Drug and Alcohol Dependence 86 (2007) 287–289
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Impaired decision-making in psychopathic heroin addicts Jasmin Vassileva a,∗ , Pavlina Petkova b , Stefan Georgiev b , Eileen M. Martin a , Ruslan Tersiyski b , Margarita Raycheva c , Vladimir Velinov b , Peter Marinov b a
Department of Psychiatry (MC 912), University of Illinois at Chicago, 1601 West Taylor Street, Chicago, IL 60612, United States b Department of Psychiatry, St-Naum State University Hospital of Neurology and Psychiatry, Sofia, Bulgaria c Department of Neurology, Alexandrovska University Hospital, Sofia, Bulgaria Received 25 April 2006; received in revised form 22 June 2006; accepted 28 June 2006
Abstract Substance-dependent individuals (SDIs) often show neurocognitive deficits in decision-making, such that their choices are biased toward the greatest immediate reward rather than the optimal future outcome. However, studies of SDIs are often hampered by two significant methodological challenges: polysubstance dependence and comorbid conditions, which are independently associated with neurocognitive impairments. We addressed these methodological challenges by testing heroin addicts in Bulgaria, where heroin addiction is highly prevalent but polysubstance dependence is rare. The goal of the current study was to evaluate the potential contribution of psychopathy to decision-making processes among this group of Bulgarian heroin addicts. We tested 78 male currently abstaining heroin addicts, classified as psychopathic or non-psychopathic using the Hare Psychopathy Checklist, Revised (PCL-R). Psychopathic heroin addicts showed notable deficits in decision-making in that they made significantly more disadvantageous decisions relative to non-psychopathic heroin addicts. Results indicate that the presence of psychopathy may exacerbate decision-making deficits in heroin addicts. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Substance dependence; Heroin addiction; Decision-making; Psychopathy
1. Introduction Substance-dependent individuals (SDIs) frequently show decision-making deficits such that their behavioral choices are dictated by the greatest immediate reward rather than the maximally optimal future outcome (Bechara et al., 2001; Grant et al., 2000). The Iowa Gambling Task (IGT) (Bechara et al., 1994), which simulates real-life decision-making in the way it factors uncertainty, rewards, and punishments, is the most widely used task to measure decision-making. However, recent studies (Bechara and Damasio, 2002; Bechara and Martin, 2004) have shown that not all SDIs manifest impairments on the IGT, which suggests that some additional risk factors may influence one’s vulnerability to decision-making deficits. Addressing this problem is hindered by two methodological problems common in any study of neurocognition and drug addiction, namely the high prevalence of polysubstance dependence among SDIs and the presence of comorbid conditions
∗
Corresponding author. Tel.: +1 312 413 0149; fax: +1 312 413 8147. E-mail address:
[email protected] (J. Vassileva).
0376-8716/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.drugalcdep.2006.06.015
characterized by similar decision-making deficits as those exhibited by SDIs. In order to overcome these methodological difficulties, we conducted the current study in Bulgaria, a country with significantly high prevalence of heroin addiction. Importantly, patterns of heroin addiction in Bulgaria are unique in that polysubstance dependence is uncommon. Therefore, the subjects in the current study represent a rare study population in that they are relatively “pure” heroin addicts, not concurrently dependent on other substances. The goal of the current study was to evaluate the potential contribution of psychopathy to decision-making processes among this group of Bulgarian heroin addicts. Psychopathy is a disorder characterized by a constellation of affective, interpersonal, and behavioral characteristics such as egocentricity, impulsivity, shallow affect, lack of empathy, pathological lying, manipulativeness, and persistent violation of social norms (Hare, 1991). Research indicates that psychopathy is closely related to substance use disorders and that it is more strongly associated with illicit drug use than with alcohol use (Taylor and Lang, 2006). Research also reveals that up to one-quarter of drug dependent populations show elevated levels of psychopathy and that among
