Measures of cognitive functioning as predictors of treatment outcome for cocaine dependence

Predictors of cocaine use disorder treatment outcomes: a systematic review

BACKGROUND

Psychosocial approaches are the first-line treatments for cocaine dependence, although they still present high dropout and relapse rates. Thus, there is a pressing need to understand which variables influence treatment outcomes to improve current treatments and prevent dropout and relapse rates. The aim of this study is to explore predictors of treatment retention and abstinence in CUD.

METHODS

This systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We searched three databases-PubMed, PsychINFO and Web of Science-for randomized clinical trials (RCTs) published in English and Spanish from database inception through April 1, 2023. We selected all studies that met the inclusion criteria (adults aged ≥ 18, outpatient treatment, CUD as main addiction, and no severe mental illness) to obtain data for the narrative synthesis addressing cocaine abstinence and treatment retention as main outcome variables. After data extraction was completed, risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (RoB-2).

RESULTS

A total of 566 studies were screened, and, of those, 32 RCTs were included in the synthesis. Younger age, more years of cocaine use, and craving levels were significant predictors of relapse and treatment dropout. Fewer withdrawal symptoms, greater baseline abstinence, greater treatment engagement, and more self-efficacy were all predictors of longer duration of abstinence. The role of impulsivity as a predictor of CUD is unclear due to conflicting data, although the evidence generally suggests that higher impulsivity scores can predict more severe addiction and withdrawal symptoms, and earlier discontinuation of treatment.

CONCLUSION

Current evidence indicates which variables have a direct influence on treatment outcomes, including well-studied cocaine use-related variables. However, additional variables, such as genetic markers, appear to have a high impact on treatment outcomes and need further study.

SYSTEMATIC REVIEW REGISTRATION

This systematic review is registered at PROSPERO (ID: CRD42021271847). This study was funded by the Spanish Ministry of Science, Innovation and Universities, Instituto Carlos III (ISCIII) (FIS PI20/00929) and FEDER funds and Fundació Privada Hospital de la Santa Creu i Sant Pau (Pla d'acció social 2020).

Association Between Inflammatory Cytokines, Executive Function, and Substance Use in Patients With Opioid Use Disorder and Amphetamine-Type Stimulants Use Disorder

BACKGROUND

Long-term opioid and amphetamine-type stimulants (ATS) abuse may affect immunological function and impair executive function. We aimed to determine whether biomarkers of inflammation and executive function were associated with substance use in individuals with opioid use disorder (OUD) and ATS use disorder (ATSUD). The interactions between these biomarkers were also explored.

METHODS

We assessed plasma cytokines [tumor necrosis factor (TNF)-α, C-reactive protein (CRP), interleukin (IL)-8, IL-6, transforming growth factor (TGF)-β1, brain-derived neurotrophic factor (BDNF), and executive function in terms of the Wisconsin Card Sorting Test (WCST) and Continuous Performance Test (CPT) in OUD and ATSUD patients and healthy controls (HC). OUD and ATSUD patients were followed for 12 weeks, and their urine morphine and amphetamine tests, cytokine levels, and executive function were repeatedly measured.

RESULTS

We enrolled 483 patients and 145 HC. Plasma TNF-α, CRP, IL-8, IL-6, and BDNF levels and most subscale scores on the WCST and CPT significantly differed between OUD and ATSUD patients and HC. Increased TNF-α levels and more perseveration error on the WCST were significantly associated with more urine drug-positive results and less abstinence. Plasma IL-6 and CRP levels were significantly negatively correlated with WCST and CPT performance.

CONCLUSION

OUD and ATSUD patients had more inflammation and worse executive function than HC. Inflammatory markers and WCST performance were associated with their urinary drug results, and higher inflammation was associated with poor executive function. Studies on regulating the inflammatory process and enhancing executive function in OUD and ATSUD are warranted.

Noninvasive Brain Stimulation Rescues Cocaine-Induced Prefrontal Hypoactivity and Restores Flexible Behavior

BACKGROUND

To obtain desirable goals, individuals must predict the outcome of specific choices, use that information to direct appropriate actions, and adjust behavior accordingly in changing environments (behavioral flexibility). Substance use disorders are marked by impairments in behavioral flexibility along with decreased prefrontal cortical function that limits the efficacy of treatment strategies. Restoring prefrontal hypoactivity, ideally in a noninvasive manner, is an intriguing target for improving flexible behavior and treatment outcomes.

METHODS

A behavioral flexibility task was used in Long-Evans male rats (n = 97) in conjunction with electrophysiology, optogenetics, and a novel rat model of transcranial alternating current stimulation (tACS) to examine the prelimbic cortex (PrL) to nucleus accumbens (NAc) core circuit in behavioral flexibility and determine whether tACS can restore cocaine-induced neural and cognitive dysfunction.

RESULTS

Optogenetic inactivation revealed that the PrL-NAc core circuit is necessary for the ability to learn strategies to flexibly shift behavior. Cocaine self-administration history caused aberrant PrL-NAc core neural encoding and deficits in flexibility. Optogenetics that selectively activated the PrL-NAc core pathway prior to learning rescued cocaine-induced cognitive flexibility deficits. Remarkably, tACS prior to learning the task reestablished adaptive signaling in the PrL-NAc circuit and restored flexible behavior in a relatively noninvasive and frequency-specific manner.

CONCLUSIONS

We establish a role of NAc core-projecting PrL neurons in behavioral flexibility and provide a novel noninvasive brain stimulation method in rats to rescue cocaine-induced frontal hypofunction and restore flexible behavior, supporting a role of tACS as a therapeutic to treat cognitive deficits in substance use disorders.

Deficits in recognizing female facial expressions related to social network in cocaine-addicted men

BACKGROUND

The ability to accurately recognise facial expressions of emotion is crucial for social functioning and maintaining healthy relationships. Recognising the emotional state of others allows us to respond to their needs and adjust our behaviour appropriately. Impairments in facial affect recognition have been reported in chronic cocaine users but little is known whether these contribute to their difficulties in social situations.

METHODS

We assessed facial emotional expression recognition in forty-five men with cocaine use disorder (CUD) and forty-four healthy control participants. Using standardised questionnaires, we also collected information on perceived social support, social provision and community integration.

RESULTS

Our results found that male cocaine users had greater difficulty in recognising female emotional facial expressions than male controls. This effect was not explained by demographic variables but it was associated with their social network; including social support, social provisions and community integration.

