Neuropsychological performance, impulsivity, ADHD symptoms, and novelty seeking in compulsive buying disorder
Introduction
Compulsive buying disorder (CBD) is characterized by excessive or poorly controlled preoccupations, urges, or behaviors regarding shopping and spending that lead to subjective distress or impaired quality of life (Black, 2007, Black, 2010). The disorder has an estimated rate of nearly 6% in the adult United States population (Koran et al., 2006). CBD is associated with co-occurring mood, anxiety, substance use, and other impulse control disorders (Black et al., 1998, Mϋller et al., 2009, Müller et al., 2010a). While most epidemiological and clinical research suggests the disorder has a female preponderance (Black, 2010), the survey reported by Koran et al. (2006) found nearly equal rates in men and women. The disorder is not included in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 2000), and there are presently no plans to include it in DSM-5 (www.dsm5.org).
The appropriate classification of CBD has been debated, but some consider it a behavioral addiction similar in many respects to classic alcohol and drug dependencies (Hollander and Allen, 2006). The concept of behavioral addiction includes disorders that the National Institute on Drug Abuse (NIDA) considers relatively pure models of addiction because the presence of an exogenous substance does not contaminate their processes (Holden, 2001). In addition to CBD, potential behavioral addictions include pathological gambling (PG), kleptomania, compulsive sexual behavior, and Internet addiction (Black et al., 2012). These disorders share common core clinical features such as the performance of repetitive behaviors despite negative consequences, diminished control over their urges, craving prior to engaging in the behavior, and experiencing a pleasurable response while engaged in the behavior (Grant et al., 2006). Other potential categorizations have been proposed for these disorders. Hollander, 1993a, Hollander, 1993b and others (Koran, 1999) have long promoted the concept of an obsessive–compulsive spectrum, but evidence is limited (Dell'Osso et al., 2006, Tavares and Gentil, 2007). Others have suggested that behavioral addictions are related to bipolar disorder (Di Nicola et al., 2010a, Di Nicola et al., 2010b).
Converging evidence from the fields of genetics, neuropharmacology, and brain imaging suggests that CBD is a neuropsychiatric syndrome (Black, 2007, Black, 2010, Raab et al., 2010). The disorder appears familial and has a genetic relationship with mood and substance use disorders (McElroy et al., 1994, Black et al., 1998). Some investigators believe that disturbed neurotransmission may underlie CBD. This belief has prompted the use of selective serotonin reuptake inhibitors to treat the disorder (Black et al., 2000, Ninan et al., 2000, Koran et al., 2003, Koran et al., 2007), though results have been mixed. Dopamine has been conjectured to play a role in CBD because it is widely believed to mediate reward dependent behaviors (Holden, 2001). The role of dopamine is further suggested by reports that anti-parkinsonian medications that modulate dopamine neurotransmission induce compulsive behaviors including uncontrolled shopping (Lader, 2008). Case reports suggest that naltrexone may help in treating CBD, leading to speculation about the role of opiate receptors in CBD, but naltrexone also affects dopamine neurotransmission (Kim, 1998, Grant, 2003). Finally, a recent functional magnetic resonance imaging study of 23 women with CBD found increased activation of the nucleus accumbens – the brain's putative pleasure center – compared to normal shoppers when subjects were shown products they could buy (Raab et al., 2010). These findings are in agreement with the work of Knutson et al. (2007) who studied purchasing decisions (though not in people with CBD), and of studies of persons with PG or drug addiction whereby images of appropriate stimuli activate the nucleus accumbens (Berridge, 2003, Reuter et al., 2005).
Neuropsychological studies could contribute to a better understanding of the neurobiology of CBD. Research investigations with pathological gamblers have suggested the executive function deficits may be associated with disturbances in fronto-temporal circuitry thereby contributing to impaired decision-making (Goudriaan et al., 2004, Forbush et al., 2008, Marraziti et al., 2008). Because both disorders are considered behavioral addictions, it is not unreasonable to propose that people with CBD might have similar neuropsychological profiles to those with PG. Bechara (2003) has described patients with executive function deficits as having a “myopia of the future” because of their failure to consider future consequences. This is an apt description of many people with CBD.
Knowledge of selected personality traits may also help clinicians better understand and manage CBD. There is a growing appreciation that, like PG, CBD is associated with trait impulsivity, despite the fact there have been few formal investigations. Lejoyeux et al. (1997) reported that a group of 38 depressed inpatients with CBD had elevated trait impulsivity on all three subscales of the Barratt Impulsiveness Scale (Barratt, 1959). DeSarbo and Edwards (1996) used the NEO Personality Inventory (NEOPI; Costa and McCrae, 1985) in a group of 104 self-identified persons with CBD and found high levels of impulsiveness. Mϋller et al. (2010b) recently used the NEOPI to assess personality in a group of 68 compulsive buyers. Cluster analysis yielded two clusters, one of which was associated with greater CBD severity, higher trait impulsivity, more comorbid psychiatric disorders, and lower rates of remission.
