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Are all drug addicts impulsive? Effects of antisociality and extent
of multidrug use on cognitive and motor impulsivity
Jasmin Vassilevaa,⁎, Raul Gonzaleza, Antoine Becharab, Eileen M. Martina,c
aDepartment of Psychiatry, University of Illinois – Chicago, Chicago, IL 60622, USA
bDepartment of Psychology, University of Southern California, Los Angeles, CA 90089, USA
cJesse Brown Veterans Administration Medical Center, Chicago, IL 60622, USA
The purpose of this investigation was to examine the influence of antisociality and extent of multidrug use on
cognitive and motor impulsivity among substance-dependent individuals (SDIs) that used primarily cocaine and/or
heroin. One hundred currently abstinent male SDIs participated in the study. Extent of multidrug use and degree of
antisociality, assessed with the Socialization Scale of the California Psychological Inventory (So-CPI), were used
to classify participants into one of four groups: high antisocial/low multidrug use, high antisocial/high multidrug
use, low antisocial/low multidrug use, and low antisocial/high multidrug use. All subjects completed the Iowa
Gambling Task to assess cognitive impulsivity and the Stroop Task to measure motor impulsivity. Contrary to
expectations, antisociality was associated with more advantageous performance on the Iowa Gambling Task,
independent of extent of multidrug use. In contrast, greater multidrug use was associated with general psychomotor
slowing on the Stroop Task. Results suggest that a subclinical form of antisociality may have a paradoxically
facilitating effect on decision-making and cognitive impulsivity among SDIs.
© 2007 Elsevier Ltd. All rights reserved.
Keywords: Drug addiction; Impulsivity; Antisocial; Polysubstance use; Multidrug use; Decision-making
Impulsivity is a multidimensional construct, considered a core component in drug addiction (Goldstein
and Volkow, 2002). Reward-discounting or cognitive impulsivity refers to the preference for smaller
immediate rewards over larger delayed rewards, whereas rapid-response or motor impulsivity is manifested
Addictive Behaviors 32 (2007) 3071–3076
⁎Corresponding author. Department of Psychiatry (MC 912), University of Illinois – Chicago, 1601 West Taylor Street,
Chicago, IL 60612, USA. Tel.: +1 312 413 0149; fax: +1 312 413 8147.
E-mail address: email@example.com (J. Vassileva).
0306-4603/$ - see front matter © 2007 Elsevier Ltd. All rights reserved.
Author's personal copy
Garcia and Perez-Garcia, 2007). However, not all SDIs manifest such impairments, which suggests that
study explored whether two potential risk factors, namely antisociality and extent of multidrug use, both
commonly observed in SDIs (Craig, 2000; Leri et al., 2003) and previously related to poor impulse control
SDIs. We used the Iowa Gambling Task (IGT) and the Stroop Task: two common laboratory paradigms to
be associated with greater impulsivity in SDIs.
Participants were 100 currently abstinent, HIV seronegative male participants with history of substance
dependence, enrolled in a larger study of neurocognition and HIV among SDIs at the University of
Illinois, Chicago. Subjects testing positive on urine toxicology screening or breathalyzer testing for
alcohol, or with any history of potentially confounding neurologic illness or injury, schizophrenia, or
current alcohol abuse or dependence were excluded.
History of substance abuse and dependence was determined using the Structured Clinical Interview for
DSM-IVSubstanceAbuse Module(Firstetal., 1996). Antisocialitywas assessed bytheSocializationScale
of the California Psychological Inventory (So-CPI; Gough, 1987), a common measure of antisociality
among non-incarcerated individuals. We used the North American Adult Reading Test (Grober and
Sliwinski, 1991) to estimate verbal IQ.
All participants had a positive history of cocaine dependence and 80% carried a diagnosis of past
alcohol abuse or dependence. Subjects diagnosed additionally with opiate dependence (53% of the
sample) were classified as “high multidrug use”, while all others were assigned to the “low multidrug use”
group. Participants were further appointed to a “high” or “low antisocial” group based on a median split
(Md=27) of their So-CPI scores. With the exception of a positive hepatitis C serostatus [χ2=4.02,
Demographic and substance use characteristics
Y drug use
D last use
80 (31, 304)
21.31 (3.50 )
82.5 (36.5, 287)
115 (60.5, 195)
90 (30, 240)
So-CPI – Socialization Scale of the California Psychological Inventory; Y drug use – years of drug use; D last use – number of
days since last used drugs.