CONCLUSION

Our findings suggest that men with CUD have greater difficulty in identifying emotional expression in female faces, which is linked with their social support networks. This may play an important role in misunderstanding non-verbal communications that contribute to destabilising friendship and family ties typically seen in drug addiction. Addressing deficits in recognising female emotional expressions may be an important piece of information for counselling and other interventions.

Probabilistic Reversal Learning Deficits in Patients With Methamphetamine Use Disorder-A Longitudinal Pilot Study

Methamphetamine use disorder (MUD) is increasing worldwide and commonly associated with learning deficits. Little is known the about underlying trajectories, i.e., how the affected higher-order cognitive functions develop over time and with respect to abstinence and relapse. A probabilistic reversal learning (PRL) paradigm was implemented to uncover the microstructure of impulsive choice and maladaptive learning strategies in 23 patients with MUD in comparison with 24 controls. Baseline data revealed fewer optimal choices and a pattern of altered learning behavior from negative and positive feedback in patients suggesting impairments in flexibly-adapting behavior to changes of reward contingencies. Integrating longitudinal data from a follow-up assessment after 3 months of specific treatment revealed a group-by-time interaction indicating a normalization of these cognitive impairments in patients with MUD. In summary, our study demonstrates behavioral correlates of maladaptive decision-making processes in patients with MUD, which may recover after 3 months of MUD-specific therapy paving the way for further learning-based interventions. Limited by a small sample size, the results of this pilot study warrant replication in larger populations.

Tonic exploration governs both flexibility and lapses

In many cognitive tasks, lapses (spontaneous errors) are tacitly dismissed as the result of nuisance processes like sensorimotor noise, fatigue, or disengagement. However, some lapses could also be caused by exploratory noise: randomness in behavior that facilitates learning in changing environments. If so, then strategic processes would need only up-regulate (rather than generate) exploration to adapt to a changing environment. This view predicts that more frequent lapses should be associated with greater flexibility because these behaviors share a common cause. Here, we report that when rhesus macaques performed a set-shifting task, lapse rates were negatively correlated with perseverative error frequency across sessions, consistent with a common basis in exploration. The results could not be explained by local failures to learn. Furthermore, chronic exposure to cocaine, which is known to impair cognitive flexibility, did increase perseverative errors, but, surprisingly, also improved overall set-shifting task performance by reducing lapse rates. We reconcile these results with a state-switching model in which cocaine decreases exploration by deepening attractor basins corresponding to rule states. These results support the idea that exploratory noise contributes to lapses, affecting rule-based decision-making even when it has no strategic value, and suggest that one key mechanism for regulating exploration may be the depth of rule states.

Effects of chronic cocaine self-administration and N-acetylcysteine on learning, cognitive flexibility, and reinstatement in nonhuman primates

RATIONALE

Cocaine use disorder (CUD) is associated with cognitive deficits that have been linked to poor treatment outcomes. An improved understanding of cocaine's deleterious effects on cognition may help optimize pharmacotherapies. Emerging evidence implicates abnormalities in glutamate neurotransmission in CUD and drugs that normalize glutamatergic homeostasis (e.g., N-acetylcysteine [NAC]) may attenuate CUD-related relapse behavior.

OBJECTIVES

The present studies examined the impact of chronic cocaine exposure on touchscreen-based models of learning (repeated acquisition) and cognitive flexibility (discrimination reversal) and, also, the ability of NAC to modulate cocaine self-administration and its capacity to reinstate drug-seeking behavior.

METHODS

First, stable repeated acquisition and discrimination reversal performance was established. Next, high levels of cocaine-taking behavior (2.13-3.03 mg/kg/session) were maintained for 150 sessions during which repeated acquisition and discrimination reversal performance was probed periodically. Finally, the effects of NAC treatment were examined on cocaine self-administration and, subsequently, extinction and reinstatement.

RESULTS

Cocaine self-administration significantly impaired performance under both cognitive tasks; however, discrimination reversal was disrupted considerably more than acquisition. Performance eventually approximated baseline levels during chronic exposure. NAC treatment did not perturb ongoing self-administration behavior but was associated with significantly quicker extinction of drug-lever responding. Cocaine-primed reinstatement did not significantly differ between groups.

CONCLUSIONS

The disruptive effects of cocaine on learning and cognitive flexibility are profound but performance recovered during chronic exposure. Although the effects of NAC on models of drug-taking and drug-seeking behavior in monkeys are less robust than reported in rodents, they nevertheless suggest a role for glutamatergic modulators in CUD treatment programs.

Cognitive dysfunction in individuals with cocaine use disorder: Potential moderating factors and pharmacological treatments

It is well-documented in the literature that individuals repeatedly exposed to cocaine exhibit cognitive impairment and that cognitive dysfunction is a risk factor for poor treatment outcomes in those with cocaine use disorder (CUD). Specific deficits related to attention, episodic memory, working memory, and executive functioning are the most common deficits noted in this population. Given that cognitive impairment is a risk factor for poor treatment outcomes in those with CUD, identifying possible moderating factors contributing to and/or exacerbating cocaine-related cognitive deficits is of great importance. Some of these factors may include premorbid intellectual functioning, cocaine use patterns, polysubstance use, comorbid emotional symptoms, and sleep dysfunction. It is plausible that by identifying moderating factors impacting cognition, behavioral interventions can then be modified accordingly and/or treatment regimens can be augmented with pharmacological interventions (e.g., cognitive enhancing agents), leading to a reduction in treatment attrition and improved treatment outcomes. The currently available treatments for CUD are mainly behavioral with variable efficacy, and even though there have been great preclinical and clinical research efforts focused on medication development for CUD, there are currently no Food and Drug Administration-approved medications for CUD. A description of some of the several potential moderating factors, along with some pharmacological treatments which have been shown to ameliorate, at least to some extent, cognitive dysfunction in those with CUD are discussed. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The role of neurocognitive functioning, substance use variables and the DSM-5 severity scale in cocaine relapse: A prospective study

BACKGROUND

The severity of substance use disorder (SUD) is currently defined by the sum of DSM-5 criteria. However, little is known about the validity of this framework or the role of additional severity indicators in relapse prediction. This study aimed to investigate the relationship between DSM-5 criteria, neurocognitive functioning, substance use variables and cocaine relapse among inpatients with cocaine use disorder (CUD).

