DISTINCT ETIOLOGICAL INFLUENCES ON OBSESSIVE-COMPULSIVE SYMPTOM DIMENSIONS: A MULTIVARIATE TWIN STUDY

Area of Science:

• Psychiatry
• Behavioral Genetics
• Clinical Psychology

Background:

• Obsessive-compulsive disorder (OCD) presents with five distinct dimensions: contamination/washing, harm/checking, symmetry/ordering, hoarding, and forbidden thoughts.
• The etiological relationships between these OCD dimensions and symptoms of other obsessive-compulsive related disorders (OCRDs) and anxiety disorders (ADs) remain largely uncharacterized.
• Understanding these relationships is crucial for developing targeted interventions and elucidating the genetic architecture of these conditions.

Purpose of the Study:

• To investigate the genetic and environmental overlap between the five major dimensions of OCD and the symptoms of other OCRDs and ADs.
• To clarify the shared risk factors contributing to the comorbidity observed between OCD, OCRDs, and ADs.
• To differentiate the etiological influences specific to each OCD dimension in relation to other related disorders.

Main Methods:

• A large-scale twin study involving 2,495 participants (aged 18-45) from the Australian Twin Registry.
• Utilized validated measures including the Obsessive-Compulsive Inventory-Revised (OCI-R), Dysmorphic Concerns Questionnaire, Hoarding Rating Scale, Anxiety Sensitivity Index, Social Phobia Inventory, and the Depression, Anxiety, and Stress Scale (DASS).
• Employed multivariate twin modeling techniques, analyzing both continuous and categorized variables, while controlling for age and gender.

Main Results:

• Forbidden thoughts and washing dimensions showed the strongest genetic overlap with anxiety disorder symptoms.
• The ordering dimension demonstrated a significant genetic relationship with obsessive-compulsive related disorder symptoms.
• Common genetic influences on checking symptoms were most accurately estimated when modeling obsessive-compulsive related disorders and anxiety disorders concurrently.
• Shared environmental factors for ordering and checking symptoms were also associated with anxiety disorder symptoms.

Conclusions:

• Significant shared genetic and environmental risk factors contribute to the comorbidity of OCD, OCRDs, and ADs.
• These shared influences are not uniform and vary depending on the specific dimension of obsessive-compulsive disorder.
• The findings highlight the complex interplay of genetic and environmental factors across these related psychiatric conditions.