We have become increasingly interested in assessing childhood and adult symptoms of attention deficit hyperactivity disorder (ADHD) in pathological gamblers, symptoms that research shows are relatively common in these individuals (Black et al., in press). Interestingly, we have found not only high levels of ADHD symptoms in people with PG, but that these levels fall with treatment of the disordered gambling (Black et al., 2007a, Black et al., 2007b, Black et al., 2008). This could suggest that ADHD symptoms help mediate disordered gambling or, possibly, they are behavioral markers of the disorder. The same could be true for CBD. None of the published CBD comorbidity studies (Christenson et al., 1994, Schlosser et al., 2004, Black et al., 1998, Müller et al., 2010a) have reported on the prevalence of ADHD symptoms. This may have more to do with the lack of assessment rather than the lack of an association, because the instruments used in these studies have not assessed ADHD.
The purpose of this pilot study was to gain a better understanding of the neuropsychological performance of persons with CBD. Because CBD and PG appear to intertwine (de Zwaan, 2010), we thought it worthwhile to also assess trait impulsivity, ADHD symptoms, and selected personality characteristics. Based on our experience, and drawing from the literature on PG, we expected people with CBD to perform more poorly on neuropsychological tests, including indices of executive function (e.g., cognitive flexibility, decision-making) than controls, but that general cognition and memory would not differ between the groups. We further hypothesized that persons with CBD would have higher levels of trait impulsivity and ADHD symptoms, and that those who were highly impulsive would perform more poorly on tests of executive function and comprise a subset. Developing a better understanding of the interrelation of neuropsychological performance, trait impulsivity, and ADHD symptoms in persons with CBD has the potential to foster new treatment approaches and preventive strategies.
Section snippets
Subjects and study design
Men and women ≥18 years who met the criteria of McElroy et al. (1994) for CBD were recruited through newspaper advertisements and word-of-mouth. Subjects had to score ≥2 standard deviations below the mean on the Compulsive Buying Scale (CBS), shown to differentiate compulsive from non-compulsive buyers (Faber and O'Guinn, 1992). They also had to have CBD for ≥1 year. Control subjects were recruited in the course of another study through advertisements (Black et al., in press). Controls could
Data analysis
χ2 tests (or Fisher's exact tests) and t-tests were used to compare demographic and clinical characteristics of the groups. ANOVA was used to compare neuropsychological characteristics of the two groups (SAS Institute Inc., 2004). The neuropsychological variables compared included measures of memory (HVLT total recall and delayed recall, BVMT total recall and delayed recall), executive functioning (WCST total errors, perseverative responses, non-perseverative errors, perseverative errors,
Baseline comparison
Twenty-eight persons with CBD were recruited and screened. Two were later dropped from the analysis for not meeting study criteria (one due to a bipolar disorder, the other due to a history of head injury and loss of consciousness). Controls were collected in the course of another study. From a pool of 65 subjects, 32 were selected to approximately match the age, sex, and educational profile of the group with CBD. The final sample consisted of 26 subjects with CBD and 32 controls.
The groups
Discussion
People with CBD in this pilot study were similar demographically and clinically to those described by other investigators, and their disorder was of moderate severity (Christenson et al., 1994, McElroy et al., 1994, Ninan et al., 2000, Miltenberger et al., 2003, Koran et al., 2003, Koran et al., 2007). In short, CBD was primarily a disorder of middle-aged women who had struggled with the condition for nearly 17 years. We were able to confirm some, but not all of our hypotheses. First, we found
Acknowledgments
The study was funded in part through grants from the National Center for Responsible Gaming and the National Institute on Drug Abuse (RO1DA021361 to Dr. Black). Dr. Black has received research support from Psyadon and AstraZeneca. Drs. Allen and Bayless, Mr. McCormick, and Ms. Shaw report no conflicts.
References (79)
Development of a multilingual aphasia battery: progress and problems
Journal of the Neurological Sciences
(1969)Pleasures of the brain
Brain and Cognition
(2003)- et al.
Extended-release carbamazepine in the treatment of pathological gambling: an open-label study
Progress in Neuropsychopharmacology and Biological Psychiatry
(2008) - et al.
Emotional reactions in adults with symptoms of attention deficit hyperactivity disorder
Personality and Individual Differences
(1997) - et al.
Typologies of compulsive buying behavior: a constrained clusterwise regression approach
Journal of Consumer Psychology
(1996) - et al.
Quetiapine as add-on treatment for bipolar I disorder with comorbid compulsive buying and physical exercise addiction (letter)
Progress in Neuro-Psychopharmacology & Biological Psychiatry
(2010) - et al.
Behavioural addictions in bipolar disorder patients: role of impulsivity and personality dimensions
Journal of Affective Disorders
(2010) - et al.
Mini-mental state: a practical method for grading the cognitive state of patients for the clinician
Journal of Psychiatric Research
(1975) - et al.
Pathological gambling: a comprehensive review of biobehavioral findings
Neuroscience and Biobehavioral Reviews
(2004) - et al.
Direct and retrospective assessment of factors contributing to compulsive buying
Journal of Behavioral Therapy and Experimental Psychiatry
(2003)