METHODS

128 adults aged between 18 and 45 years were evaluated; 68 (59 males, 9 females) had CUD and 60 (52 males, 8 females) were healthy controls. For the group with CUD, the use of other substances was not an exclusion criterion. Participants were tested using a battery of neurocognitive tests. Cocaine relapse was evaluated 3 months after discharge.

RESULTS

Scores for attention span and working memory were worse in patients compared to controls. Earlier onset and duration of cocaine use were related to poorer inhibitory control and global executive functioning, respectively; recent use was related to worse performance in inhibitory control, attention span and working memory. More DSM-5 criteria at baseline were significantly associated with relapse.

CONCLUSIONS

Recent cocaine use was the most predictive variable for neurocognitive impairments, while DSM-5 criteria predicted cocaine relapse at three months post treatment. The integration of neurocognitive measures, DSM-5 criteria and cocaine use variables in CUD diagnosis could improve severity differentiation. Longitudinal studies using additional biomarkers are needed to disentangle the different roles of severity indicators in relapse prediction and to achieve more individualized and effective treatment strategies for these patients.

A Patient-Tailored Evidence-Based Approach for Developing Early Neuropsychological Training Programs in Addiction Settings

Substance use disorders (SUDs) are associated with impairments of cognitive functions, and cognitive training programs are thus rapidly developing in SUD treatment. However, neuropsychological impairments observed early after withdrawal (i.e., early impairments), that is, approximately in the first six months, may be widespread. Consequently, it might not be possible to train all the identified early impairments. In these situations, we propose that the priority of cognitive training should be given to the early impairments found to be associated with early dropout or relapse (i.e., relapse-related impairments). However, substance-specific relapse-related impairments have not been singled out among all early impairments so far. Using a systematic literature search, we identified the types of established early impairments for all SUDs, and we assessed the extent to which these early impairments were found to be associated with relapse-related impairments. All cognitive functions were investigated according to a classification based on current neuropsychological models, distinguishing classical cognitive, substance-bias, and social cognition systems. According to the current evidence, demonstrated relapse-related impairments in alcohol use disorder comprised impulsivity, long-term memory, and higher-order executive functions. For cannabis use disorder, the identified relapse-related impairments were impulsivity and working memory. For stimulant use disorder, the identified relapse-related impairments were attentional abilities and higher-order executive functions. For opioid use disorder, the only identified relapse-related impairments were higher executive functions. However, many early impairments were not explored with respect to dropout/relapse, particularly for stimulant and opioid use disorders. The current literature reveals substance-specific relapse-related impairments, which supports a pragmatic patient-tailored approach for defining which early impairments should be prioritized in terms of training among patients with SUDs.

Prefrontal-accumbens opioid plasticity: Implications for relapse and dependence

In addiction, an individual's ability to inhibit drug seeking and drug taking is thought to reflect a pathological strengthening of drug-seeking behaviors or impairments in the capacity to control maladaptive behavior. These processes are not mutually exclusive and reflect drug-induced modifications within prefrontal cortical and nucleus accumbens circuits, however unlike psychostimulants such as cocaine, far less is known about the temporal, anatomical, and cellular dynamics of these changes. We discuss what is known regarding opioid-induced adaptations in intrinsic membrane physiology and pre-/postsynaptic neurotransmission in principle pyramidal and medium spiny neurons in the medial prefrontal cortex and nucleus accumbens from electrophysiological studies and explore how circuit specific adaptations may contribute to unique facets of opioid addiction.

Modified cognitive behavioral therapy (M-CBT) for cocaine dependence: Development of treatment for cognitively impaired users and results from a Stage 1 trial

Cognitive impairments are associated with poor outcomes when treating cocaine dependent patients, but behavioral interventions to mitigate this impact have not been developed. In this Stage 1A/1B treatment development study, several compensatory strategies (e.g., content repetition, daily logs, diaries, visual presentation) were combined to create a modified cognitive behavioral therapy (M-CBT) for treating cocaine dependence. Initially, a select group of therapists, neuropsychology experts, and patients were asked to provide input on early drafts of the treatment manual and companion patient workbook. After an uncontrolled small trial (N = 15) and two rounds of manual development (Stage 1A), a pilot randomized clinical trial (N = 102) of cocaine dependent outpatients with and without cognitive impairments was conducted (Stage 1B). Participants were randomized to M-CBT (N = 52) or CBT (N = 50). Both treatments were individually delivered over 12 weeks with assessments conducted at baseline, end-of-treatment, and 3-month follow-up. The primary outcome was frequency of cocaine use, measured by number of days used in the prior 7 days. Participants in the two treatment groups did not differ significantly on drug use reduction or retention in treatment. However, among participants who completed at least 9 weeks of treatment, those in M-CBT showed a trend toward greater reduction in cocaine use compared to those in the CBT group. M-CBT is feasible for impaired and nonimpaired cocaine dependent participants. However, M-CBT treatment did not show significant superiority over standard CBT in the present sample. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Let's Open the Decision-Making Umbrella: A Framework for Conceptualizing and Assessing Features of Impaired Decision Making in Addiction

Decision-making impairments play a pivotal role in the emergence and maintenance of addictive disorders. However, a sound conceptualization of decision making as an umbrella construct, encompassing its cognitive, affective, motivational, and physiological subcomponents, is still lacking. This prevents an efficient evaluation of the heterogeneity of decision-making impairments and the development of tailored treatment. This paper thus unfolds the various processes involved in decision making by adopting a critical approach of prominent dual- or triadic-process models, which postulate that decision making is influenced by the interplay of impulsive-automatic, reflective-controlled, and interoceptive processes. Our approach also focuses on social cognition processes, which play a crucial role in decision making and addictive disorders but were largely ignored in previous dual- or triadic-process models. We propose here a theoretical framework in which a range of coordinated processes are first identified on the basis of their theoretical and clinical relevance. Each selected process is then defined before reviewing available results underlining its role in addictive disorders (i.e., substance use, gambling, and gaming disorders). Laboratory tasks for measuring each process are also proposed, initiating a preliminary process-based decision-making assessment battery. This original approach may offer an especially informative view of the constitutive features of decision-making impairments in addiction. As prior research has implicated these features as risk factors for the development and maintenance of addictive disorders, our processual approach sets the scene for novel and transdiagnostic experimental and applied research avenues.

