MDD with subthreshold hypomania ‘should be merged with bipolar II’

By Mark Cowen, Senior medwireNews Reporter

Patients with major depressive disorder plus subthreshold hypomania (MDD[m]) exhibit significant differences in disease course, symptoms, treatment-seeking rates and other characteristics compared with those with major depression alone, research shows.

By contrast, Nicholas Hoertel (Hôpital Louis Mourier, Colombes, France) and team found no significant differences between MDD(m) and bipolar II disorder (BD II) patients regarding such characteristics.

"Given the prevalence, the high risk of suicide, comorbidity and impairment in both disorders, and their similar patterns of clinical manifestations, major depression plus subthreshold hypomania and BD II diagnosis should be merged," suggest the authors in the Journal of Affective Disorders.

"However, the benefits of broadening the diagnostic criteria for hypomania, including earlier and more accurate diagnosis, and more efficient treatment of patients with discrete but significant bipolar disorder, must be balanced against such risks as overdiagnosis and the deleterious effects of inefficient medications," they add.

The findings come from a study of 43,093 individuals who participated in the 2001-2002 US National Epidemiologic Survey on Alcohol and Related Conditions.

All of the participants were assessed for mood disorders using the alcohol use disorder and associated disabilities interview schedule-DSM-IV Version (AUDADIS-IV) during face-to-face diagnostic interviews. Subthreshold hypomania was diagnosed when participants failed to meet full diagnostic criteria for mania or hypomania, but answered positively to at least one of three screening questions for hypomania.

Overall, the lifetime prevalence of MDD alone, MDD(m), BD II, and BD I among the study population was 10.70%, 2.53%, 1.12%, and 2.19%, respectively.

Compared with patients with MDD alone, those with MDD(m) were significantly more likely to have any substance use disorder (adjusted odds ratio [AOR]=1.91), dysthymia (AOR=1.42), and any personality disorder (AOR=2.04).

Participants with MDD(m) also had a younger mean age at the time of their first episode than those with MDD alone (27.81 vs 31.06 years), and had significantly more frequent depressive episodes during their lifetime (6.56 vs 4.31 episodes).

In addition, participants with MDD(m) were significantly less likely to endorse significant weight or appetite loss, insomnia or hypersomnia, and were more likely to report thoughts of suicide and suicide attempts than those with MDD alone. MDD(m) was also associated with lower scores on the social, emotional, and mental health scale of the Short-Form Health Survey-12 than MDD alone.

Furthermore, participants with MDD(m) had significantly higher treatment-seeking rates and had used more medications than those with MDD alone.

There were no significant differences between participants with MDD(m) and those with BD II regarding psychiatric comorbidities, disease course, clinical characteristics, symptoms, health status, and treatment-seeking rates, the researchers note.

"This study provides further evidence of the heterogeneity of MDD, and the validity of distinguishing individuals with [subthreshold hypomania] from those with pure MDD, recently acknowledged in the posted DSM-V update," the authors conclude.

They add: "Future studies would benefit from better defining (subthreshold) bipolar-specifier criteria and evaluating efficacy and adverse effects of antidepressants, mood stabilizers and atypical antipsychotics in patients with subthreshold bipolarity."

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