Dr. Samuels Replies

To The Editor: We agree with Drs. Grootheest and Cath that hoarding behavior may be heterogeneous, “possibly with subtypes related and subtypes unrelated to OCD.” Indeed, on page 498 of our article, we noted that hoarding behavior can occur in conditions other than OCD, and we wrote that “we suspect that hoarding behavior itself is heterogeneous, and that the etiology of hoarding behavior is different in various syndromes.” However, as noted by Dr. Saxena, all of the families in our cohort were recruited because they had two or more relatives affected with OCD, and thus OCD was over-represented in the hoarding participants. On page 497, we suggested that Zhang et al. (1) may have found different linkage peaks for hoarding in their study because they selected families with multiple siblings affected with Tourette’s syndrome, not OCD (1) . Certainly, more work is needed in order to refine the phenotypic definition of hoarding, including the clinical features outlined by Dr. Saxena.

As pointed out by Drs. Van Grootheest and Cath, there was a range of severity in the hoarding individuals in our cohort, but the majority (68%) reported spending at least 1 hour per day and/or experiencing moderate, severe, or extreme distress that was frequent and disturbing during the worst period of their hoarding behavior.

We stand by our conclusion that the findings of our study suggest that a region on chromosome 14 is linked to compulsive hoarding behavior in these OCD families. We hypothesize that there is a genetic variant in this region that increases the risk of hoarding behavior in individuals who are susceptible to OCD. Additional genetic studies are required to replicate these findings and to characterize the genetic variant that may be involved.