White matter integrity between left basal ganglia and left prefrontal cortex is compromised in gambling disorder

Pathological gambling (PG) is a behavioral addiction characterized by an inability to stop gambling despite the negative consequences, which may be mediated by cognitive flexibility deficits. Indeed, impaired cognitive flexibility has previously been linked to PG and also to reduced integrity of white matter connections between the basal ganglia and the prefrontal cortex. It remains unclear, however, how white matter integrity problems relate to cognitive inflexibility seen in PG. We used a cognitive switch paradigm during functional magnetic resonance imaging in pathological gamblers (PGs; n = 26) and healthy controls (HCs; n = 26). Cognitive flexibility performance was measured behaviorally by accuracy and reaction time on the switch task, while brain activity was measured in terms of blood oxygen level-dependent responses. We also used diffusion tensor imaging on a subset of data (PGs = 21; HCs = 21) in combination with tract-based spatial statistics and probabilistic fiber tracking to assess white matter integrity between the basal ganglia and the dorsolateral prefrontal cortex. Although there were no significant group differences in either task performance, related neural activity or tract-based spatial statistics, PGs did show decreased white matter integrity between the left basal ganglia and prefrontal cortex. Our results complement and expand similar findings from a previous study in alcohol-dependent patients. Although we found no association between white matter integrity and task performance here, decreased white matter connections may contribute to a diminished ability to recruit prefrontal networks needed for regulating behavior in PG. Hence, our findings could resonate an underlying risk factor for PG, and we speculate that these findings may extend to addiction in general.

Factors associated with attrition in substance using patients enrolled in an intensive outpatient program

BACKGROUND AND OBJECTIVES

Data suggest individuals with substance use disorders (SUD) have high rates of attrition from treatment and exhibit impairments on measures of executive functioning (EF). The primary aim of this pilot study was to investigate if EF is associated with attrition from a 1 month intensive outpatient program (IOP) for SUD, and examine the feasibility of implementing the project.

METHODS

Baseline neurocognitive functioning was assessed by the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the self-reported Behavior Rating Inventory of Executive Functioning (BRIEF-A) questionnaire.

RESULTS

Thirty subjects enrolled in the pilot study: including 20 "completers" (age 39.5 ± 13.1 years) and 10 "drop-outs" who discontinued the IOP prior to completion (age 32 ± 11.1 years). IOP drop-out was associated with earlier age of substance use onset (all p-values <0.05) and male gender, as well as greater SUD, opiate use, and past week substance use. Overall a high level of executive dysfunction was found on the BRIEF-A and CANTAB assessments, and specific differences emerged between completers and drop outs. However, no statistically significant differences were found between these groups on measures of depression, anxiety, or ADHD.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Overall, findings from this pilot study suggest high levels of self-reported executive dysfunction, but EF's predictive association with drop-out was limited. Measures of addiction severity were more strongly associated with attrition, suggesting potential utility of brief motivational interventions prior to commencing an IOP may improve retention. Further investigations with larger and more diverse samples are warranted. (Am J Addict 2017;26:780-787).

Attention and memory deficits in crack-cocaine users persist over four weeks of abstinence

BACKGROUND

Crack-cocaine addiction is an important public health problem worldwide. Although there is not a consensus, preliminary evidence has suggested that cognitive impairments in patients with crack-cocaine dependence persist during abstinence, affecting different neuropsychological domains. However, few studies have prospectively evaluated those deficits in different phases of abstinence.

OBJECTIVES

The main aim of present study was to examine neuropsychological performance of patients with crack-cocaine dependence during early abstinence and after four weeks, comparing with matched controls.

METHODS

Thirty-five males with crack-cocaine dependence, aged 18 to 50years, who met DSM-IV criteria for cocaine dependence and a control group of 33 healthy men were enrolled. They were assessed through Block Design, Digit Span and Vocabulary of Wechsler Adult Intelligence Scale (WAIS-III), the Rey Auditory Learning Test (RAVLT) and the Verbal Fluency (FAS) between 3 and 10days (mean of 6.1±2.0days) and after 4weeks of abstinence.

RESULTS

Compared to controls, the crack-cocaine dependent group exhibited deficits in cognitive performance affecting attention, verbal memory and learning tasks in early withdrawal. Most of the cognitive deficits persisted after four weeks of abstinence.

CONCLUSION

Present results observed that the group of patients with crack-cocaine dependence presented persistent deficits affecting memory and attention even after four weeks of abstinence, confirming previous studies that had disclosed such cognitive impairments.

Impact of general cognition and executive function deficits on addiction treatment outcomes: Systematic review and discussion of neurocognitive pathways

This systematic review aims to examine growing evidence linking cognitive-executive functions with addiction treatment outcomes, and to discuss significant cognitive predictors drawing upon addiction neuroscience theory. We conducted a systematic search to identify studies using measures of general cognition and executive functions in patients with substance use disorders for the purpose of predicting two treatment outcomes: therapeutic adherence and relapse. Forty-six studies were selected, and sample characteristics, timing of assessments, and cognitive measures were analyzed. We observed significant methodological differences across studies, resulting in substantial variability in the relationships between cognitive-executive domains and treatment outcomes. Notwithstanding this variability, we found evidence of associations, of medium effect size, between general cognition and treatment adherence, and between reward-based decision-making and relapse. The link between general cognition and treatment adherence is consistent with emerging evidence linking limited cognitive-executive resources with less ability to benefit from talk therapies. The link between reward-based decision-making and relapse accords with decision neuroscience models of addiction. Findings may inform preclinical and clinical research concerning addiction treatment mechanisms.

Performance-Based Contingency Management in Cognitive Remediation Training: A Pilot Study

Impairments in attention, working memory, and executive function are common among substance users and may adversely affect SUD treatment outcomes. The ability of cognitive remediation (CR) interventions to improve these deficits is hindered in part because levels of engagement in CR training may be inadequate to achieve benefit. This pilot study aimed to increase CR engagement and improve outcome by implementing contingency management (CM) procedures that reinforce performance improvements on CR tasks. Participants were forty individuals (50% male; 65% African American) in an outpatient substance use treatment facility with mild cognitive impairment who had ≥30-days of abstinence from alcohol and drugs. They were randomized to standard (CR-S; n=21) or CM-enhanced (CR-CM; n=19) cognitive remediation training. CR consisted of 1-hour sessions, three times per week for four weeks (12 sessions). A neuropsychological assessment battery was administered prior to and after the four-week intervention. Both groups had high rates of CR session attendance (mean CR-S=11.7, CR-CM=10.9 sessions). Performance on 8 of the 9 CR tasks significantly improved over time for both conditions, with the CR-CM condition demonstrating greater improvement on a CR Sequenced Recall task [F(1,37)=5.81, p<.05]. Significant improvement was also evident on 4 of 9 neuropsychological assessment measures, with the CR-CM condition showing differential improvement on the Trail Making Test - Part B [F (1,37)=5.34, p<.05]. These findings support the feasibility of using CM procedures to enhance substance users' engagement with CR training and suggest the potential value of more research in this area.

