Participants
Participants were 26 adults with a primary diagnosis of HD, 37 adults with a primary diagnosis of a DSM-5 (American Psychiatric Association, 2013) anxiety disorder (ANX), and 28 adult healthy control participants without psychiatric disorders (HC). Participants were recruited from the regular patient flow at an anxiety disorders specialty clinic, through a registry of individuals who had previously consented to be contacted about research opportunities at the clinic, and through media advertisements and flyers posted throughout the surrounding community.
All participants were required to be fluent in English, be right-handed, and have no history of anoxic or traumatic brain injury with loss of consciousness greater than five minutes and no history of neurocognitive disorder that may interfere with the ability to understand the study tasks and provide informed consent. Any history of psychotic disorder or bipolar disorder, current substance use disorder, and serious suicide risk were also exclusionary.
Inclusion criteria for the HD group were a primary diagnosis of HD of at least moderate severity as indicated by a Clinical Global Impression (CGI) (Guy, 1976) rating of 4 or greater. Inclusion criteria for the ANX group were a primary diagnosis of a DSM-5 anxiety disorder of at least moderate severity as indicated by a CGI rating of 4 or greater. For both clinical groups, comorbid conditions were permitted as long as they were secondary to the primary diagnosis. Antidepressants, stimulants, and benzodiazepines were permitted at stable dosages for a minimum of eight weeks. All other psychiatric medications were excluded. For participants taking benzodiazepines and stimulants, a 24-hour “washout” of these medications was required prior to the study with the prescriber’s approval. Inclusion criteria for the HC group were no past or current psychiatric disorders or mental health treatment.
As shown in Table 1, although we attempted to match the control groups to the HD group for age and sex assigned at birth, we had significant age differences. As such, we controlled for age in all study analyses. We note that we assessed sex assigned at birth and not gender identity to be consistent with the National Institute of Mental Health National Data Archive (NDA), in order to facilitate data transfer to the NDA (a requirement of the grant). As expected, the HD group scored significantly higher than did the control groups on the Saving Inventory-Revised (SI-R), a measure of hoarding severity.
Table 1