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heroin-dependent males in particular, the rate climbs to as high as 37.5% (Rutherford et al., 2000). Importantly, there is evidence that psychopathic individuals exhibit decision-making deficits (Blair et al., 2001; Mitchell et al., 2002; vanHonk et al., 2002) that are similar to those evidenced by SDIs. We hypothesized that relative to non-psychopathic heroin addicts, psychopathic heroin addicts would exhibit more pronounced decision-making deficits on the IGT. 2. Methods 2.1. Participants Participants were 78 currently abstinent male heroin users, ages 18–50, who were tested at St-Naum University Hospital of Neurology and Psychiatry in Sofia, Bulgaria. Participants were recruited by informational flyers distributed at outpatient drug treatment centers. Potential participants then contacted study personnel directly. Subjects were compensated for their time. All subjects met DSM-IV criteria for heroin dependence. On average, subjects had been abstinent from heroin use for 372 days, and had abused heroin for 4 years. None of the subjects were on methadone maintenance therapy. Exclusion criteria included: (1) a history of open head injury or closed head injury with loss of consciousness exceeding 30 min; (2) any focal or diffuse CNS illness or injury; (3) schizophrenia, major depression or bipolar disorder; (4) current psychotropic medication; (5) current dependence on alcohol, amphetamines, cocaine, or cannabis; (6) estimated IQ scores below 75. Participants were classified as psychopathic (n = 18) or non-psychopathic (n = 60) based on their scores on the Hare Psychopathy Checklist, Revised (PCL-R; Hare, 1991), a 20-item checklist designed as an objective measure of psychopathy. We employed the standard cutoff score of 25 typically employed in studies with SDIs (Alterman et al., 1993) (i.e. subjects with PCL-R scores greater than 25 were classified as psychopathic and subjects with PCL-R scores below 25 as non-psychopathic).
2.2. Measures The original version of the Iowa Gambling Task (Bechara et al., 2001) converted into Bulgarian was administered on a Dell notebook computer. IGT procedures have been described in detail elsewhere (Bechara and Martin, 2004). Briefly, the task requires participants to make a series of 100 selections from four card decks (A, B, C, and D), with the goal of maximizing their net profit. Unbeknownst to participants, selections from decks A and B (“bad” decks) resulted in large wins but occasional large losses. Choices from decks C and D (“good” decks) resulted in smaller wins and occasional smaller losses. Consistent choices from the good decks provided smaller immediate rewards but ultimately resulted in an overall net gain, whereas choices primarily from the bad decks resulted in an overall net loss.
2.3. Assessment procedures The study was approved by the Institutional Review Boards at University of Illinois at Chicago and St-Naum University Hospital. After signing an informed consent form, participants underwent rapid urine toxicology screen for illicit drugs and a breathalyzer test for alcohol. Subjects who tested positive for either alcohol or drugs received no payment for the visit and were rescheduled for testing on another day. History of substance abuse and dependence was determined using the Structured Clinical Interview for DSM-IV Substance Abuse Module (SCID-SAM: First et al., 1996), translated into Bulgarian. Psychopathy was assessed by the Bulgarian version of the Hare Psychopathy Checklist, Revised (Hare, 1991). The Ravens Progressive Matrices was administered to index estimated IQ. The Beck Depression Inventory, 2nd Edition (BDI-II: Beck et al., 1996) and the State-Trait Anxiety Inventory (STAI: Spielberger, 1983) were administered to assess levels of depression and anxiety, respectively.
Table 1 Demographic, psychological and substance use characteristics
Age Years of education Estimated IQ BDI-II STAI-state STAI-trait Days since last used heroin (medians) Years of heroin use Past alcohol dep (%) Past cannabis dep (%) Past amphetamine dep (%) Past cocaine dep (%)
Psychopathic heroin addicts (n = 18)
Non-psychopathic heroin addicts (n = 60)
25.44 (4.54) 11.22 (2.37) 110.33 (11.02) 9.94 (5.35) 38.44 (10.19) 43.67 (10.69) 195
26.93 (6.61) 11.13 (1.85) 102.43 (2.14) 12.13 (8.01) 38.37 (9.44) 41.28 (9.60) 225
4.31 (1.82) 0 2 (11.1%) 0
4.39 (2.25) 1 (1.7%) 0 0
0
0
Note: All p’s > 0.1.
