Pathological Gambling: an Impulse Control Disorder? Measurement of Impulsivity Using Neurocognitive Tests Pinhas N
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IMAJ • VOL 12 • AprIL 2010 REVIEWS Pathological Gambling: An Impulse Control Disorder? Measurement of impulsivity Using Neurocognitive Tests Pinhas N. Dannon MD, Netta Shoenfeld BA, Oded Rosenberg MD, Semion Kertzman MD and Moshe Kotler MD Research Department, Beer Yaakov Mental Health Hospital, Beer Yaakov and Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel blers versus controls, and yet others suggest that impulsivity ABSTRACT: Pathological gambling is classified in the DSM-IV-TR in these gamblers is lower than in controls [5]. (Diagnostic and Statistical Manual of Mental Disorders) Although the term “impulsivity” is widely used, research and in the ICD-10 (International Classification of Disease) has traditionally encountered several difficulties in defining as an impulse control disorder. The association between and exploring the construct of impulsivity. Factor analyses impulsivity and pathological gambling remains a matter of of neuropsychological measures revealed the existence of the debate: some researchers find high levels of impulsivity “inhibitory control” factor; this includes measures derived within pathological gamblers, others report no difference from the Matching Familiar Figures Task, the Go/Stop-Go, compared to controls, and yet others even suggest that it is and the Stop Signal Task [6-16]. lower. In this review we examine the relationship between The Stroop Task [6] is one of the most commonly used pathological gambling and impulsivity assessed by various instruments for the evaluation of cognitive control [7]. This neurocognitive tests. These tests – the Stroop task, the Stop Signal Task, the Matching Familiar Figures Task, the task tests cognitive processes associated with goal-oriented Iowa Gambling Task, the Wisconsin Card Sorting Test, the behavior that selects a weaker, task-relevant response or a Tower of London test, and the Continuous Performance Test potentially stronger, task-irrelevant response [8,9]. Difficulty – demonstrated less impulsivity in gambling behavior. The with inhibitory processing is reflected by an increase in time differences in performance between pathological gamblers in the non-congruent condition of the Stroop test relative to and healthy controls on the neurocognitive tasks could be the neutral condition. Subjects with prefrontal impairment due to addictive behavior features rather than impulsive have difficulty with this task, suggesting that frontally medi- behavior. ated processes are involved in adhering to the goals or rules IMAJ 2010; 12: 243–248 of the task in the face of a competing, stronger (i.e., more KEY WORDS: pathological gambling, impulsivity, neurocognitive tasks, salient, habitual, or prepotent) response [7]. Previous studies Stroop task, Stop Signal Task, Matching Familiar Figures that measured Stroop performance in pathological gamblers Task, Iowa Gambling Task, Tower of London test, Continuous are inconsistent. Some authors have suggested that the pres- Performance Test, Wisconsin card sorting test ence of Stroop impairments is an important characteristic distinguishing pathological gamblers from healthy controls [10], but others reported that the Stroop performance in these gamblers is similar to that of healthy controls, and dif- ferences can only be related to different neural mechanisms For Editorial see page 233 of inhibition control during performance [11]. ambling behavior is defined as placing something of Stop Signal Task constitutes a laboratory analog of a situ- G value at risk with the hope of gaining something of ation that requires an individual to stop a planned or prepo- greater value in return [1]. Pathological gambling is char- tent response [12]. The SST is an objective measure of the acterized by gambling behavior that significantly impairs latency and efficiency of the inhibition process to break the occupational, interpersonal and financial functioning [2]. "go" response when it becomes inappropriate [13,14]. In this Pathological gambling is classified in the Diagnostic test, the examinee is required to make rapid motor responses and Statistical Manual of Mental Disorders [3] and in the on "go" trials but to inhibit responses if a "stop" signal occurs. International Classification of Diseases [4] as a disorder of Response inhibition ability can be quantified by the "stop" impulse control. However, this association between impul- signal reaction time, an estimation of the time taken to inhibit sivity and pathological gambling remains an ongoing issue the wrong motor response [12]. For the calculation of latency, within the literature: some researchers report high levels of it is necessary to know the latencies of starting