Association between motor timing and treatment outcomes in patients with alcohol and/or cocaine use disorder in a rehabilitation program

BACKGROUND

Individuals with Substance Use Disorders (SUDs) have disruptions in the brain's dopaminergic (DA) system and the functioning of its target neural substrates (striatum and prefrontal cortex). These substrates are important for the normal processing of reward, inhibitory control and motivation. Cognitive deficits in attention, impulsivity and working memory have been found in individuals with SUDs and are predictors of poor SUD treatment outcomes and relapse in alcohol and cocaine dependence specifically. Furthermore, the DA system and accompanying neural substrates play a key role in the timing of motor acts (motor timing). Motor timing deficits have been found in DA system related disorders and more recently also in individuals with SUDs. Motor timing is found to correlate with attention, impulsivity and working memory deficits. To our knowledge motor timing, with regards to treatment outcome and relapse, has not been investigated in populations with SUDs.

METHODS/DESIGN

This study aims to investigate motor timing and its relation to treatment response (at 8 weeks) and relapse (at 12 months) in cocaine and/or alcohol dependent individuals. The tested sensitivity values of motor timing parameters will be compared to a battery of neurocognitive tests, owing to the novelty of the motor task battery, the confounding effects of attention and working memory on motor timing paradigms, and high impulsivity levels found in individuals with SUDs.

DISCUSSION

This research will contribute to current knowledge of neuropsychological deficits associated with treatment response in SUDs and possibly provide an opportunity to individualize and modify currently available treatments through the possible prognostic value of motor task performance in cocaine and/or alcohol dependent individuals.

Health-Related Decision-Making in HIV Disease

Individuals living with HIV show moderate decision-making deficits, though no prior studies have evaluated the ability to make optimal health-related decisions across the HIV healthcare continuum. Forty-three HIV+ individuals with HIV-associated neurocognitive disorders (HAND+), 50 HIV+ individuals without HAND (HAND-), and 42 HIV- participants were administered two measures of health-related decision-making as part of a comprehensive neuropsychological battery: (1) The Decisional Conflict Scale (DCS), and (2) The Modified UCSD Brief Assessment for Capacity to Consent (UBACC-T). Multiple regression analyses revealed that HAND was an independent predictor of both the DCS and the UBACC-T, such that the HAND+ sample evidenced significantly poorer scores relative to comparison groups. Within the HIV+ sample, poorer health-related decision-making was associated with worse performance on tests of episodic memory, risky decision-making, and health literacy. Findings indicate that individuals with HAND evidence moderate deficits in effectively comprehending and evaluating various health-related choices.

Decision-making processes as predictors of relapse and subsequent use in stimulant-dependent patients

BACKGROUND

Decision-making processes have been posited to affect treatment outcome in addicted patients.

OBJECTIVE

The present multi-site study assessed whether two measures of decision-making predicted relapse and subsequent use in stimulant-dependent patients.

METHODS

A total of 160 methamphetamine- or cocaine-dependent patients participating in a multi-site clinical trial evaluating a modified 12-step facilitation intervention for stimulant-dependent patients (STAGE-12) were assessed. Decision-making processes of risk and delay (Iowa Gambling Task [IGT]) and response reversal (Wisconsin Card Sorting Task [WCST]) were obtained shortly after treatment admission followed by assessment of stimulant use over the next six months. The relationships of the IGT and WCST (Perseverative Errors) with relapse (yes/no) and days of stimulant use during the 6-month period following post-randomization were evaluated.

RESULTS

Performance on the IGT and WCST did not significantly predict relapse status or time to relapse. Unexpectedly, worse performance on the IGT was associated with a fewer number of stimulant use days (p = 0.001). In contrast, worse performance on the WCST (more perseverative errors) was associated with a greater number of stimulant use days (p = 0.0003). The predictive effects of perseverative errors on subsequent use were confined to methamphetamine-dependent and Minority participants.

CONCLUSIONS

Decision-making processes, as measured in the current study, do not uniformly predict relapse or subsequent use. A decrease in the salience attribution of non-drug reinforcers may explain the positive relationship between IGT performance and post-relapse use. More comprehensive and global measures of impulsiveness may better assess relapse risk and use.

Cognitive Function as a Transdiagnostic Treatment Target in Stimulant Use Disorders

Stimulant use disorder is an important public health problem, with an estimated 2.1 million current users in the United States alone. No pharmacological treatments are approved by the U.S. Food and Drug Administration for stimulant use disorder and behavioral treatments have variable efficacy and limited availability. Most individuals with stimulant use disorder have other comorbidities, most with overlapping symptoms and cognitive impairments. The goal of this article is to present a rationale for cognition as a treatment target in stimulant use disorder and to outline potential treatment approaches. Rates of lifetime comorbid psychiatric disorders among people with stimulant use disorders are estimated at 65% to 73%, with the most common being mood disorders (13% to 64%) and anxiety disorders (21% to 50%), as well as non-substance-induced psychotic disorders (<10%). There are several models of addictive behavior, but the dual process model particularly highlights the relevance of cognitive impairments and biases to the development and maintenance of addiction. This model explains addictive behavior as a balance between automatic processes and executive control, which in turn are related to individual (genetics, comorbid disorders, psychosocial factors) and other (craving, triggers, drug use) factors. Certain cognitive impairments, such as attentional bias and approach bias, are most relevant to automatic processes, while sustained attention, response inhibition, and working memory are primarily related to executive control. These cognitive impairments and biases are also common in disorders frequently comorbid with stimulant use disorder and predict poor treatment retention and clinical outcomes. As such, they may serve as feasible transdiagnostic treatment targets. There are promising pharmacological, cognitive, and behavioral approaches that aim to enhance cognitive function. Pharmacotherapies target cognitive impairments associated with executive control and include cholinesterase inhibitors (e.g., galantamine, rivastigmine) and monoamine transporter inhibitors (e.g., modafinil, methylphenidate). Cognitive behavioral therapy and cognitive rehabilitation also enhance executive control, while cognitive bias modification targets impairments associated with automatic processes. Cognitive enhancement to improve treatment outcomes is a novel and promising strategy, but its clinical value for the treatment of stimulant use disorder, with or without other psychiatric comorbidities, remains to be determined in future studies.

