Distinct Etiological Influences on Obsessive-Compulsive Symptom Dimensions: A Multivariate Twin Study

Abstract

Background Obsessive-compulsive disorder (OCD) is characterized by five major dimensions, including contamination/washing, harm/checking, symmetry/ordering, hoarding, and forbidden thoughts. How these dimensions may relate etiologically to the symptoms of other obsessive-compulsive related disorders (OCRDs) and anxiety disorders (ADs) is not well known. The aim of this study was to examine the genetic and environmental overlap between each major obsessive-compulsive dimension with the symptoms of other OCRDs and ADs. Methods Two thousand four hundred ninety-five twins of both sexes, aged between 18 and 45 years, were recruited from the Australian Twin Registry. Measures used scores on four dimensions (obsessing (forbidden thoughts), washing, checking, and ordering) of the Obsessive-Compulsive Inventory-Revised, Dysmorphic Concerns Questionnaire, Hoarding Rating Scale, Anxiety Sensitivity Index, Social Phobia Inventory, and Stress subscale of the Depression, Anxiety, and Stress Scale. Multivariate twin modeling methods using continuous and categorized variables were performed, also controlling for age and gender. Results Our findings suggested that forbidden thoughts and washing demonstrated the strongest genetic overlap with other AD symptoms, while ordering was genetically related to OCRD symptoms. Common genetic influences on checking symptoms were best estimated when modeling OCRDs together with AD symptoms. Common environmental factors of ordering and checking were shared with AD symptoms. Conclusions Important shared genetic and environmental risk factors exist between OCD, OCRDs, and ADs, but which vary alongside the expression of its major dimensions.

The polygenic risk for obsessive‐compulsive disorder is associated with the personality trait harm avoidance

“…Despite previous reports of distinct genetic contributions (67, 68), we did not observe any significant associations between the OCD PRS and symptom dimensions as assessed by OCI‐R subscales. This suggests that the relationship between general OCD risk alleles and specific symptom dimensions is not quantitative but may rather be characterized by qualitative differences, that is, specific sets of SNPs or VNTR being linked to specific symptom dimensions (e.g., 69, 70).…”

Genetic and phenotypic overlap of specific obsessive-compulsive and attention-deficit/hyperactive subtypes with Tourette syndrome

“…Two OCD symptom groups, are arguably among the most pathognomonic and recognizable OCD symptoms, were clinically associated with anxiety disorders—contamination/cleaning and doubts/scrupulosity (which includes religious and morality obsessions, checking for mistakes and for inadvertent harm, need to confess, mental rituals, and re-reading/re-writing). Although we do not have sufficient power to examine the genetic relationships between these factors and anxiety disorders, a recent twin study demonstrated strong genetic relationships between washing and religious/sexual obsessions (parallel to our contamination and doubts factors) and anxiety disorders (Lopez-Sola et al 2016).…”

Predictors and consequences of health anxiety symptoms: a novel twin modeling study

“…The OCI‐R total score has excellent psychometric properties . Acknowledging the heterogeneity of the disorder, the OCI‐R evaluates six different OCD symptom dimensions: washing (sum of items 5, 11, 17), checking (sum of items 2, 8, 14), obsessing (sum of items 6, 12, 18), hoarding (sum of items 1, 7, 13), ordering (sum of items 3, 9, 15), and neutralizing (sum of items 4, 10, 16), some of them associated with different etiological patterns . Because of the utility of the OCI‐R for examining OCD symptom dimensions, as demonstrated in our past work , we examined each of these dimensions in relation to HA symptoms.…”