House of Mind

To hoard or not to hoard…

But first, let’s define the term hoarding… According to An et. al (2009), compulsive hoarding is both the acquisition of and the inability to discard a large number of possessions that appear to be useless and have no value. As some of you may expect, compulsive hoarding is present in many cases of OCD, and has been usually been studied in that clinical context. 

Throughout the years, neuroimaging studies have linked hoarding symptoms in OCD patients with multiple brain areas. Mataix-Cols et. al (2004) found distinct neural correlates for the different symptoms present in OCD patients such as washing, checking and hoarding. Importantly, the study found that hoarding behaviors were most significantly correlated with right orbitofrontal cortex and left precentral gyrus activation.  Other brain areas implicated in hoarding behaviors in OCD patients include the right sensorimotor cortex and the fusiform gyrus. Additionally, lesions studies of human ventromedial prefrontal cortex have resulted in the emergence of hoarding behaviors that were not present before, which combined with other findings in patients with hoarding symptoms, has led to the hypothesis of ventromedial prefrontal cortex involvement in compulsive hoarding.

In order to determine the neural correlates of hoarding symptoms in OCD patients, An and colleagues recruited three subject groups: a group w/ OCD and strong hoarding symptoms, a group w/ OCD but no significant hoarding symptoms and a group of healthy controls. The image above is part of the results of this study, and shows the brain regions significantly more activated in hoarders than in non-hoarders and controls (shown in red in (a) and (b), and in healthy controls more than in hoarders and non-hoarders (shown in blue in (b) and (c) during hoarding symptom provocation. The box plots depict the percent change in blood oxygen level dependent (BOLD) responses for each group.  

All three groups showed increased activation in widespread areas of the brain such as:

• Ventral, paralimbic, and dorsal prefrontal brain regions (including bilateral visual regions)
• Ventrolateral, dorsolateral, and dorsomedial prefrontal regions
• Cerebellum
• Anterior insula
• Temporal cortex

However, some areas were only activated in specific groups. For example, only hoarders activated large clusters in the frontal pole (including a large bilateral cluster in the anterior vmPFC), extending ventrally to the anterior part of the orbitofrontal cortex and dorsally to the medial frontal gyrus. Specifically, this vmPFC cluster is spatially situated anterior to areas implicated in the decision-making circuit. The non-hoarding OCD group significantly activated the caudate putamen while the controls showed activation in the striatum, left thalamus and the vmPFC (including the orbitofrontal cortex and the anterior cingulate cortex).

Note: The study also emphasized on the role of anxiety in compulsive hoarding symptoms and related brain activation. They suggest that OCD patients with compulsive hoarding symptoms have higher anxiety levels (provoked by the experimental simulation task of “choosing” which objects to discard) that correlate with greater activation in the vmPFC and other temporal lobe areas like the uncus, parahippocampal gyrus, hippocampus, amygdala, and more. Mataix-Cols et. al have also found an effect of anxiety on brain activation during a similar task.

Sources:

An, SK, et. al. 2009. To discard or not to discard: the neural basis of hoarding symptoms in obsessive-compulsive disorder. Molecular Psychiatry. 14 (3): 318-31. doi:10.1038/sj.mp.4002129

Mataix-Cols, D. et al. 2004. Distinct neural correlates of washing, checking, and hoarding symptom dimensions in obsessive-compulsive disorder. Arch Gen Psychiatry. 61 (6): 564-576.