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pb0.04], the four groups were well matched on demographic and substance dependence characteristics
All subjects completed the computerized IGTand the Reaction Time (RT) Stroop Test (see Bechara et
al., 2001; Martin et al., 1992 for detailed descriptions). The IGTrequires subjects to select a series of cards
from one of four decks. Each card carries a monetary gain or loss of varying size. Patients with
ventromedial prefrontal lesions and SDIs often perform the task poorly, by persistently choosing cards
associated with large rewards but also with larger and more frequent losses. The computerized RT Stroop
requires subjects to name the display color of a series of colored words under three conditions with
varying demands on behavioral inhibition. The most taxing condition (i.e. the “incongruent condition”)
Fig. 2. Interaction between extent of multidrug use and trial block on the Iowa Gambling Task.
Fig. 1. Main effect of antisociality on Iowa Gambling Task.
3073J. Vassileva et al. / Addictive Behaviors 32 (2007) 3071–3076
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requires subjects to name color-discordant words (e.g. “RED” presented in green) while suppressing the
tendency to read the word.
IGT data were scored according to the procedure first reported by Bechara et al. (2001). Data were
analyzed with a mixed-model ANOVA, with trial block as the within-subject factor, and Multidrug Use
and Antisociality as the between-subjects factors. As expected, all groups improved their performance as
the task progressed [F(4,380)=10.93, pb0.0001]. However, contrary to expectations, higher levels of
antisociality were associated with better IGT performance overall [F(1,95)=5.17, pb0.02] (Fig. 1).
Additionally, IGTscores for subjects in the “low multidrug use” group showed a significant improvement
in performance over the 100 trials, whereas the subjects in the “high multidrug use” group showed no
evidence of improved performance as the task progressed, indicated by a significant interaction between
Trial Block and Multidrug Use [F(4,380)=2.77, pb0.02] (Fig. 2).
ANOVA.1All participants' reaction times increased with increasing demands on response inhibition [F
(2,158)=279.2; pb0.0001]. The “high multidrug use” group was significantly slower (M=814.95±21.19)
than the “low multidrug use” group (M=749.66±21.95) in all Stroop conditions [F(1,79)=4.58, pb0.03]
(Fig. 3); however, this group difference was no longer apparent when hepatitis C serostatus was controlled.
To our knowledge, this is the first study to investigate specifically the effects of antisociality and extent
of multidrug use on indices of impulsivity among SDIs. The study revealed three important findings. First
and foremost, contrary to predictions, we found that antisociality was associated with more advantageous
Fig. 3. Main effect of extent of multidrug use on the Stroop Color Word Task.
1Due to technical difficulties with the computer program, we had missing data from 18 subjects (valid n=88).
3074 J. Vassileva et al. / Addictive Behaviors 32 (2007) 3071–3076
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decision-making performance on the IGT and thus with better cognitive impulse control, independent of
extent of multidrug use. Second, there was indication of a significant improvement in decision-making
performance across IGT trial blocks for the low multidrug use but not for the high multidrug use group,
evidenced by a flatter learning curve in the high multidrug use group. Finally, greater extent of multidrug
usewas associatedwithgeneral psychomotor slowing,butnotwith motorimpulsivity perse on the Stroop
In light of our earlier finding that psychopathic heroin addicts evidence impaired performance on the
IGT (Vassileva et al., 2007), current results suggest that impaired performance of antisocial individuals on
the IGT may become evident only at the extreme end of the antisocial spectrum, when antisociality is a
clinically diagnosable syndrome such as Antisocial Personality Disorder or Psychopathy, and not when it
is manifested as a personality trait considered to be on a continuum with normality, such as degree of
socialization as assessed by the So-CPI. One might thus speculate that a sub-clinical, “non-malignant”
form of antisociality might exert a paradoxically facilitating effect on decision-making and cognitive
impulsivity in SDIs. This will have to be investigated further by future studies. Also, the fact that
antisociality had no effect on motor impulsivity indexed by the Stroop task, but in contrast had a
facilitating effect on decision-making/cognitive impulsivity may be related to better impulse control in the
antisocial group particularly when rewards are involved.
