Comorbidity in panic disorder: II. Chronology of appearance and pathogenic comorbidity.

Ages of onset and the sequence of appearance of panic disorder (PD) and comorbid conditions were determined in a sample of 54 patients with the principal DSM-III-R diagnosis of PD. The onset of PD was earlier in patients with moderate to severe agoraphobia (AG) than in panic patients without AG. Patients with alcohol abuse and drug abuse before the onset of PD also had a tendency to develop PD earlier, which suggests that these conditions might have specifically predisposed to PD. All comorbid disorders, except for major depression, were more likely to precede the onset of PD so that, more often than not, PD appeared as a chronologically secondary condition. However, it was found that only for primary substance abuse such a temporal relationship might denote etiologic relatedness to PD, because of the reduced temporal distance between the onset of primary substance abuse and secondary PD.