A randomized controlled trial of the effects of working memory training in methadone maintenance patients

OBJECTIVE

Working memory impairment in individuals with chronic opioid dependence can play a major role in cognitive and treatment outcomes. Cognitive training targeting working memory shows promise for improved function in substance use disorders. To date, cognitive training has not been incorporated as an adjunctive treatment for opioid dependence.

METHODS

Methadone maintenance patients were randomly assigned to experimental (n=28) or active control (n=28) 25-session computerized training and run in parallel. Cognitive and drug use outcomes were assessed before and after training.

RESULTS

Participants in the experimental condition showed performance improvements on two of four working memory measures, and both groups improved on a third measure of working memory performance. Less frequent drug use was found in the experimental group than in the control group post-training. In contrast to previous findings with stimulant users, no significant effect of working memory training on delay discounting was found using either hypothetical or real rewards. There were no group differences on working memory outcome measures that were dissimilar from the training tasks, suggesting that another mechanism (e.g., increased distress tolerance) may have driven drug use results.

CONCLUSIONS

Working memory training improves performance on some measures of working memory in methadone maintenance patients, and may impact drug use outcomes. Working memory training shows promise in patients with substance use disorders; however, further research is needed to understand the mechanisms through which performance is improved and drug use outcomes are impacted.

Neural substrates of cognitive flexibility in cocaine and gambling addictions

BACKGROUND

Individuals with cocaine and gambling addictions exhibit cognitive flexibility deficits that may underlie persistence of harmful behaviours.

AIMS

We investigated the neural substrates of cognitive inflexibility in cocaine users v. pathological gamblers, aiming to disambiguate common mechanisms v. cocaine effects.

METHOD

Eighteen cocaine users, 18 pathological gamblers and 18 controls performed a probabilistic reversal learning task during functional magnetic resonance imaging, and were genotyped for the DRD2/ANKK Taq1A polymorphism.

RESULTS

Cocaine users and pathological gamblers exhibited reduced ventrolateral prefrontal cortex (PFC) signal during reversal shifting. Cocaine users further showed increased dorsomedial PFC (dmPFC) activation relative to pathological gamblers during perseveration, and decreased dorsolateral PFC activation relative to pathological gamblers and controls during shifting. Preliminary genetic findings indicated that cocaine users carrying the DRD2/ANKK Taq1A1+ genotype may derive unique stimulatory effects on shifting-related ventrolateral PFC signal.

CONCLUSIONS

Reduced ventrolateral PFC activation during shifting may constitute a common neural marker across gambling and cocaine addictions. Additional cocaine-related effects relate to a wider pattern of task-related dysregulation, reflected in signal abnormalities in dorsolateral and dmPFC.

Cocaine use severity and cerebellar gray matter are associated with reversal learning deficits in cocaine-dependent individuals

Cocaine addiction involves persistent deficits to unlearn previously rewarded response options, potentially due to neuroadaptations in learning-sensitive regions. Cocaine-targeted prefrontal systems have been consistently associated with reinforcement learning and reversal deficits, but more recent interspecies research has raised awareness about the contribution of the cerebellum to cocaine addiction and reversal. We aimed at investigating the link between cocaine use, reversal learning and prefrontal, insula and cerebellar gray matter in cocaine-dependent individuals (CDIs) varying on levels of cocaine exposure in comparison with healthy controls (HCs). Twenty CDIs and 21 HCs performed a probabilistic reversal learning task (PRLT) and were subsequently scanned in a 3-Tesla magnetic resonance imaging scanner. In the PRLT, subjects progressively learn to respond to one predominantly reinforced stimulus, and then must learn to respond according to the opposite, previously irrelevant, stimulus-reward pairing. Performance measures were errors after reversal (reversal cost), and probability of maintaining response after errors. Voxel-based morphometry was conducted to investigate the association between gray matter volume in the regions of interest and cocaine use and PRLT performance. Severity of cocaine use correlated with gray matter volume reduction in the left cerebellum (lobule VIII), while greater reversal cost was correlated with gray matter volume reduction in a partially overlapping cluster (lobules VIIb and VIII). Right insula/inferior frontal gyrus correlated with probability of maintaining response after errors. Severity of cocaine use detrimentally impacted reversal learning and cerebellar gray matter.

Guanfacine enhances inhibitory control and attentional shifting in early abstinent cocaine-dependent individuals

OBJECTIVES

Attenuation of adrenergic drive and cognitive enhancement, via stimulation of alpha2 pre- and post-synaptic receptors, may selectively enhance executive performance in early abstinent cocaine-dependent individuals. As these cognitive processes underpin important treatment-related behaviors, the alpha2 agonist, guanfacine HCl, may represent an effective pharmaco-therapeutic intervention.

METHODS

Twenty-five early abstinent cocaine-dependent individuals were administered a battery of neurocognitive tasks on entry into treatment (baseline) and again following 3 weeks of either placebo or guanfacine treatment (up to 3 mg). Tasks included: Stop Signal, Stroop, 3-Dimentional Intra-dimensional/Extra-dimensional (IDED) task, Spatial Working Memory (SWM), Paired Associates Learning (PAL), Verbal Fluency and the Rey Auditory Verbal Learning Test (RAVLT).

RESULTS

Compared with placebo, the guanfacine group demonstrated attenuated anxiety and negative affect as well as improved performance on selective executive tests. This included fewer directional errors on the stop signal task, fewer errors on the extra-dimensional shift component of the IDED task and better attentional switching during verbal fluency. Guanfacine did not improve strategic working memory or peripheral memory.

CONCLUSION

Guanfacine improves selective cognitive processes which may underlie salient treatment-related regulatory behaviors. Alpha2 agonists may therefore represent important agents for cocaine dependence.

