Familial transmission of panic disorder: effect of major depression comorbidity.

This study assesses the effect of major depressive disorder (MDD) comorbidity on familial transmission of panic disorder (PD). The following questions are addressed: (1) is PD familial, i.e., do relatives of patients with PD show an increased risk for PD? (2) do PD and MDD share a common diathesis, i.e., do relatives of patients with PD without MDD show an increased risk for MDD? (3) is lifetime comorbid PD with MDD conjointly familial, i.e., do relatives of patients with PD and MDD show an increased risk for the combined syndrome? Subjects were: (1) 152 relatives of 54 anxiety clinic patients with PD and MDD; (2) 193 relatives of 72 patients with PD without MDD; (3) 231 relatives of 77 not ill controls. Relatives were interviewed by clinicians, and best estimate DSM-III-R diagnoses were formulated by senior staff. Relatives of PD with MDD (13%) and PD without MDD probands (9%) showed significantly higher rates of PD than relatives of controls (3%). Relatives of PD with MDD probands (37%) showed significantly higher rates of MDD than relatives of PD without MDD (24%) and controls (21%), with no difference between the latter two groups. Relatives of PD with MDD probands (9%) showed significantly higher rates of PD with MDD than relatives of PD without MDD (3%) and controls (1%). We conclude that: (1) PD is familial; (2) PD in the absence of MDD does not incur increased risk of MDD to relatives; and (3) PD with MDD may represent a distinct, complex syndrome.