Compared with bipolar disorder type I, individuals with bipolar disorder type II experience higher mood instability during depression, per study data published in the International Journal of Bipolar Disorder.

Investigators abstracted data from the MONARCA II trial, a single-blind parallel-group study on the effect of smartphone-based self-monitoring on patient outcomes. The study cohort comprised patients with a diagnosis of bipolar disorder type I or II who were treated at the Copenhagen Clinic for Affective Disorders in Denmark between 2004 and January 2016. Patients were randomly assigned to 9 months of either daily self-monitoring with the smartphone-based MONARCA II system or treatment as usual. The analysis used only data from the intervention arm. The MONARCA II system allowed for evaluation of the following metrics: mood, sleep duration, medicine intake, activity level, mixed mood, irritability, anxiety, cognitive problems, alcohol consumption, and stress. The severity of patient depressive and manic symptoms was evaluated at baseline and re-evaluated at 4 weeks, 3 months, 6 months, and 9 months using the Hamilton Depression Rating Scale 17-items (HDRS) and the Young Mania Rating Scale (YMRS), respectively. Regression analyses were performed to evaluate the relationship between mood indexes and bipolar disorder type.

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The final analysis included data from 84 patients, of mean (standard deviation [SD]) age 43.0 (12.3); 51 (61.2%) were women. Patients with bipolar disorder type I (n=53) had a mean (SD) baseline HDRS score of 7.9 (5.0) and a mean baseline YMRS score of 4.1 (5.6); patients with bipolar disorder type II (n=31) had a mean baseline HDRS score of 7.2 (6.0) and a mean baseline YMRS score of 2.6 (3.0). In models adjusted for age, gender, and psychopharmacologic treatment, a significant negative association was observed between self-monitored mood and HDRS scores (P <.0001). A strong positive association was also observed between self-monitored mood and scores on the YMRS (P <.0001) in the adjusted models. There was no significant difference by bipolar subtype in mean mood level during the study duration, although patients with bipolar disorder type II had lower mean sleep duration per night (P =.036). Patients with bipolar disorder type II had statistically significantly higher mood instability during periods of depression (P =.034) but lower intensity of mania (P =.043) compared with patients with type I. No significant correlation was identified between mood instability and self-monitored sleep duration, suggesting that lessened sleep duration does not contribute to mood instability in patients with bipolar disorder type II.

These data suggest that bipolar disorder type II is not a “less serious” subtype of bipolar disorder, but rather an illness with distinct symptomatology and equally serious risks. Subsyndromal mood instability may be predictive of worse prognosis and should be explored by further research to identify proper methods of intervention for individuals with bipolar disorder.

Reference

Faurholt-Jepsen M, Frost M, Busk J, et al. Differences in mood instability in patients with bipolar disorder type I and II: a smartphone‑based study. 2019;7(1):5. Int J Bipolar Disord.