Background
Conventional categorical criteria have limitations in assessing the prevalence and severity of depressive mixed state (DMX). Thus, we have developed a new scale for screening and quantification of DMX and examined the symptomatological structure and severity of DMX in individuals with major depressive episode (MDE).
Methods
Subjects were 154 patients with MDE (57 males and 97 females; age 13–83 years). Our original Japanese version of the self-administered 12-item questionnaire to assess DMX (DMX-12), together with the Quick Inventory of Depressive Symptomatology Self-Report Japanese version (QIDS-SR-J) and global assessment of functioning, were administered to each participant. The symptomatological structure of the DMX-12 was examined by exploratory factor analysis. Multiple regression analyses were used to analyze factors contributing to the DMX-12 scale. The relationships of this scale with categorical diagnoses (mixed depression by Benazzi and mixed features by DSM-5) were also investigated.
Results
A three-factor model of the DMX-12 was extracted from exploratory factor analysis, namely, “spontaneous instability”, “vulnerable responsiveness”, and “disruptive emotion/behavior”. Multiple regression analyses revealed that age was negatively correlated with total DMX-12 score, while bipolarity and the QIDS-SR-J score were positively correlated. A higher score on the disruptive emotion/behavior subscale was observed in patients with mixed depression and mixed features.
Conclusion
The DMX-12 seems to be useful for screening DMX in conjunction with conventional categorical diagnoses. Severely depressed younger subjects with potential bipolarity are more likely to develop DMX. The disruptive emotion/behavior subscale of the DMX-12 may be the most helpful in distinguishing patients with DMX from non-mixed patients.
Although the definition of depressive mixed state, more commonly known as mixed depression, is still controversial, about one-third of major depressive episodes are held to contain mixed components. The most frequent manifestations of mixed depression are irritability, distractibility and psychomotor agitation, although these symptoms are not included in the mixed features during a major depressive episode according to the DSM-5 criteria, which is therefore unlikely to cover the full scope of mixed depression in real-world settings. Mixed depression often accompanies risky behavior including impulsive suicide attempts. The early detection and treatment of these unstable conditions is therefore necessary. Also, sufficiently sensitive and specific screening methods for depressive mixed state are needed to avoid both under-and over-diagnosis. Antidepressants should be avoided since these drugs often worsen irritability, agitation and impulsivity, and increase risky behavior. Instead, combination therapy with mood stabilizer(s) to prevent the relapse of the depressive mixed state and atypical antipsychotics for rapid stabilization in the acute phase should be considered. Because there is very little evidence for effective pharmacotherapy in mixed depression, the efficacy of various mood-stabilizing agents, either as monotherapy or in combination therapies, should be extensively examined in the future using quantitative assessments of the psychopathology of mixed depression in patients with confirmed diagnoses of mixed depression.
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