and finishing impulsivity in pathological gamblers while others cite results implying no difference in impulsivity of pathological gam- SST = Stop Signal Task 243 REVIEWS IMAJ • VOL 12 • AprIL 2010 the "stop" processes. The discrepancy between the two laten- cesses are emotionally neutral decisions with no weighing cies is the SSRT. The stimulus onset asynchrony defines the of rewards and punishments. Cold processes govern real-life start of the "stop" processes, and the end needs to be derived decisions such as planning the details involved in opening a from other results. Inhibition needs to be investigated through new company branch, for example. Risky or hot decisions, on a comparison between conditions with and without response the other hand, involve an evaluation of reward and punish- execution. It becomes harder to suppress a response as the ment, with emotional significance attached to both outcomes. "stop" signal is presented closer to the moment of responding For example, the decision between financing one of several (in other words if SOA is longer). A profile of inhibitory effi- potentially excellent but risky business opportunities is a hot ciency is derived over time by manipulating the SOA between decision; it is difficult to ignore emotions. the response and "stop" signal. It is possible to estimate the effi- Continuous Performance Test provides measures of sus- ciency of response inhibition capacity in the SST that measures tained attention and impulsiveness. This test is one of the most the number of false responses acceptable tests in the diagnosis [12]. The concept of reflection- Pathological gambling is an addictive of attention deficit hyperactiv- impulsivity was introduced by spectrum disorder rather than an impulse ity disorder [20]. ADHD is Kagan in 1964 and refers to the control disorder commonly related to impulsive tendency to gather and evalu- and aggressive behavior with a ate information before making a decision [15]. One of the most propensity to addictions. Some researchers claimed that up widely used behavioral measures of the reflection-impulsivity to 40% of people with ADHD will suffer from at least one dimension is the MFFT psychiatric disorder in their lives. Also, the possibility of this Matching Familiar Figures Task [16] requires subjects to population to become addicts is as high as 20% [21]. However, search a number of similar pictures for only one that matches most pathological gamblers do not suffer from ADHD and a criterion picture exactly. A reflective person tends to con- they have a different behavioral pattern [22,23]. They respond sider various possibilities before making a choice, while an the same as normal controls (unpublished data) impulsive person tends to quickly choose an answer without thoroughly considering alternatives; impulsive behavior has We conducted a Pubmed-Medline search by using the follow- therefore been associated with short latencies and many ing words: pathological gambling, neurocognitive tests, cog- incorrect answers on the MFFT [16,17]. nitive tasks, impulse control disorders, dry addictions, Stroop, Iowa Gambling Task is a frequently used neuropsycho- Go Stop Go, MFFT, Iowa Gambling Test, and Continuous logical test of decision-making ability under initially ambigu- Performance Test. We analyzed the data, and summarized ous conditions. The test simulates real-life decision making the up-to-date evidence and the correlation between patho- by testing the ability of participants to learn to sacrifice logical gamblers and each individual test from Pubmed and immediate rewards in favor of long-term gain. On this task, our patient/control sample. Our aim was to consolidate the patients with medial and orbitofrontal lesions, pathological indications, advantages and disadvantages for preliminary gamblers, and a subset of substance-dependent individuals diagnosis. demonstrate preferences for short-term gains at the risk of larger net losses [17]. Wisconsin Card Sorting Test assesses abstract ability, NEUROCOGNITIVE TESTS namely the ability to shift cognitive strategies in response to • The StroopT ask: This is one measure of selective attention changing environmental conditions, thereby assessing the that has featured prominently in recent studies of cognitive kind of executive functioning that involves strategic planning, biases in addictive behaviors [6]. The original Stroop Task organized searching, and the ability to use environmental incorporated only words relating to color; however, subse- feedback to modify cognitive sets [18]. This task has a differ- quent modified formats have used emotionally salient words ent neuropsychological profile as it is sensitive to damage of to examine cognitive processing associated with emotional the dorsolateral portion of the prefrontal cortex, as well as disturbance and disorders.