Hoarding has become a subject of widespread fascination in the last decade, with frequent exposure in popular media and an exponential increase in research on the topic.

Reality television has drawn the public eye to compelling stories of people who can’t throw anything away and fill their houses with everything from piles of old newspapers to pets to rotting food.

Notably, in May 2013, the psychiatry community formally recognized hoarding as a distinct disorder with the publication of the DSM-5.

While hoarding has been recognized for centuries, researchers have only recently begun to study the behavior. The first study of hoarding, published by researchers Randy O. Frost and Rachel C. Gross in 1993, defined hoarding as “the acquisition of, and failure to discard, possessions which appear to be useless or of limited value” (Frost RO & Gross RC, Behav Res Ther 1993;31(4):367–381).

Frost and other researchers have continued to study hoarding, contributing to a body of literature that has expanded rapidly in recent years. Frost identifies the central symptoms of hoarding disorder as difficulty discarding objects, urges to save, excessive acquisition of possessions, and cluttered living spaces. He also has described common characteristics of hoarders, including indecisiveness, procrastination, perfectionism, and avoidance (Frost RO, Expert Rev Neurother 2010;10(2):251–261).

Differentiating Hoarding from OCD and OCPD

After much supportive research, hoarding disorder is now listed as a distinct disorder within the category of obsessive-compulsive and related disorders in DSM-5. Studies have found hoarding behaviors can be differentiated into three main categories: pure hoarding, hoarding with comorbid obsessive-compulsive disorder (OCD), and OCD-based hoarding.

When hoarding is OCD-based, it is usually egodystonic, meaning that the behavior is distressing and conflicts with the individual’s sense of self. Furthermore, patients with OCD-driven hoarding are seldom interested in the items that they hoard.

In these cases, hoarding behavior is the product of obsessions, such as symmetry or fear of contamination, rather than the desire to possess objects, and excessive acquisition is usually not present (Mataix-Cols D et al, Depress Anxiety 2010;27(6):556–572). Interestingly, OCD-based hoarding is more likely to involve saving bizarre items, such as household trash or body waste (Pertusa A et al, Am J Psychiatry 2008;165(10:1289–1298).

Prior to the latest edition, the DSM had previously mentioned hoarding only in the context of OCD and obsessive-compulsive personality disorder (OCPD). OCD is a disorder characterized by obsessions and compulsions whereas OCPD is a rigid personality type, characterized by a preoccupation with control and orderliness. Hoarding is historically associated with OCPD, and a description of hoarding behavior remains one of eight criteria of OCPD in DSM-5, specifically patients being “unable to discard worthless objects even when they have no sentimental value.”

However, studies have shown the majority of hoarding occurs independently from OCD and OCPD. Hoarding is a significant problem in less than 5% of OCD patients and most with severe hoarding do not display OCD symptoms. Furthermore, hoarding is weakly associated with OCD symptoms, such as contamination obsessions or checking compulsions, whereas these OCD symptoms are significantly associated with each other. Similarly, hoarding is not strongly associated with other OCPD criteria, such as excessive orderliness or devotion to work (Mataix-Cols D et al, op.cit). This distinction supports the inclusion of hoarding disorder in DSM-5 as a separate diagnosis.

Therapy to Treat Hoarding

Until recently, research on hoarding therapy has focused on cognitive behavioral therapy (CBT) designed for OCD, consisting of standard exposure and response prevention (ERP). However, studies have shown that hoarding symptoms do not improve with this form of treatment.

Frost’s cognitive-behavioral model of hoarding has allowed for the development of a more specialized and promising form of CBT. This model views hoarding as stemming from deficits in information-processing, central vulnerabilities, beliefs about possessions, and reinforcing emotions. Specialized CBT for hoarding has been designed based on this model and demonstrated greater efficacy in trials. Treatment, some of which is home-based, is focused on decision-making training, cognitive restructuring of hoarding-related beliefs, and ERP related to loss of possessions (Frost RO, 2010 op.cit).

A waitlist-controlled trial, published in 2013, studied 37 patients over nine to 12 months, randomized to 26 sessions of hoarding-specialized CBT (n=23) or waitlist followed by CBT (n=23). The study found 41% showed significant change in scores on the Saving Inventory-Revised (SI-R) questionnaire (a standard measure of hoarding behavior) and 71% of patients were rated “much improved” or “very much improved” on clinical global improvement ratings. Some 31 participants provided follow-up data, showing overall retention of CBT outcomes up to one year post-treatment. However, the study did demonstrate that certain factors, including male gender, hoarding severity, perfectionism, and social anxiety, may diminish response (Muroff J et al, Depress Anxiety 2013; online ahead of print).

Other methods of treatment being used, with mixed results, include group therapy, motivational interviewing, and harm reduction.

For details on administering therapy for hoarding disorder, see this month’s interview with Gail Steketee, PhD.

Psychopharmacology

Researcher Sanjaya Saxena and colleagues conducted the seminal study of medication treatment of hoarding, examining 79 patients with OCD (32 patients with compulsive hoarding and 47 non-hoarding patients) treated openly in a prospective study with standardized paroxetine (Paxil) treatment for 12 weeks. Both groups improved significantly, with 50% of the hoarding group and 49% of the non-hoarding group classified as responders.

Interestingly, hoarding symptoms improved as much as OCD symptoms. The UCLA Hoarding Severity Scale (UHSS) was used to assess a subset of hoarding patients, showing a 24% decline in scores. These results suggest serotonin reuptake inhibitors are effective in treating hoarding (Saxena S et al, J Psychiatr Res 2007;41(6):481–487).

The aforementioned team is also currently conducting an open-label trial of extended-release venlafaxine (Effexor XR), prompted by prior knowledge that venlafaxine is as effective as paroxetine for OCD, and better tolerated. Preliminary findings at 12 weeks classified 61% of patients as responders, with more than 30% reduction in UHSS and SI-R scores (Saxena S, J Clin Psychol 2011; 67(5):477–484).

Studies have yet to directly compare CBT and medication treatment, or evaluate combination treatment. Other potentially effective medications that have yet to be studied include glutamate-modulating agents, such as riluzole (Rilutek) or memantine (Namenda), and medications that increase anterior cingulate cortex activity, such as cholinesterase inhibitors, stimulants, or non-stimulants, for example, modafinil (Provigil) (Frost 2010, op.cit).

Weaknesses in Research

Studies examining the responsiveness of OCD patients with hoarding to pharmacotherapy have yielded mixed results. Conventionally, it was thought that hoarding symptoms caused patients to be more treatment-resistant, but it is also possible poor response is due to correlated characteristics of hoarders, including male gender, early disease onset, illness severity, and greater comorbidity.

Studies of treatment methods for hoarding have been chronically problematic due to flaws in the research, including small sample sizes, suboptimal measurements of hoarding, biased recruitment from the OCD population, and retrieval of information from archives (Frost RO, 2010 op.cit). Reviews recognizing these flaws and the inclusion of hoarding disorder in the DSM have spurred improved research methods that will likely produce valuable information about the diagnosis and treatment of hoarding disorder in the future.