Minimal extant literature and no systematic data exist on the challenging clinical dilemma of children and adolescents who present with obsessive-compulsive disorder (OCD) that is comorbid with bipolar disorder (BPD). Individually, each disorder may inflict a significant burden on children and their families with a prevalence of at least 1% (1
). Although the diagnosis of BPD in children has generated some controversy in the child psychiatry community, recent reports suggest that it is not uncommon in clinical settings, and, when present, is often accompanied by high levels of anxiety, including OCD (4
). Despite the fact that descriptions of OCD symptoms in patients with BPD date back to the 19th
), almost all reports on the comorbidity of BPD and OCD are descriptive rather than systematic and focus exclusively on adults (13
). In adults, evidence of a higher than expected overlap between OCD and BPD first came from the Epidemiological Catchment Area study, where 23% of those with BPD also met criteria for OCD (16
). Subsequent studies have consistently found a greater than expected overlap between OCD and BPD at rates as high as 15–35% (17
The unexpectedly frequent concurrence of these two disorders may have both clinical and scientific implications. OCD and BPD comorbidity in adults may herald an episodic course of OCD with higher rates of certain obsessions (aggressive/impulsive, sexual, religious, and obsessional doubts) and compulsions (compulsions of control, hoarding, ordering/arranging), which require more frequent hospitalizations and complex pharmacological interventions (17
). Similarly, the presence of OCD comorbidity has been reported to predict a more chronic course of BPD and greater frequency of major depressive episodes, with a trend toward poor response to mood stabilizers (17
). Because pharmacological treatments of the two illnesses diverge and medications used to manage OCD can exacerbate BPD symptoms, their co-occurrence is a therapeutic challenge for clinicians.
Despite the frequent juvenile onset of both OCD and BPD, little attention is paid to the presence of comorbid OCD and BPD in youth. Rates of comorbid OCD in the range of 15–44% have been reported in pediatric BPD populations (4
) and, similarly, studies of OCD have documented comorbidity rates of mania as high as 27–45% (24
The only reports addressing the clinical presentation of comorbid OCD and BPD in a pediatric population suggest that when BPD and OCD co-occur in young patients, both clinical syndromes have a substantial and additive impact on clinical presentation and global functioning (24
If, as the literature suggests, BPD and OCD co-occur in children and adolescents at rates greater than expected with significant bidirectional overlap, the nature of this relationship remains underexamined. Identification of BPD and OCD comorbidity based on DSM nomenclature (27
) may represent as an artifact a secondary phenomenon (28
), an unusual manifestation of a more severe form of disorder, a product of the selection bias (referral or ascertainment), or instead, a marker for a specific subtype of disorder (29
). Alternatively, BPD and OCD could represent valid comorbid ‘nosologically true’ disorders. If nosologically true, then the syndromatic presentation and associated clinical correlates, including other comorbidities and functional indices of each disorder, should be readily recognizable in children who present with both the disorders, and furthermore, neither referral nor ascertainment bias should substantially alter the clinical characteristics of each disorder.
Parsing out the relationship between comorbid disorders has significant therapeutic implications, as the decision to treat either one or both the disorders may be dictated by whether or not one disorder is secondary to the other. Additionally, scientific delineation of comorbid BPD and OCD from OCD and mood disorders may lead to the identification of a more homogeneous clinical subtype of disorder with distinct psychopathology, familiality, and genetic underpinnings.
One avenue for the exploration of the BPD and OCD comorbidity is the examination of the symptom presentation and other clinical correlates of BPD and OCD in the context of reciprocal comorbidity and ascertainment status. If the clinical correlates of the comorbid disorders are indistinguishable from their respective typical presentation and if their comorbid presentation does not alter with different focus for ascertainment, it would suggest that the comorbidity is a valid co-occurrence of disorders and not an artifact. We hypothesized that children and adolescents who fulfill the DSM nosological criteria of both BPD and OCD suffer from both the disorders. To this end, we analyzed data on children and adolescents with BPD and OCD ascertained contemporaneously for a study of pediatric OCD and of pediatric BPD with an aim to compare the clinical characteristics of OCD and BPD in youth (i) with and without reciprocal comorbidity and (ii) with reciprocal comorbidity ascertained through an OCD diagnosis versus those ascertained for a BPD diagnosis.