressive disorder (MDD) with mixed features, the comparable efficacy of antidepressants versus other treatments, such as SGAs, remains unknown. As such, antidepressants remain first-line treatment of MDD with or without mixed features; however, there are significant safety concerns associated with antidepressant monotherapy when mixed features are present, which merits increased monitoring. Lurasidone is the only SGA monotherapy that has been shown to be efficacious specifically in the treatment of MDD with mixed features. Further research is needed to accurately determine the efficacy, safety, and tolerability of treatments specifically for mood episodes with mixed features to adequately inform future treatment guidelines.

For the first time in 20 years, the American Psychiatric Association (APA) updated the psychiatric diagnostic system for mood disorders in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Perhaps one of the most notable changes in the DSM-5 was the recognition of the possibility of mixed symptoms in major depression and related disorders (MDD). While MDD and bipolar and related disorders are now represented by 2 distinct chapters, the addition of a mixed features specifier to MDD represents a structural bridge between bipolar and major depression disorders, and formally recognizes the possibility of a mix of hypomania and depressive symptoms in someone who has never experienced discrete episodes of hypomania or mania. This article reviews historical perspectives on “mixed states” and the recent literature, which proposes a range of approaches to understanding “mixity.” We discuss which symptoms were considered for inclusion in the mixed features specifier and which symptoms were excluded. The assumption that mixed symptoms in MDD necessarily predict a future bipolar course in patients with MDD is reviewed. Treatment for patients in a MDD episode with mixed features is critically considered, as are suggestions for future study. Finally, the premise that mood disorders are necessarily a spectrum or a gradient of severity progressing in a linear manner is argued.

Mixed states address the relationships between episodes and the course of an illness, presenting significant clinical challenges. Recurrent affective disorders were described thousands of years ago as dimensional disturbances of the basic elements of behavior, combining the characteristics of what we would now consider manic and depressive episodes. It was recognized from the beginning that combinations of depressive and manic features are associated with a severe illness course, including increased suicide risk. Early descriptions of affective disorders formulated them as systemic illnesses, a concept supported by more recent data. Descriptions of affective disorders and their course, including mixed states, became more systematic during the 19th century. Structured criteria achieved importance with evidence that, in addition to early onset, frequent recurrence, and comorbid problems, mixed states had worse treatment outcomes than other episodes. In contrast to 2000 years of literature on recurrent affective episodes and mixed states, the unipolar–bipolar disorder distinction was formalized in the mid-20th century. Mixed-state criteria, initially developed for bipolar disorder, ranged from fully combined depression and mania to the DSM–5 criteria, no longer limited to bipolar disorder, of a primary depressive or manic episode with at least three symptoms of the other episode type. The challenges involved in understanding and identifying mixed states center largely on what drives them, including (1) their formulation as either categorical or dimensional constructs, (2) the specificity of their relationships to depressive or manic episodes, and (3) specificity for bipolar versus major depressive disorder. Their existence challenges the distinction between bipolar and major depressive disorders. The challenges involved in identifying the underlying physiological mechanisms go to the heart of these questions.

Various terms have been used to describe mania when it is accompanied by depressive symptoms. In this article, we attempt to define and discuss 3 of these terms: dysphoric mania, mixed state, and mania with mixed features specifier. We conclude that whatever term is used, it is important to be aware that mania is more often unpleasant than pleasant, and that the unpleasantness is not limited to depression.

The DSM–5 incorporates a broad concept of mixed states and captured ≥3 nonoverlapping symptoms of the opposite polarity using a “with mixed features” specifier to be applied to manic/hypomanic and major depressive episodes. Pharmacotherapy of mixed states is challenging because of the necessity to treat both manic/hypomanic and depressive symptoms concurrently. High-potency antipsychotics used to treat manic symptoms and antidepressants can potentially deteriorate symptoms of the opposite polarity. This review aimed to provide a synthesis of the current evidence for pharmacotherapy of mixed states with an emphasis on mixed mania/hypomania. A PubMed search was conducted for randomized controlled trials (RCTs) that were at least moderately sized, included a placebo arm, and contained information on acute-phase and maintenance treatments of adult patients with mixed episodes or mania/hypomania with significant depressive symptoms. Most studies were post-hoc subgroup and pooled analyses of the data from RCTs for acute manic and mixed episodes of bipolar I disorder; only two prospectively examined efficacy for mixed mania/hypomania specifically. Aripiprazole, asenapine, carbamazepine, olanzapine, and ziprasidone showed the strongest evidence of efficacy in acute-phase treatment. Quetiapine and divalproex/valproate were also efficacious. Combination therapies with these atypical antipsychotics and mood stabilizers can be considered in severe cases. Olanzapine and quetiapine (alone or in combination with lithium/divalproex) showed the strongest evidence of efficacy in maintenance treatment. Lithium and lamotrigine may be beneficial given their preventive effects on suicide and depressive relapse. Further prospective studies primarily focusing on mixed states are needed.

