Mixed Depression May Be More Common Than Previously Thought

A study published today in AJP in Advance suggests the presence of “mixed features” (concurrent manic and depressive symptoms) is more common in patients with bipolar disorder—particularly in women—than may be diagnosed using the criteria in DSM-5.

“Our results raise the possibility that relaxing the diagnostic criteria for the mixed features specifier ... may yield greater sensitivity for identifying patients with mixed depression,” Shefali Miller, M.D., a clinical assistant professor of psychiatry and behavioral sciences at Stanford University, and colleagues wrote.

The researchers analyzed the outcomes of 907 adult outpatients with bipolar disorder across 14,310 visits between 1995 and 2002. At each visit, mania and depression symptoms were assessed using the Inventory of Depressive Symptomatology–Clinician-Rated Version (IDS-C) and the Young Mania Rating Scale (YMRS). Patients with an IDS-C score of greater or equal to 15 and a YMRS score between 2 and 12 at the same visit were classified as having mixed depression.

The presence of mixed depression was observed in 2,139 visits (14.9% of total) and among 584 patients (64.4% of total). Those classified as having one or more mixed depression visits also had more symptomatic visits and fewer non-depressed visits compared with those with no mixed depression visits. DSM-5-based definitions of mixed depression (ranging from narrower definitions requiring three or more nonoverlapping YMRS items concurrent with an IDS-C score of greater or equal to 15, to broader definitions requiring two or more nonoverlapping YMRS items) yielded lower mixed depression prevalence rates (6.3% and 10.8% of visits, respectively).

The authors also found that women were significantly more likely than men to experience subthreshold hypomania during visits with depression (40.7% compared with 34.4%). In both groups, however, visits with mixed depression were associated with higher scores on all individual YMRS items, notably language-thought disorder, speech, and increased motor activity—three YMRS items that a previous study suggested were predictive of antidepressant treatment–emergent mania.

“The present findings suggest that the presence of mixed symptoms during depression visits may signal heightened risk for antidepressant-induced mania, warranting particular caution in clinical decision making,” the authors wrote.

For more on the study and the significance of the findings, see a related video by American Journal of Psychiatry Deputy Editor A. John Rush, M.D.

For other related information, see the Psychiatric News article “Lurasidone Effective in Treating Depression With Mixed Features.”

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