OCD symptom severity and comorbid psychiatric diagnoses in a Swedish genetic epidemiological obsessive-compulsive disorder cohort

Abstract

Background: We have established an epidemiological obsessive-compulsive disorder (OCD) cohort in Sweden. Individuals contributed DNA for genotyping and sequencing and also completed a Swedish translation of the Obsessive-Compulsive Inventory-Revised (OCI-R), a self-report questionnaire for assessing the severity and type of symptoms of OCD. This study made use of the OCI-R data to examine the severity and symptom dimensions of OCD as well as comorbidity with other psychiatric disorders. Methods: OCI-R data for 1,134 individuals were available for this study, 1,010 diagnosed with OCD, and 124 diagnosed with chronic tic disorders without OCD used as a comparison group. We first evaluated the psychometric properties of the Swedish translation of the OCI-R. Then, we linked data from the Swedish national registries to access and analyze psychiatric comorbidities of OCD. Results: The Swedish translation of OCI-R demonstrated internal consistency (Cronbach's α = 0.9) and clear agreement with the OCI-R six-factor model. The mean total OCI-R score for females was significantly higher than for males. The most comorbid psychiatric condition to OCD were anxiety disorders (13.6%) and major depression (12%). We observed that individuals with OCD frequently had additional comorbid psychiatric disorders and that the severity of OCD was significantly higher in individuals with at least one additional psychiatric comorbidity compared to individuals with no psychiatric comorbidity. Conclusion: We showed that the Swedish translation of the OCI-R has appropriate psychometric properties. Using an epidemiological framework, we were able to assess the severity and symptom dimensions of OCD and comorbidity with other psychiatric disorders.

The Genetic Architecture of Obsessive-Compulsive Disorder: Contribution of Liability to OCD From Alleles Across the Frequency Spectrum

“…The heterogeneity of OCD should always be considered in the light of psychiatric comorbidity, an approach that is facilitated in samples such as EGOS and NORDiC that are linked to national health registries. For example, in EGOS, using an epidemiological frame, approximately 40% of individuals with OCD have more than one psychiatric comorbidity, with anxiety disorders and major depressive disorder being most common (43). In addition, the severity of OCD was significantly higher in individuals with at least one additional psychiatric comorbidity compared with individuals with no psychiatric comorbidity: higher symptoms of obsessing and ordering, measured using the Obsessive Compulsive Inventory-Revised, were observed in individuals with OCD and at least one additional psychiatric comorbidity.…”

Phenotypic Impact of Rare Potentially Damaging Copy Number Variation in Obsessive-Compulsive Disorder and Chronic Tic Disorders

“…13% of OCD probands with co-occurring bipolar disorder were carriers of pdCNV, including one individual with 16p13.3 deletion. Bipolar disorder is a common co-occurring condition with OCD, reported in approximately 3% to 20% of patients with OCD [ 14 , 59 , 60 ]. In our recent study of OCI-R scores in the EGOS cohort, the total OCI-R score for individuals with OCD and bipolar disorder was significantly higher than individuals with OCD without any co-occurring psychiatric condition ( p -value < 0.01) [ 14 ].…”

“…Given that our source population was sampled from those in specialized psychiatric care, we anticipate that most individuals received some treatment between their oldest diagnosis date and the date they completed the OCI-R questionnaire (we refer to this as the “time difference”). We have previously analyzed the OCI-R data from the EGOS cohort and shown that it had adequate psychometric properties [ 14 ]. In addition, we have shown that the time difference could explain the smaller OCI-R scores in our data compared to other studies [ 14 ].…”

“…We have previously analyzed the OCI-R data from the EGOS cohort and shown that it had adequate psychometric properties [ 14 ]. In addition, we have shown that the time difference could explain the smaller OCI-R scores in our data compared to other studies [ 14 ].…”

“…Importantly, OCD often presents alongside other co-occurring disorders, which tend to be related to OCD—in terms of both phenotypic presentation and underlying physiology. Around 30% of individuals with OCD also have history of a co-occurring diagnosis of Tourette syndrome, a chronic tic disorder [ 1 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], partly due to shared genetic risk [ 21 , 22 ]. Tourette syndrome is perhaps the most well-known diagnosis within the class of chronic tic disorders—a group of childhood-onset neurodevelopmental disorders that are defined by motor and/or vocal (phonic) tics persisting for at least one year.…”