With regards to our second finding, the flatter learning curve of the high multidrug use SDIs suggests
that they do not learn the task contingencies and show greater tendency to perseverate on making
decisions that were initially rewarding, but ultimately disadvantageous. Relative to the high multidrug use
SDIs, our low multidrug use group was guided initially to a greater degree by the higher magnitude of the
immediate rewards. Yet, they learned to shift their strategy as soon as the first punishment trials were
delivered. In contrast, the high multidrug use subjects continued to be guided by the prospect of
immediate short-term gains, and never changed their selection strategy throughout the task.
Finally, the significance of the overall slowing in the high multidrug use group on the Stroop Task
remains unclear, because additional analyses revealed that differences in Stroop reaction times were found
to be accounted for by hepatitis C serostatus. This is consistent with a recent report from our laboratory
(Martin et al., 2004) indicating that a positive hepatitis C serostatus is associated with overall slower
information processing on the Stroop task, and deserves further investigation.
We thank Joanna Jacobus, Stephanie King, and Niles Rains for their assistance with data collection.
This research was supported by NIDA grants R21-DA18086 (JV), R01-DA12828 (EMM) and F32-
Bechara, A., Dolan, S., Denburg, N., Hindes, A., Anderson, S. W., & Nathan, P. E. (2001). Decision-making deficits, linked to a
dysfunctional ventromedial prefrontal cortex, revealed in alcohol and stimulant abusers. Neuropsychologia, 39, 376−389.
Craig, R. J. (2000). Prevalence of personality disorders among cocaine and heroin addicts. Substance Abuse, 21, 87−94.
Dougherty, D. M., Bjork, J. M., Harper, R. A., Marsh, D. M., Moeller, F. G., Mathias, C. W., et al. (2003). Behavioral impulsivity
paradigms: A comparison in hospitalized adolescents with disruptive behavior disorders. Journal of Child Psychology and
Psychiatry, 44, 1145−1157.
3075J. Vassileva et al. / Addictive Behaviors 32 (2007) 3071–3076
Author's personal copy Download full-text
First, M. B., Spitzer, R. L., Gibbon, M., & Williams, J. B. (1996). Structured clinical interview for DSM-IVAxis I disorders. New
York: Biometrics Research.
Goldstein, R. Z., & Volkow, N. D. (2002). Drug addiction and its underlying neurobiological basis: Neuroimaging evidence for
the involvement of the frontal cortex. American Journal of Psychiatry, 159, 1642−1652.
Gough, H. (1987). California psychological inventory administrator's guide. Palo Alto, CA: Consulting Psychologists Press.
Grober, E., & Sliwinski, M. (1991). Development and validation of a model for estimating premorbid verbal intelligence in the
elderly. Journal of Clinical and Experimental Neuropsychology, 13, 933−949.
Leri, F., Bruneau, J., & Stewart, J. (2003). Understanding polydrug use: Review of heroin and cocaine co-use. Addiction, 98,
Martin, E. M., Novak, R. M., Fendrich, M., Vassileva, J., Gonzalez, R., Grbesic, S., et al. (2004). Stroop performance in drug
users classified by HIV and hepatitis C virus serostatus. Journal of the International Neuropsychological Society, 10,
Martin, E. M., Robertson, L. C., Edelstein, H. E., Jagust, W. J., Sorensen, D. G., San Giovanni, D., et al. (1992). Performance of
patients with early HIV-1 infection on the Stroop Task. Journal of Clinical and Experimental Neuropsychology, 14, 857−858.
Mitchell, D., Colledge, G., Leonard, E., & Blair, A. (2002). Risky decisions and response reversal: Is there evidence of
orbitofrontal cortex dysfunction in psychopathic individuals? Neuropsychologia, 40, 2013−2022.
Moeller, G. F., Dougherty, D. M., Barratt, S. E., Oderinde, V., Mathias, C. W., Harper, R. A., et al. (2002). Increased impulsivity
in cocaine dependent subjects independent of antisocial personality disorder and aggression. Drug and Alcohol Dependence,
Vassileva, J., Petkova, P., Georgiev, S., Martin, E. M., Tersiyski, R., Raycheva, M., et al. (2007). Impaired decision-making in
psychopathic heroin addicts. Drug and Alcohol Dependence, 86, 287−289.
Verdejo-Garcia, A., & Perez-Garcia, M. (2007). Profile of executive deficits in cocaine and heroin polysubstance users: Common
and differential effects on separate executive components. Psychopharmacology, 190, 517−530.
3076J. Vassileva et al. / Addictive Behaviors 32 (2007) 3071–3076