Affective disorders in the first-degree relatives of bipolar probands: results from the South Island Bipolar Study.

The current study was performed to document observed rates of affective disorders in the first degree relatives of probands with bipolar I or II disorder; to determine whether bipolar II probands have an excess of bipolar II relatives; and to determine whether bipolar probands with a history of one or more suicide attempts have more relatives who have also made suicide attempts. Bipolar probands with positive family histories of affective disorder were recruited from a variety of sources for a study on the molecular genetics of bipolar disorder. Probands and relatives were interviewed with the Diagnostic Interview for Genetic Studies (DIGS) and blood was obtained for DNA extraction and genetic analyses. Among 423 first-degree adult relatives of 153 bipolar probands, 7% (29) had bipolar I disorder, 7% had bipolar II disorder, and 7% had bipolar not otherwise specified (NOS) disorder, making 21% of relatives with any bipolar disorder. A further 42% of relatives had a depressive disorder and only 38% had no affective disorder. A suicide attempt by a proband was not associated with any increase in suicide attempts by relatives. We conclude that while unipolar depressive disorders are the most common affective disorders in the first-degree relatives of bipolar probands, extension of the bipolar phenotype to include bipolar spectrum disorders results in 21% of relatives having any bipolar disorder.

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.