In cocaine use disorders, deficits in working memory, disinhibition, decision making, and emotional processing persist at mid-term recovery; at long-term recovery, there are persistent deficits in flexibility and decision making. Methamphetamine is one of the more cognitively pervasive drugs, since deficits in episodic and working memory, disinhibition, and emotional processing persist at long-term recovery.
In the case of heavy MDMA (3,4-methylenedioxymethamphetamine) use, deficits in episodic and working memory, selective attention, and disinhibition may persist at mid-term recovery, whereas only mild deficits in episodic and working memory are manifest at long-term recovery. In heroin addiction, deficits in memory, attention, initiation of controlled response, disinhibition, and emotional process-ing persist at mid-term abstinence, and at long-term abstinence, working memory and decision-making skills are still significantly altered. Finally, with alcohol dependence, there are deficits in memory, selective attention, and emotional processing at mid-term abstinence and persistent deficits in visual-spatial skills and decision making at long-term abstinence.
Research on rehabilitation of cognitive deficits in addiction is in its infancy, but it seems clear that deficits in working memory, disinhibition, decision making, and emotional processing are by far the most significant and the most pervasive, so those should be our targets. As in other applications of neuropsychological rehabilitation, there are 2 complementary routes we can follow: attempt to restore these processes through intense stimulation, and attempt to compensate these deficits to optimize performance during activities of daily living.
The results of a recent study that applied cognitive stimulation of working memory functions in psychostimulant-dependent patients showed significant reductions of disinhibition (defined as decreased preference for small immediate rewards over more delayed ones) after 1 month of training.23 We used a holistic approach that combines Goal Management Training (GMT) for rehabilitation of executive functions with mindfulness meditation for training of emotional feedback relevant to focused attention and decision making.24 Our results showed significant improvements in working memory, disinhibition, and decision making after 7 weeks of treatment for mixed alcohol and cocaine polysubstance dependence.25
GMT relies on cognitive stimulation and promotion of treatment-relevant activities of daily living; therefore, it may constitute a more thorough and easy way to generalize intervention. Both studies support the feasibility of applying cognitive rehabilitation in patients with substance dependence. Another option is to adjust usual cognitive-behavioral interventions to the individual profile of cognitive dysfunction of each patient. For example, these interventions may consist of feedback-based learning rather than complex instructions in patients with attention/working memory problems or of compensation of disinhibition problems with community reinforcement approach strategies based on the achievement of delayed rewards. Clearly, future research is needed to support the long-term effectiveness of these interventions on clinical outcome variables (eg, craving, relapse); in the meantime, we have reasons to support the usefulness of a neuropsychological approach to problems of substance dependence.
1. Kalivas PW, Volkow ND. The neural basis of addiction: a pathology of motivation and choice. Am J Psychiatry. 2005;162:1403-1413.
2. Koob GF, Volkow ND. Neurocircuitry of addiction [published correction appears in Neuropsychopharmacology. 2010;35:1051]. Neuropsychopharmacology. 2010;35:217-238.
3. Fernández-Serrano MJ, Pérez-García M, Verdejo-García A. What are the specific vs. generalized effects of drugs of abuse on neuropsychological performance? Neurosci Biobehav Rev. 2011;35:377-406.
4. Fernández-Serrano MJ, Pérez-García M, Schmidt Río-Valle J, Verdejo-García A. Neuropsychological consequences of alcohol and drug abuse on different components of executive functions. J Psychopharmacol. 2010;24:1317-1332.
5. Verdejo-García A, Lawrence AJ, Clark L. Impulsivity as a vulnerability marker for substance-use disorders: review of findings from high-risk research, problem gamblers and genetic association studies. Neurosci Biobehav Rev. 2008;32:777-810.
6. Feil J, Sheppard D, Fitzgerald PB, et al. Addiction, compulsive drug seeking, and the role of frontostriatal mechanisms in regulating inhibitory control. Neurosci Biobehav Rev. 2010;35:248-275.
7. Belin D, Mar AC, Dalley JW, et al. High impulsivity predicts the switch to compulsive cocaine-taking. Science. 2008;320:1352-1355.
8. Kreek MJ, Nielsen DA, Butelman ER, LaForge KS. Genetic influences on impulsivity, risk taking, stress responsivity and vulnerability to drug abuse and addiction. Nat Neurosci. 2005;8:1450-1457.
9. Cherner M, Bousman C, Everall I, et al; HNRC Group. Cytochrome P450-2D6 extensive metabolizers are more vulnerable to methamphetamine-associated neurocognitive impairment: preliminary findings. J Int Neuropsychol Soc. 2010;16:890-901.
10. Verdejo-García A, Pérez-García M. Profile of executive deficits in cocaine and heroin polysubstance users: common and differential effects on separate executive components. Psychopharmacology (Berl). 2007;190:517-530.
11. Stuss DT, Alexander MP. Executive functions and the frontal lobes: a conceptual view. Psychol Res. 2000;63:289-298.
12. Robbins TW. Shifting and stopping: fronto-striatal substrates, neurochemical modulation and clinical implications. Philos Trans R Soc Lond B Biol Sci. 2007;362:917-932.
13. Ferníndez-Serrano MJ, Pérez-García M, Perales JC, Verdejo-García A. Prevalence of executive dysfunction in cocaine, heroin and alcohol users enrolled in therapeutic communities. Eur J Pharmacol. 2010;626:104-112.
14. Streeter CC, Terhune DB, Whitfield TH, et al. Performance on the Stroop predicts treatment compliance in cocaine-dependent individuals. Neuropsychopharmacology. 2008;33:827-836.
15. Turner TH, LaRowe S, Horner MD, et al. Measures of cognitive functioning as predictors of treatment outcome for cocaine dependence. J Subst Abuse Treat. 2009;37:328-334.
16. Passetti F, Clark L, Mehta MA, et al. Neuropsychological predictors of clinical outcome in opiate addiction. Drug Alcohol Depend. 2008;94:82-91.
17. Grace J, Malloy PF. Frontal Systems Behavior Scale (FrSBe): Professional Manual. Lutz, FL: Psychological Assessment Resources, Inc; 2001.
18. Verdejo-García A, Bechara A, Recknor EC, Pérez-García M. Executive dysfunction in substance dependent individuals during drug use and abstinence: an examination of the behavioral, cognitive and emotional correlates of addiction. J Int Neuropsychol Soc. 2006;12:405-415.
19. Frontal Systems Behavioral Scale (FrSBe). http://www.parinc.com. Accessed April 29, 2011.
20. Golden CJ. Stroop Color and Word Test Manual. Los Angeles: Western Psychological Services; 1978.
21. Kongs SK, Thompson LL, Iverson GL, Heaton RK. Wisconsin Card Sorting Test-64 Card Version: Professional Manual. Odessa, FL: Psychological Assessment Resources; 2000.
22. Bechara A. Iowa Gambling Task Professional Manual. Lutz, FL: Psychological Assessment Resources, Inc; 2001.
23. Bickel WK, Yi R, Landes RD, et al. Remember the future: working memory training decreases delay discounting among stimulant addicts. Biol Psychiatry. 2011;69:260-265.
24. Robertson IH, Levine B, Manly T. Goal Management Training. Toronto: Baycrest Rotman Research Institute; 2005.
25. Alfonso JP, Caracuel A, Delgado-Pastor LC, Verdejo-García A. Combined goal management training and mindfulness meditation improve executive functions and decision-making performance in abstinent polysubstance abusers. Drug Alcohol Depend. 2011 Jan 28; [Epub ahead of print].