SPECIAL REPORT: OCD AND RELATED DISORDERS
• BD-OCD comorbidity’s burden and clinical management is a critical issue in psychiatry.
• The evidence so far on BD-OCD nosology, which is mainly based on the course of illness, supports the view that the majority of cases of comorbid BD-OCD are in fact BD cases. Obsessive-compulsive symptoms usually are secondary manifestations of depressive or manic mood episodes.
• Mood stabilization should be the primary goal in treating patients with BD-OCD. Because of the risk of worsening BD via serotonin reuptake inhibitors-induced mania/hypomania, antidepressants should only be used in a minority of cases of refractory OCD.
In a classic 1970 publication, the famous epidemiologist Alvan R. Feinstein, MD, defined comorbidity in relation to a specific index condition as “any distinct additional entity that has existed or may occur during the clinical course of a patient who has the index disease under study.”1 In Feinstein’s formulation, the implication was that a completely different and independent disease occurred at the same time as another disease. These two diseases co-occurred, more often than not, randomly.
On the other hand, DSM explicitly offers overlapping clinical criteria for many diagnoses, especially mood and anxiety disorders, guaranteeing comorbidity in quite a different sense than in the medical meaning of the term as co-occurrence of independent diseases. Using the DSM definition, it is unclear whether concomitant diagnoses actually reflect the presence of distinct clinical entities or refer to multiple manifestations of a single clinical entity.
A little bit of history
A good example of this problem is the comorbidity of bipolar disorder (BD) and OCD. More than half of patients with BD have an additional diagnosis, one of the most difficult to manage being OCD. More than 150 years ago, French psychiatrist Bénédict-Augustin Morel first described patients with BD-OCD, which resulted in questions regarding nosology and the clinical meaning of this condition.
In a standard 1969 psychiatry textbook, Mayer-Gross and colleagues,2 who had a significant focus on course of illness, included patients with BD-OCD in the manic-depressive disorders.2
In the hierarchical approach to diagnosis, which contradicts the DSM comorbidity approach, anxiety presentations like OCD should not be diagnosed as separate conditions when co-occurring with mood presentations such as BD. In other words, OCD should not be diagnosed unless BD is ruled out. If this non-DSM approach is correct, patients with OCD should be evaluated for family history for mood disorders, course of illness of mood symptoms in relation to OCD symptoms, and other evidence of bipolarity.
BD-OCD comorbidity has importance in nosology as well as therapeutic implications. The question of nosology is whether this common comorbidity represents two separate diseases that co-occur by chance, or a severe subtype of BD or OCD. The therapeutic question is whether and how to treat the comorbidity since the main treatment for OCD serotonin reuptake inhibitors (SRIs) can worsen BD.
Although recent studies have looked at the co-occurrence of anxiety and bipolar disorders, there is insufficient research and the relationship between BD and OCD remains unclear. Given the available scientific evidence, however, some observations can be made (Table).
Apparent BD-OCD comorbidity is a common condition in psychiatry (Figure). Recent data from a large cross-continental multiple OCD treatment center study (3711 patients with OCD), showed a lifetime prevalence of comorbidity with BD-I and BD-II of 4.5% and 23.7%, respectively.3
In our meta-analysis, the pooled prevalence of OCD in BD was 17.0% (95% CI 12.7-22.4), which was comparable to the results reported by the pooled prevalence of BD in OCD (18.35%, 95% CI 13.2-24.8).4
Although limited by retrospective study design, small sample size, different thresholds for BD diagnosis (ie, categorical versus dimensional approach) and a different accuracy in diagnosing OCD (ie, discrimination between true ego-dystonic obsessions and depressive ruminations), these results confirm the relevance of comorbid BD-OCD.
Dr Amerio is Researcher and Psychiatrist, Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), Section of Psychiatry, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy; and Mood Disorders Program, Tufts Medical Center, Boston, MA. Dr Costanza is Chargée d'einsegment et de Recherche, Psychiatrist and Neurologist, Department of Psychiatry, Faculty of Medicine, University of Geneva (UNIGE), Geneva, Switzerland; Department of Psychiatry, ASO Santi Antonio e Biagio e Cesare Arrigo Hospital, Alessandria, Italy. Dr Aguglia is Researcher and Psychiatrist, DINOGMI, Section of Psychiatry, University of Genoa, and IRCCS Ospedale Policlinico San Martino; Dr Serafini is Associate Professor, DINOGMI, Section of Psychiatry, University of Genoa, and IRCCS Ospedale Policlinico San Martino. Dr Brakoulias is Conjoint Professor, School of Medicine, Western Sydney University, Blacktown Hospital, Sydney, NSW, Australia. Dr Amore is Professor, DINOGMI, Section of Psychiatry, University of Genoa, and IRCCS Ospedale Policlinico San Martino. Dr Ghaemi is Professor, Mood Disorders Program and Department of Psychiatry, Tufts University Medical School, Boston, MA. Drs Amerio, Costanza, Aguglia, Serafini, Brakoulias, and Amore report no conflicts of interest concerning the subject matter of this article; Dr Ghaemi reports that he is employed by Novartis Institutes for Biomedical Research and holds equity in Novartis.
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