Background: Few studies have examined the impact of gender, age at onset, phenotype and comorbidity in pediatric obsessive-compulsive disorder (OCD) in children. In this naturalistic study we consider these characteristics of OCD in the framework of the 4 OCD phenotypes (contamination/cleaning, order/symmetry, obsessions/checking and hoarding) proposed by Leckman et al. Sampling and Methods: A consecutive series of 257 patients aged 13.6 ± 2.8 years, diagnosed using a DSM-IV-based clinical interview (Schedule for Affective Disorders and Schizophrenia for School Age Children – Present and Lifetime Version), were included. Results: Patients with OCD onset before 12 years of age presented a higher frequency of comorbid tic disorder and disruptive behavior disorders. The type of obsession varied with gender: order/symmetry was more frequent in males, contamination/cleaning in females. Order/symmetry had the highest comorbidity with tics, contamination/cleaning was the least severe according to the Clinical Global Impression Severity, and was associated with a high rate of comorbid anxiety and depression, similarly to sexual-religious obsessions. Hoarding was the severest according to the Clinical Global Impression Severity, and was associated with a high comorbidity with social phobia and bipolar disorder. Tic comorbidity was more prevalent in males, had an earlier onset, and a heavier comorbidity with attention deficit hyperactivity disorder and other disruptive behavior disorders. A comorbid attention deficit hyperactivity disorder was associated with an earlier onset of OCD and a poorer response to treatments. Conclusions: OCD phenotypes and comorbidities may have marked clinical and prognostic implications. Tertiary care population results may not generalize to less impaired juvenile populations.

This paper reports on implications of bipolar disorder (BD) co-morbidity in 120 children and adolescents with obsessive-compulsive disorder (OCD) (84 males, 36 females, age 13.7 +/- 2.8 years), diagnosed using a clinical interview according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria, and naturalistically followed-up for 12 +/- 6 months. The aim of this naturalistic, retrospective study was to explore the effect of BD co-morbidity, disentangling it from other co-occurring variables, namely the co-morbidity with disruptive behavior disorders. Forty three patients (35.8%) had a bipolar co-morbidity. Compared with OCD patients without BD, they had an earlier onset of OCD, a greater severity and functional impairment, more frequent hoarding obsessions and compulsions, and a poorer response to treatments. They had a higher co-morbidity with attention-deficit/hyperactivity disorder (ADHD) and oppositional-defiant disorder (ODD), and a lower co-morbidity with generalized anxiety disorder (GAD). Finally, they received more mood stabilizers, and 30.2% of them did not receive serotonin-selective reuptake inhibitors (SSRIs) because of pharmacological (hypo)mania. When all the OCD responders and nonresponders were compared, nonresponders (n = 42, 35%) were more severe at baseline and at end of the follow-up, had more frequently hoarding obsessions and compulsions, and had more frequent BD, ODD, and conduct disorder (CD) and less GAD and panic disorder. In the final regression model, hoarding obsessions and compulsions, co-morbidity with ODD, and CD were negative predictors of treatment outcome. This study suggests that even though bipolar co-morbidity is frequent and affects phenomenology and co-morbidity in pediatric OCD, its effect on treatment response seems prevalently accounted for by co-morbidity with disruptive behavior disorders. The significance of the hoarding subtype deserves further research on larger samples of pediatric patients.

Our study suggests that putative variables associated with response to pharmacological treatment of paediatric OCD can be defined, and can help improve treatment strategies.