Bipolar-panic disorder comorbidity within bipolar disorder families: a study of siblings

Objectives:  Although anxiety disorders often co-occur with bipolar disorder in clinical settings, relatively few studies of bipolar disorder have looked specifically at panic comorbidity. This report examines lifetime panic comorbidity within a sample of families with a history of bipolar disorder.
Methods:  One hundred and nine probands with bipolar disorder and their 226 siblings were interviewed as part of a family-genetic study. Logistic regression was used to model bipolar disorder as a predictor of comorbid panic in those with affective disorder, with age at interview and gender included as covariates.
Results:  The percentage with panic attacks was low in those without affective disorder (3%) compared with those with unipolar depression (22%) or bipolar disorder (32%). Panic disorder was found only in those with affective disorder (6% for unipolar, 16% for bipolar). When bipolar disorder and unipolar disorder were compared, controlling for age and sex, having bipolar disorder was associated with panic disorder (OR = 3.0, 95% CI = 1.1, 7.8) and any panic symptoms (OR = 2.0, CI = 1.0,3.8) and more weakly with the combination of panic disorder and recurrent attacks (OR = 1.8, CI = 0.9, 3.5).
Conclusions:  The absence of panic disorder and the low prevalence of any panic symptoms in those without bipolar or unipolar disorder suggest that panic is associated primarily with affective disorder within families with a history of bipolar disorder. Furthermore, panic disorder and symptoms are more common in bipolar disorder than in unipolar disorder in these families.