The familiality of specific symptoms of obsessive-compulsive disorder

This study aimed to assess whether a family history of specific OCD symptoms was associated with the same OCD symptoms in study participants. Participants were sampled from the Nepean OCD study (N=206) and were assessed with the Yale-Brown Obsessive-Compulsive Scale Symptom Checklist (YBOCS-SC) and the Vancouver Obsessional Compulsive Inventory (VOCI) in order to determine their OCD symptoms. A family history screen was used to determine whether participants had a first-degree relative with a history of any of the following specific symptoms: hoarding, contamination/cleaning, symmetry/ordering, doubt/checking and/or other OCD symptoms. The characteristics of participants with a family history of a specific OCD symptom were compared to those of participants with a family history of any other OCD symptom. This was repeated for each specific OCD symptom. The roles of co-occurring tics and age of onset of OCD were also assessed. Distinct familial associations were detected for the symptoms of hoarding and contamination/cleaning. Age of onset of OCD was significantly younger in participants who reported a family history of "other" symptoms. These findings suggest that certain OCD symptom dimensions are more familial than others, which has significant implications for aetiology of OCD.