THE RELATIONSHIP BETWEEN PANIC DISORDER AND MAJOR DEPRESSION - A NEW FAMILY STUDY

Objective: The comorbidity between panic disorder and major depression (MDD) in individuals has been amply documented. However, data from fa mily studies to determine whether panic disorder and MDD aggregate sep arately or together in families have been inconclusive, in part becaus e of the absence of studies with the full range of proband groups. Thi s report presents results from a family study with the necessary mutua lly exclusive groups: panic disorder without MDD, panic disorder with MDD, MDD without panic disorder, and normal controls. Methods: Diagnos tic information was obtained from 193 probands and 1047 of their adult relatives with the Schedule for Affective Disorders and Schizophrenia -Lifetime Version for Anxiety Disorders by direct interview, and/or fr om multiple informants, without knowledge of proband diagnoses. Best-e stimate diagnoses were based on all available information by clinician s independently of data collection and without knowledge of probands' and other relatives' status. Results: Findings indicated the specific and independent transmission of panic disorder and MDD, the separation of panic disorder from MDD, and the nonfamilial nature of late-onset MDD. The pattern of results was unaffected by the use of different dia gnostic criteria, number of informants, interview status of relatives, presence of substance abuse or agoraphobia or the sequence of MDD and panic disorder in probands, or whether probands were selected from tr eatment clinics or community sample. Conclusions: We conclude that pan ic disorder and MDD are separate disorders with substantial co-occurre nce in individuals, and that panic comorbid with MDD is not a single, distinct disorder. Finally, we illustrate an approach to examining com orbidity in family data through analysis of mutually exclusive, parall el diagnoses in probands and relatives.