Obsessive-compulsive disorder and separation anxiety co-morbidity in early onset panic disorder.

BACKGROUND: This study was undertaken to examine the relationship between anxiety co-morbidity and age of onset of panic disorder. METHODS: Age of onset of panic disorder and co-morbid anxiety disorders were assessed among 201 panic disorder probands with childhood separation anxiety disorder, obsessive-compulsive disorder, obsessive-compulsive symptoms, social phobia and specific phobia as part of a clinician-administered lifetime diagnostic interview. A generalized linear model was used to test the association between each anxiety co-morbidity and age of panic disorder onset while simultaneously controlling for the potential confounding effects of sociodemographic characteristics and other psychiatric co-morbidity. RESULTS: Earlier onset of panic disorder was found in patients with co-morbid obsessive-compulsive disorder, obsessive-compulsive symptoms and separation anxiety disorder, but not simple phobia or social phobia. Patients with both childhood separation anxiety disorder and obsessive-compulsive disorder had an even earlier panic onset than those with either childhood separation anxiety disorder or obsessive-compulsive disorder. CONCLUSIONS: The association between anxiety co-morbidity and earlier onset of panic disorder is specific to obsessive-compulsive disorder and childhood separation anxiety disorder.