Panic disorder and bipolar disorder: anxiety sensitivity as a potential mediator of panic during manic states

BACKGROUND: Panic disorder (PD) occurs at high rates in bipolar disorder and more commonly than in unipolar depression. Reports of PD onset during hypomania and depressive mania (i.e., mixed states) raise questions about whether the affective disturbances of bipolar disorder play a specific role in the exacerbation or onset of PD. Anxiety sensitivity (AS), a risk factor for PD appears greater in bipolar disorder compared to unipolar depression, although the association of specific mood states with AS remains unknown. METHODS: We examined the association of current mood state (i.e., mixed state, mania or hypomania, bipolar depression, unipolar depression, and euthymia) with Anxiety Sensitivity Index (ASI) scores in 202 individuals with bipolar disorder (n=110) or major depressive disorder (n=92). RESULTS: Current mood state was significantly associated with ASI score (Chi-square=21.2, df=4, p=0.0003). In multiple regression analyses, including covariates for comorbid anxiety disorders, current mania or hypomania was a significant predictor of ASI scores (p<0.04). Current mixed state tended toward a similar association (p<0.10). LIMITATIONS: Conclusions are limited by the study's cross-sectional nature and relatively small sample size. CONCLUSIONS: These findings of elevated AS during manic states, independent of comorbid anxiety disorders, provide preliminary support for the hypothesis that manic states contribute to risk for the development or exacerbation of PD, and that AS may contribute to the high prevalence and severity of PD comorbid with bipolar disorder.