Inventory identification of cyclothymia. IX. Validation in offspring of bipolar I patients.

We present the ninth in a series of validation studies that support the effectiveness of the General Behavior Inventory (GBI) in identifying cyclothymia. This study assessed the potential utility of the GBI in family and offspring studies by evaluating its ability to satisfy three prerequisites for use in such research: (1) identification of cyclothymia familially related to bipolar I disorder, (2) use with young adolescents, and (3) "insensitivity" to the effects of nonaffective psychopathology and parental nonaffective disorder in the offspring of control probands. The GBI and a blind, structured diagnostic interview were administered to 37 offspring of bipolar I patients and 21 offspring of psychiatric control patients, Twenty-seven percent of the offspring of bipolar patients, but none of the control offspring, were found to have bipolar forms of affective disorder, primarily cyclothymia (24%). Concordance between the GBI and interview-derived diagnoses was 95% to 97%, with 98% specificity and 80% to 90% sensitivity, depending on cutting score location. Together with the results of previous studies, the findings suggest that the GBI holds promise for the identification of cyclothymia in several research and clinical contexts.