Differential parental influence in the familial aggregation of obsessive compulsive disorder

• Parental Influence in the transmission of characteristics related to OCD was examined.
• Paternal OCD is associated with earlier age of onset of OCD symptoms.
• Paternal OCD is associated with a greater number of comorbid diagnoses.
• Paternal OCD is associated with symmetry and exactness obsessions.
• These findings are specific to paternal rather than maternal OCD.

The familial nature of OCD has been well established. Clinical characteristics such as early age of onset, comorbidity with tic disorders, and higher rates of symmetry symptoms have been associated with the familial aggregation of OCD, though little research has examined the differential impact of paternal and maternal OCD. The current study explored parental influence on the expression of these characteristics and reports on 310 probands diagnosed with OCD as well as 1580 of their biological first-degree relatives. The probands were evaluated by trained clinical raters using semi-structured assessments, and relative diagnoses were obtained based on probands’ reports. Similar to previous findings, 10.13% of the 1580 relatives (n=160) were reported to have significant OCD symptoms. Only probands who reported having a father with OCD, rather than any first-degree relative, were more likely to have an early age of onset, symmetry and exactness obsessions, and higher rates of comorbidity. No significant differences were found with respect to the probands who reported their mothers as having OCD. These findings suggest that paternal OCD, rather than simply any first-degree relative having OCD, may influence whether probands exhibit the clinical characteristics commonly associated with the familial subtype of OCD.