Evidence for clinical heterogeneity in mixed bipolar states

By Mark Cowen, Senior medwireNews Reporter

Research suggests that there are significant clinical differences between bipolar disorder patients who experience mixed mood states with predominant depressive (MSDS) or manic symptoms (MSMS).

The team found that MSDS and MSMS patients differed significantly regarding the presence of hallucinations/delusions, Clinical Global Impression for Bipolar Disorder (CGI-BP) scores, education level, alcohol abuse/dependence rates, and switching rates.

"These results present evidence of clinical heterogeneity within mixed states," say Laurent Baraille (Eli Lilly and Company, Suresnes, France) and colleagues.

The team studied 573 bipolar disorder inpatients and outpatients with an index mixed mood episode, of whom 341 (59.5%) had MSMS and 68 (11.9%) had MSDS. The remaining 164 (28.6%) patients had no predominant polarity during mixed episodes.

The researchers found that, at baseline, patients with MSMS were significantly more likely to be inpatients (47.9 vs 22.1%) and have hallucinations/delusions during the index episode (49.0 vs 27.7%) than those with MSDS.

Patients with MSMS also had significantly higher overall CGI-BP scores than those with MSDS (4.90 vs 4.51), as well as significantly lower levels of educational attainment.

Alcohol abuse/dependence rates were significantly higher in MSDS than MSMS patients (25.0 vs 8.8%) as was the use of selective serotonin reuptake inhibitors (39.7 vs 19.6%).

Furthermore, over a 2-year follow-up period, patients with MSDS were significantly less likely to switch to mania (7.4 vs 37.8%) and more likely to switch to depression (22.1 vs 4.4%) than those with MSMS.

Baraille and team conclude in the Journal of Affective Disorders: "Numerous factors associated with predominant manic or depressive symptoms within mixed states support the concept of clinical heterogeneity providing evidence in favor of a continuum within mixed states."

They add that the findings are important as "predominant manic or depressive symptoms within mixed episodes could… influence clinicians' decisions in term of hospitalization, treatment (antidepressants and sedatives), and perception of bipolar severity."

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