Cognitive functioning in compulsive hoarding
Highlights
► Obsessive-compulsive disorder (OCD) and compulsive hoarding (CH) often co-occur. ► It is important to determine whether OCD and CH are related or distinct syndromes. ► We compare OCD and CH on neurocognitive domains. ► Implicit memory appears to be impaired in CH and OCD, albeit more severely so in the former. ► OCD patients seem to perform more poorly on a decision making test than the compulsive hoarders.
Introduction
Compulsive hoarding (CH) is characterized by accumulation of an excessive number of objects due to an inability to discard things of little value. This results in cluttered living and working spaces, often preventing their appropriate use (Frost & Hartl, 1996). CH is a debilitating condition associated with substantial occupational and social impairment, and poses a serious threat to health and safety of household residents (Pertusa et al., 2010). The DSM-V Task Force has questioned whether this condition should be considered part of a broad definition of obsessive-compulsive disorder (OCD) or should be considered a distinct disorder (APA, 2011). On the one hand, CH is often associated with OCD. About 20–40% of OCD patients report hoarding obsessions and compulsions, suggesting that it could be considered a symptom of OCD (Mataix-Cols et al., 2008, Samuels et al., 2002, Wheaton et al., 2008). On the other hand, hoarding is the major symptom in fewer than five percent of these cases (Foa et al., 1995, Mataix-Cols et al., 1999). Moreover, CH is often present in psychiatric disorders other than OCD (Samuels et al., 2008), and often in the absence of any other psychiatric disorder (Steketee & Frost, 2003).
Identifying the specific pattern of cognitive dysfunction associated with compulsive hoarding would be useful in determining its relationship to OCD as well as deriving a fuller understanding of the basis of compulsive hoarding. Frost and Hartl (1996) proposed that deficits in information processing, such as difficulties with categorization, memory, attention, and decision-making are fundamental features of CHs. Results from several recent studies indicate that hoarding individuals perform more poorly than non-clinical control subjects on neurocognitive tests assessing copy organization, visual and verbal recall, attention, implicit learning, and planning and problem solving. Hartl et al. (2004) found that CHs had poorer delayed visual and verbal recall, and used less effective organizational strategies, compared to non-clinical control subjects. Grisham, Brown, Savage, Steketee, and Barlow (2007) found that CHs performed more poorly on tests of spatial attention, working memory, and sustained attention than did clinical and non-clinical control subjects. More recently, Grisham, Norberg, Williams, Certoma, and Kadib (2010) found that CHs performed more poorly on planning and problem solving than control groups. Among individuals with OCD, Lawrence et al. (2006) found higher scores on a hoarding symptom dimension are inversely related to performance on decision-making, as assessed with the Iowa Gambling Task, and Goldman et al. (2008) found procedural learning impairment in an OCD hoarding subgroup.
However, none of these studies directly compared CHs, OCD patients without hoarding, and control subjects. Therefore, we investigated three neuropsychological functions in these three groups. Given prior findings on impaired decision-making and implicit memory in CH, we used the Iowa Gambling Task (IGT) and Serial Reaction Time Task (SRTT) to assess these domains, respectively. We also used the Stop Signal Reaction Time Task (SSRTT) to evaluate motor inhibition, which has been reported to be impaired in contamination and checking (but not hoarding) subtypes of OCD (Chamberlain, Fineberg, Blackwell, Robbins, & Sahakian, 2006). We attempted to clarify and confirm the evidence found for impaired decision-making and implicit memory in compulsive hoarding CH. In addition, we explored motor inhibition, as a recent study has shown that motor inhibition is impaired in the OCD contamination and checking subtypes (Chamberlain et al., 2006). Based on the literature, we hypothesized that impaired decision-making and disturbed implicit memory, but not impaired motor inhibition, would differentiate individuals with CH and OCD.
Section snippets
Participants
The CH group (n = 24) was recruited from the Johns Hopkins Hospital Outpatient Psychiatry OCD clinic (n = 15) and by advertisements (n = 9). Since no DSM-IV criteria exist for CH, subjects were diagnosed as CHs based on a clinical interview to the presence of substantial clutter in their houses and difficulty discarding useless items. The Savings Inventory-Revised (SI-R) (Frost, Steketee, & Grisham, 2004) was used to confirm the CH diagnosis. A score of minimum 29 was suggestive for clinical hoarding
Sample
The study groups did not differ in age, sex, employment status, marital status, or estimated verbal IQ. The mean age of all participants was 43 years (range 19–63). The majority of participants were female, and the mean estimated verbal IQ was 110.3 (SD 9.6). All the participants were Caucasian with the exception of one Asian participant in each of the CH and OCD groups, and three African–Americans in the control group.
Measures
There was a significant difference in the SI-R scores between the hoarding,
Discussion
This study investigated differences in specific cognitive functions between CHs, OCD patients, and control subjects. We found that, compared to control subjects, OCD patients and CHs scored significantly worse on the SRTT. The evidence was strongest for the CHs. This suggests disturbed implicit memory in CH, and a slight impaired implicit memory in OCD patients. On the IGT, an overall learning progression difference was found between the CHs, OCD group and control subjects, suggesting
Conflict of interest
All authors declare to have no conflict of interest.
Acknowledgement
We appreciate the help of Drs. G. Redgrave, N. McLaughlin, and J. Ward in designing the study.
References (33)
- et al.
Insensitivity to future consequences following damage to human prefrontal cortex
Cognition
(1994) - et al.
Decision-making deficits, linked to a dysfunctional ventromedial prefrontal cortex, revealed in alcohol and stimulant abusers
Neuropsychologia
(2001) - et al.
A cognitive-behavioral model of compulsive hoarding
Behaviour Research and Therapy
(1996) - et al.
Measurement of compulsive hoarding: saving inventory-revised
Behaviour Research and Therapy
(2004) - et al.
Implicit learning, thought-focused attention and obsessive-compulsive disorder: a replication and extension
Behaviour Research and Therapy
(2008) - et al.
Neuropsychological impairment associated with compulsive hoarding
Behaviour Research and Therapy
(2007) - et al.
Categorization and cognitive deficits in compulsive hoarding
Behaviour Research and Therapy
(2010) - et al.
Psychometric properties of the OCI-R in a college sample
Behaviour Research and Therapy
(2004) - et al.
Inhibitory control in obsessive-compulsive disorder
Brain and Cognition
(2004) - et al.
Structure of obsessive-compulsive symptoms in pediatric OCD
Journal of the American Academy of Child and Adolescent Psychiatry
(2008)