Decoding Hoarding: A New Frontier

Hoarding disorder (HD) has been considered a type of obsessive-compulsive disorder (OCD). Now, there is mounting evidence against this notion. One of the most compelling is a research examination performed by Tolin et al. (2012). David F. Tolin, Ph.D., is from the Institute of Living in Hartford, Connecticut. The other authors are from various institutions.

Research 2012: The Neural Mechanism

In this study, the researchers examined three groups: patients with HD and OCD, comparing them to healthy controls (HC). In all, there were 107 subjects, 43 of whom had been diagnosed with HD, 31 with OCD, and 33 who were HC.

Each group was asked to bring a piece of junk mail from home to the laboratory. This mail, as well as junk mail furnished by the lab, was photographed. Then, the subjects’ brain activation in deciding whether a piece of mail should be retained or discarded was measured using functional magnetic resonance imaging (fMRI).

In this fMRI, the location of the anterior cingulate gyrus appears in yellow.

Source: CC0 1.0 Universal Public Domain Dedication

Patients with hoarding disorder displayed minimal activation levels in the insula and anterior cingulate cortex (ACC) while they assessed what to do with the experimenter’s mail. These are brain areas involved in decision-making and emotional regulation. On the other hand, when the HD group was deciding what to do with their own mail, these same brain regions burned brightly. Consistent with this, the patients with HD opted to remove fewer pieces of personal junk mail compared to the other groups.

This observation and others like it gave the organizers of the Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental

Disorders (DSM-5) important information. From that time on, they designated hoarding disorder differently than previously. Originally, it had been considered a form of OCD. Now, it is a distinct condition included under "OCD and related disorders."

Clinical Differences Between HD and OCD

Hoarding disorder is characterized by persistent difficulty discarding or parting with possessions, regardless of their actual value. There is a perceived need to save them, and personal distress is associated with discarding them. This leads to significant clutter that disrupts the hoarder's ability to use living spaces as intended. A hoarder might say, “If I were to throw away any of my stuff, it would cause me too much pain and anxiety to bear.”

Obsessive-compulsive disorder, on the other hand, involves intrusive, unwanted thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) performed to reduce the distress associated with obsessions. Such an afflicted person might say, “I am compelled to wash my hands repeatedly so I don’t have germs on them that could cause disease.”

Treatment Differences Between HD and OCD

Selective serotonin reuptake inhibitors (SSRIs), commonly used to treat OCD, are often less effective in treating HD. This suggests different underlying neurochemical pathways. Cognitive-behavioral therapy (CBT) tailored for HD focuses on decision-making, organizational skills, and cognitive restructuring related to attachment to possessions. It is less effective for OCD, again suggesting different pathways for the two. A new therapy for HD advertised by the Mood Center in Annapolis, Maryland, combines ketamine and transcranial magnetic stimulation (TMS). To my knowledge, it has not been rigorously tested for this purpose, so any benefit would be anecdotal.

Research 2023: Trial of CBT for HD

In one of several follow-up examinations to that 2012 study, Tolin and colleagues used group CBT (2023) for 16 weeks for 64 treatment-seeking patients with HD. They were compared to those on a waiting list. Again, as in the 2012 study, functional magnetic resonance imaging was used to examine neural activity during simulated decisions about whether to acquire and discard objects.

The aim of the study was to determine whether the therapeutic benefits of CBT follow improvements in the ACC dysfunction noted in the 2012 examination or abnormalities previously identified in other brain regions. During both acquiring and discarding decisions, activity decreased in several regions. In this study, however, the ACC activity did not show any dramatic change. As the researchers concluded, “Therapeutic benefits of CBT for HD do not appear to be mediated by changes in ACC activation.” By implication, it is my understanding that the insula was also not affected.

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Summary

HD and OCD, despite some superficial similarities, are fundamentally different in terms of their neurological underpinnings, clinical manifestations, and responses to treatment. Future research should continue to explore these distinctions, particularly through longitudinal studies and larger sample sizes.