• antidepressant activation;
  • bipolar disorder;
  • bipolar linkage;
  • comorbidity;
  • rapid cycling;
  • rapid switching of mood

Objective:  Rapid switching of moods in bipolar disorder has been associated with early age at onset, panic comorbidity, and suicidality. This study aims to confirm these associations and investigate other potential correlates of rapid switching of mood using families from a multisite bipolar linkage study.

Methods:  The subjects were comprised of 1,143 probands and relatives with diagnosis of bipolar disorder. All subjects were interviewed directly with a standard diagnostic instrument, and all subjects who met criteria for bipolar disorder were asked if their moods had ever switched rapidly.

Results:  Individuals with rapid mood switching had significantly earlier age at onset (18 versus 21 years, p < 0.00001), higher comorbid anxiety (47% versus 26%, p < 0.00001) and substance use disorders (52% versus 42%, p = 0.0006), higher rate of violent behavior (6% versus 3%, p < 0.004), suicidal behavior (46% versus 31%, p < 0.00001), and nonsuicidal self-harm (13% versus 6%, p < 0.0002). Multiple logistic regression analysis found significant net effects on rapid mood switching for early emergence of symptoms [odds ratio (OR) = 0.62; 95% confidence interval (CI): 0.45–0.85]; anxiety comorbidity (OR = 2.31; 95% CI: 1.34–3.98); and hypersensitivity to antidepressants (OR = 2.05; 95% CI: 1.49–2.83) as the strongest predictors.

Conclusions:  This confirms earlier reports associating rapid switching with a more complex clinical course, in particular early emergence of bipolar symptomatology, antidepressant activation, and anxiety comorbidity. These results support a clinical differentiation of bipolar disorder into subtypes based on symptom stability.