Comorbid major depression and panic disorder: significance of temporal sequencing to familial transmission

Background: Panic disorder (PD) and major depression frequently coexist but the nature of the relationship is controversial. Our aim was to determine if the risk for depression in a proband is influenced by the temporal sequence of comorbid PD and major depression in an affected family member. Methods: Of participants in a larger study of individuals who had a family, but no personal history of PD, 31 had a first-degree relative with comorbid PD and major depressive disorder (MDD). In 16, the onset of MDD preceded PD (HR-MDPD), and in 15, PD was established before the first depressive episode (HR-PDMD). Thirty-seven low-risk controls (LRC) described no first-degree relatives with psychiatric illness. Participants were assessed using the SADS-LA and provided family history data on first-degree relatives. Results: High-risk subjects whose first-degree relative had temporally primary depression had a 50% chance of having had a major depressive episode. Those with a first-degree relative with primary panic and secondary depression were at no greater risk of having had a depression than were normal controls (6.7% and 5.4%, respectively). Limitations: The use of the family history method has the intrinsic weakness of relying solely on proband knowledge. Conclusion: The temporal relationship between comorbid panic and depression may play an important role in determining the familial risk for depression in family members.