Mixed states in bipolar disorder have been neglected, and the data concerning treatment of these conditions have been relatively obscure. To address this, we systematically reviewed published pharmacological treatment data for “mixed states/episodes” in mood disorders, including “with mixed features” in DSM–5. We searched PubMed, MEDLINE, The Cochrane Library, clinicaltrials.gov, and controlled-trials.com (with different combinations of the following keywords: “mixed states/features,” “bipolar,” “depressive symptoms/bipolar depression,” “manic symptoms,” “treatment,” “DSM–5”) through to October 2016. We applied a quality-of-evidence approach: first-degree evidence=randomized placebo-controlled studies of pharmacological interventions used as monotherapy; second-degree evidence=a similar design in the absence of a placebo or of a combination therapy as a comparative group; third-degree evidence=case reports, case series, and reviews of published studies. We found very few primary double-blind, placebo-controlled studies on the treatment of mixed states: the preponderance of available data derives from subgroup analysis performed on studies that originally involved manic patients. Future research should study the effects of treatments in mixed states defined using current criteria.

During the past two decades, a number of studies have found that depressed patients frequently have manic symptoms intermixed with depressive symptoms. While the frequency of mixed syndromes are more common in bipolar than in unipolar depressives, mixed states are also common in patients with major depressive disorder. The admixture of symptoms may be evident when depressed patients present for treatment, or they may emerge during ongoing treatment. In some patients, treatment with antidepressant medication might precipitate the emergence of mixed states. It would therefore be useful to systematically inquire into the presence of manic/hypomanic symptoms in depressed patients. We can anticipate that increased attention will likely be given to mixed depression because of changes in the DSM–5. In the present article, I review instruments that have been utilized to assess the presence and severity of manic symptoms and therefore could be potentially used to identify the DSM–5 mixed-features specifier in depressed patients and to evaluate the course and outcome of treatment. In choosing which measure to use, clinicians and researchers should consider whether the measure assesses both depression and mania/hypomania, assesses all or only some of the DSM–5 criteria for the mixed-features specifier, or assesses manic/hypomanic symptoms that are not part of the DSM–5 definition. Feasibility, more so than reliability and validity, will likely determine whether these measures are incorporated into routine clinical practice.

A significant minority of people presenting with a major depressive episode (MDE) experience co-occurring subsyndromal hypo/manic symptoms. As this presentation may have important prognostic and treatment implications, the DSM–5 codified a new nosological entity, the “mixed features specifier,” referring to individuals meeting threshold criteria for an MDE and subthreshold symptoms of (hypo)mania or to individuals with syndromal mania and subthreshold depressive symptoms. The mixed features specifier adds to a growing list of monikers that have been put forward to describe phenotypes characterized by the admixture of depressive and hypomanic symptoms (e.g., mixed depression, depression with mixed features, or depressive mixed states [DMX]). Current treatment guidelines, regulatory approvals, as well the current evidentiary base provide insufficient decision support to practitioners who provide care to individuals presenting with an MDE with mixed features. In addition, all existing psychotropic agents evaluated in mixed patients have largely been confined to patient populations meeting the DSM–IV definition of “mixed states” wherein the co-occurrence of threshold-level mania and threshold-level MDE was required. Toward the aim of assisting clinicians providing care to adults with MDE and mixed features, we have assembled a panel of experts on mood disorders to develop these guidelines on the recognition and treatment of mixed depression, based on the few studies that have focused specifically on DMX as well as decades of cumulated clinical experience.