Abnormal white matter integrity and impairment of cognitive abilities in adolescent inhalant abusers

Inhalant abuse represents a major health problem especially among adolescents and young adults. However, less is known about white matter (WM) microstructure in adolescent inhalant abusers. In the present study, we used diffusion tensor imaging (DTI) to study WM changes in adolescent inhalant abusers compared with healthy controls. We also tested whether there was any relationship between WM integrity and neuropsychological measures in adolescent inhalant abusers. The study included 19 adolescent inhalant abusers and 19 healthy control subjects. Whole brain analysis of WM microstructure was performed using tract-based spatial statistics (TBSS) to detect abnormal WM regions between groups. Wisconsin card sorting test (WCST) and Stroop test were used to measure neuropsychological performance. We found that adolescent inhalant abuser group had significantly higher axial diffusivity (AD) values in left parietal, occipital and temporal WM than in healthy control group. Inhalant abuser and control groups did not differ significantly on fractional anisotropy (FA) and radial diffusivity (RD) values. Adolescent inhalant abusers showed worse performance when compared with control group in WCST and Stroop test. There was no significant correlation of AD values in significant clusters with neuropsychological test performances within the two groups. We only found discrete impairments in neuropsychological test performance and WM integrity in adolescent inhalant abusers compared with healthy control subjects and we were not able to demonstrate a direct correlation between WM alterations and neurocognitive performance. Future work is required to longitudinally evaluate brain abnormalities through methods assessing brain structure, function and connectivity.

Altered cerebellar and prefrontal cortex function in rhesus monkeys that previously self-administered cocaine

RATIONALE

Differences in brain function in cocaine users can occur even when frank deficits are not apparent, indicating neuroadaptive consequences of use. Using monkeys to investigate altered metabolic activity following chronic cocaine self-administration allows an assessment of altered function due to cocaine use, without confounding pre-existing differences or polysubstance use often present in clinical studies.

OBJECTIVES

To evaluate alterations in metabolic function during a working memory task in the prefrontal cortex and the cerebellum following 1 year of chronic cocaine self-administration followed by a 20 month drug-free period.

METHODS

Fluorodeoxyglucose ((18)F) PET imaging was used to evaluate changes in relative regional metabolic activity associated with a delayed match to sample working memory task. Chronic cocaine animals were compared to a control group, and region of interest analyses focused on the dorsolateral prefrontal cortex (DLPFC) and cerebellum.

RESULTS

Despite no differences in task performance, in the cocaine group, the cerebellum showed greater metabolic activity during the working memory task (relative to the control task) compared to the control group. There was also a trend toward a significant difference between the groups in DLPFC activity (p = 0.054), with the cocaine group exhibiting lower DLPFC metabolic activity during the delay task (relative to the control task) than the control group.

CONCLUSION

The results support clinical indications of increased cerebellar activity associated with chronic cocaine exposure. Consistent with evidence of functional interactions between cerebellum and prefrontal cortex, these changes may serve to compensate for potential impairments in functionality of DLPFC.

Decision-making impairment predicts 3-month hair-indexed cocaine relapse

RATIONALE

One of the key outstanding challenges in cocaine dependence research is determining who is at risk of relapsing during treatment.

OBJECTIVES

We examined whether cognitive decision-making profiles predict objectively (hair) indexed cocaine relapse at 3-month follow-up.

METHODS

Thirty-three cocaine-dependent patients commencing outpatient treatment in a public clinic performed baseline decision-making assessments with the original and variant versions of the Iowa Gambling Task, and provided a 3-cm hair sample 3 months afterwards. Based on Iowa Gambling Tasks' performance cut-offs, 5 patients had intact decision-making skills, 17 patients showed impaired sensitivity to reward or punishment (impairment in one of the tasks), and 9 patients showed insensitivity to future consequences (impairment in both tasks). Based on a 0.3 ng/mg cocaine cut-off, 23 patients were classified as relapsers and 10 as non-relapsers at the 3-month follow-up.

RESULTS

Eighty percent of patients with intact decision-making were abstinent at follow-up, whereas 90% of patients with insensitivity to future consequences had relapsed. The two subgroups (relapsers and non-relapsers) showed no significant differences on drug use, comorbidities, or psychosocial function, and significantly differed on verbal but not performance IQ. A regression model including decision-making scores and verbal IQ predicted abstinence status with high sensitivity (95%) and moderately high specificity (81%).

CONCLUSION

These preliminary findings demonstrate that decision-making profiles are associated with cocaine relapse. Moreover, combined decision-making and IQ assessments provide optimal predictive values over stimulant relapse, yielding significant opportunities for clinical translation.

PET studies in nonhuman primate models of cocaine abuse: translational research related to vulnerability and neuroadaptations

The current review highlights the utility of positron emission tomography (PET) imaging to study the neurobiological substrates underlying vulnerability to cocaine addiction and subsequent adaptations following chronic cocaine self-administration in nonhuman primate models of cocaine abuse. Environmental (e.g., social rank) and sex-specific influences on dopaminergic function and sensitivity to the reinforcing effects of cocaine are discussed. Cocaine-related cognitive deficits have been hypothesized to contribute to high rates of relapse and are described in nonhuman primate models. Lastly, the long-term consequences of cocaine on neurobiology are discussed. PET imaging and longitudinal, within-subject behavioral studies in nonhuman primates have provided a strong framework for designing pharmacological and behavioral treatment strategies to aid drug-dependent treatment seekers. Non-invasive PET imaging will allow for individualized treatment strategies. Recent advances in radiochemistry of novel PET ligands and other imaging modalities can further advance our understanding of stimulant use on the brain. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.

Optimal neurocognitive, personality and behavioral measures for assessing impulsivity in cocaine dependence

BACKGROUND

Impulsivity may underlie the poor treatment retention and high relapse rates observed in cocaine-dependent persons. However, observed differences in measures of impulsivity between cocaine-dependent and healthy control participants often do not reach clinical significance, suggesting that the clinical relevance of these differences may be limited.

OBJECTIVES

To examine which measures of impulsivity (i.e. self-report impulsivity, self-report personality, neurocognitive testing) best distinguish cocaine-dependent and healthy control participants (i.e. showing differences at least 1.5 standard deviations [SD] from controls). Optimal measures were considered to demonstrate sufficient classification accuracy.

METHODS

Sixty-five recently abstinent cocaine-dependent and 25 healthy control participants were assessed using select neurocognitive tests and self-report questionnaires including the NEO Personality Inventory-Revised (NEO-PI-R), Temperament and Character Inventory (TCI), Barratt Impulsiveness Scale (BIS-11a), and the Frontal Systems Behavior Scale (FrSBe).

