While hoarders often lack insight and don't view hoarding of possessions as a problem, they are still subject to outside pressures, he added. They sometimes get calls from public health organizations or their local fire department. Their landlords may give them a hard time, telling them they need to clean up the dwelling or risk being evicted. They may feel embarrassed to have people over or find it difficult to leave napkins and other items behind when they go out to eat at restaurants, Wheaton explained.
Another surprise revealed by the study was the "gender difference in the presentation of the hoarding phenotype," Wheaton said.
Females who have OCD and hoarding tend to be more affected than males, having a broader range of comorbidity, more severe OCD symptoms as measured on the Y-BOCS, greater global impairment on the Global Assessment of Function, and greater dysphoria as assessed on the BDI.
A primary reason for conducting the study, Wheaton said, was to better "refine the phenotype," so that we can classify people into meaningful and more homogeneous groups for genetic studies. NIMH investigators, he noted, are recruiting for a genetic study of OCD, which includes hoarders.
"People can participate from anywhere, because we can do an SCID [Structured Clinical Interview for DSM-IV-TR] over the telephone, and they can have blood drawn by their local physician and mailed to us," he said. Further information is available at www.clinicaltrials.gov, identifier NCT00001548.
Other recently published results from the OCD Collaborative Genetics Study by Samuels and colleagues4 found that those with hoarding symptoms were clinically different from non-hoardersand that in families with OCD, there was significant linkage to compulsive hoarding on chromosome 14.5
While the studies by the Wheaton and Samuels groups add to the understanding of hoarding, Saxena said that they are based on somewhat "skewed data." People in the studies, he said, were recruited on the basis of whether they had OCD and then they were divided into hoarding and non-hoarding subgroups. These studies did not include those who have compulsive hoarding but no other OCD symptoms, which accounts for up to half of all compulsive hoarders in the population.
Recent research on the hoarding phenotype also raises questions about the nosology of compulsive hoarding and OCD.6
"There is mounting evidence that compulsive hoarding should either be a distinct subtype of OCD or listed as a separate disorder that is related to OCD," Saxena declared.