3. Results 3.1. Group characteristics Univariate ANOVAs and χ2 analyses were used to compare the groups. Groups did not differ significantly in any demographic, substance dependence, or psychiatric characteristics (all p’s > 0.1). Please refer to Table 1 for group statistics. 3.2. Iowa gambling task (IGT) We quantified IGT performance by dividing the 100 trials into five blocks of 20 trials each, and for each trial block calculated the number of cards selected from the “good” decks and the number of cards selected from the “bad” decks. We then calculated a performance “net-score” for each trial block and for each participant by subtracting the number of “bad” deck selections (decks A and B) from the number of “good” deck selections (decks C and D). Net-scores falling below zero indicate a net loss of money and a “disadvantageous” performance, whereas scores greater than zero indicate a net gain of money and “advantageous” performance. We then analyzed IGT performance using a 2 × 5 mixed model ANOVA, with psychopathy (psychopathic, non-psychopathic) as the between subjects factors and IGT Trial Block (Trial Blocks 1, 2, 3, 4, 5) as the within-subject factor. We found an expected significant main effect of IGT Trial Block [F(4,304) = 4.77, p < 0.001], with both groups selecting significantly more cards from the bad decks during the early trials of the task and progressively selecting more cards from the good decks during the later trial blocks. Importantly, there was a significant main effect of psychopathy [F(1,76) = 5.18, p < 0.02], indicating that the psychopathic group made significantly more selections from the bad decks than the non-psychopathic group (Fig. 1). Notably, as a group, the psychopathic heroin users never switched their preferences to the good decks throughout the entire game as their net scores never went above zero on any of the five trial blocks.
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“pure” psychopathic and non-psychopathic heroin addicts who are not dependent on other substances, the present study represents a step toward a more comprehensive understanding of the effects of heroin and psychopathy on decision-making neurocognitive processes. Acknowledgement This research was supported by National Institute on Drug Abuse (NIDA) grant R21 DA18086. References
Fig. 1. Performance of psychopathic and non-psychopathic heroin addicts on iowa gambling task.
4. Discussion To our knowledge, this is the first study to directly investigate the effects of psychopathy on decision-making in currently abstinent heroin addicts by using the IGT. As predicted, psychopathic heroin addicts made significantly more disadvantageous decisions on the IGT, relative to non-psychopathic heroin addicts. Our findings are consistent with studies reporting impaired decision-making in both clinically diagnosed psychopaths (Blair et al., 2001; Mitchell et al., 2002) as well as in non-clinical subjects scoring highly on self reports of psychopathic traits (vanHonk et al., 2002) and with reports (Fein et al., 2004; Mazas et al., 2000) that SDIs with comorbid antisocial personality disorder (ASPD) perform the IGT more poorly than those without ASPD. It is possible that factors common to both psychopathy and ASPD, such as impulse control problems may underlie the impaired performance on the IGT. Overall, results suggest that psychopathy and heroin addiction may exert synergistic detrimental effects on decision-making, but studies that include appropriate control groups of non-SDIs and non-psychopaths are needed in order to address this question directly. It should be noted that the IGT is a complex task and impaired decision-making can be influenced by multiple processes such as cognitive impulsivity, delay aversion, hypersensitivity to reward, hyposensitivity to punishment, or sensation seeking. Therefore, more studies are needed to evaluate more specific mechanisms underlying the decision-making deficits in psychopathic and non-psychopathic SDIs. Studies investigating the effects of specific drugs of abuse on neurocognitive functioning pose significant challenges due to the high prevalence of polysubstance use and multiple comorbid conditions that can confound effects on cognition. Further, compared to cannabis, stimulants, and alcohol, the neurocognitive effects of heroin addiction have been relatively understudied. Therefore, by using a rigorously selected sample of relatively
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