RESULTS

When corrected for years of education and gender, neurocognitive measures did not demonstrate clinically significant differences between cocaine-dependent and control participants. The personality measures TCI Purposefulness and Congruent Second Nature and NEO-PI-R Impulsiveness, and the self-rating measures FrSBe Disinhibition and BIS-11 Motor Impulsivity and Total successfully identified clinically meaningful elevations in impulsivity within cocaine-dependent participants (>1.5 SDs from controls). Furthermore, these measures achieved 84-93% accuracy in discriminating cocaine-dependent from control participants.

CONCLUSION

Clinically significant neurocognitive impairment in cocaine-dependent participants was not observed in this sample. As the BIS-11 or FrSBe are brief to administer, accurate, and have been shown to predict treatment retention and relapse, these measures appear to be optimal, relative to the personality measures, for examining trait impulsivity in cocaine dependence.

Neuropsychological performance of methadone-maintained opiate users

Methadone maintenance treatment (MMT) has been used to treat opiate dependence since the mid-1960s. Previous studies have investigated the effects of methadone on cognitive function however the findings have been inconsistent. Some report a complete absence of deficits while others report different types of cognitive impairment. Our research aimed to investigate the effects of MMT on cognitive function by comparing the performance of patients currently enrolled in MMT (n=32) with opiate-dependent subjects (n=17) and healthy control subjects (n=25) on a computerised neuropsychological test battery. Both the patients undertaking MMT and the opiate users showed less efficient interaction between visual searching and manually connecting digits and letters during the Switching of Attention Task than the healthy control subjects (F(2,64)=3.25, p=0.05), which indicates deficits in information processing. Nevertheless, the performance of the MMT group was similar to that of healthy control subjects in all other tasks, in contrast to the group of opiate users who performed poorly when compared to healthy control subjects during tests of attention (mean difference (MD)=2.8, 95% confidence interval (CI) (0.9-4.7), p=0.001) and executive function (MD=5.9, 95% CI (1.3-10.5), p=0.007). These findings suggest that cognitive function in patients undertaking MMT is improved compared to those dependent on illicit opiates.

Striatal-insula circuits in cocaine addiction: implications for impulsivity and relapse risk

BACKGROUND

Dysregulated striatal functioning coupled with executive control deficits arising from abnormal frontal cortical function are considered key mechanisms in the development and maintenance of cocaine addiction. The same features are thought to underlie high trait impulsivity observed in cocaine-addicted populations.

OBJECTIVES

Employing resting state functional connectivity, the current study sought to identify cortico-striatal circuit alterations in cocaine addiction and examine the degree to which circuit connectivity contributes to relapse risk and impulsivity among cocaine-addicted individuals.

METHODS

Whole-brain resting-state functional magnetic resonance imaging connectivity was assessed in 45 cocaine-addicted individuals relative to 22 healthy controls using seed volumes in the left and right caudate, putamen and nucleus accumbens. Cocaine-addicted individuals completed scans in the final week of a 2-4 weeks residential treatment episode. Relapse by day 30 post-discharge served to separate cocaine-addicted individuals into relapse and non-relapse groups. All participants completed the Barratt Impulsivity Scale (BIS-11a).

RESULTS

Cocaine-addicted individuals exhibited reduced positive connectivity between the bilateral putamen and posterior insula and right postcentral gyrus. Group differences were primarily driven by reduced connectivity in relapse individuals relative to controls. No relapse versus non-relapse differences emerged. Impulsivity (BIS-11a) was higher in cocaine-addicted participants, an effect that was partially mediated by reduced putamen-posterior insula connectivity in this group.

CONCLUSION

Cocaine addiction, relapse risk and impulsivity were associated with reduced connectivity in putamen-posterior insula/postcentral gyrus circuits implicated in temporal discounting and habitual responding. Findings provide new insight into the neurobiological mechanisms underlying impulsivity and relapse in cocaine addiction.

Neuropsychological Assessment Battery-Screening Module (S-NAB): performance in treatment-seeking cocaine users

Abstract Background: Cocaine use is associated with cognitive impairments, which can have a negative effect on treatment retention and drug use. Thus, there is an increasing demand for a screening cognitive battery can be used by clinicians to detect such impairments in cocaine patients so that treatment can be adapted to patients' specific cognitive strengths and deficits. The Neuropsychological Assessment Battery-Screening Module (S-NAB) test for adults takes approximately 35-45 min to administer, and assesses attention, language, memory (verbal and visual), visual spatial reasoning, and executive functioning.

OBJECTIVE

The purpose of this descriptive study was to present S-NAB score results for a sample of treatment seeking adult cocaine users to determine its potential utility for detecting cognitive impairments in this population.

METHODS

In the present sample, 145 adult cocaine users participated in screening to enroll in an intervention to decrease cocaine use (59% male; 73.1% African American); screening included the S-NAB and self-report questionnaires.

RESULTS

A substantial proportion of the sample (44%) met criteria for impairment, i.e. composite scores of one or more standard deviations below the mean. Furthermore, memory scores were significantly lower than language and spatial scores (p < 0.007).

CONCLUSIONS

The impairments detected by the S-NAB were generally consistent with those previously observed in samples of cocaine users completing other batteries, as well in other substance abusing samples completing the S-NAB. This suggests that the S-NAB can be considered an additional appropriate battery, as an alternative to other existing batteries, for assessment of the cognitive functioning of adult cocaine users.

Preliminary findings of the effects of rivastigmine, an acetylcholinesterase inhibitor, on working memory in cocaine-dependent volunteers

Long-term cocaine use is a risk factor for the onset of neurocognitive impairment. This study sought to determine whether the cholinesterase inhibitor rivastigmine could improve neurocognitive performance in cocaine-dependent individuals. Cocaine-dependent individuals who were not seeking treatment at the time of enrollment in the study were randomly assigned to receive placebo (n=16), rivastigmine 3mg (n=13), or rivastigmine 6mg (n=12). The baseline neurocognitive assessment, which included measures of attention/information processing (as measured by the Continuous Performance Task-II (CPT-II)), verbal learning/episodic memory (as measured by the Hopkins Verbal Learning Test-Revised (HVLT-R)), and working memory (as measured by the Dual N-Back Task), was conducted prior to the administration of study medication (Day 0). The follow-up assessment was conducted on Day 8 after the participants had received rivastigmine or placebo for 7days (Day 2-8). Rivastigmine administration significantly improved performance on one measure of working memory span (mean n-back span). This study provides additional data showing that cocaine-associated neurocognitive impairment, specifically working memory deficits, can be remediated, at least to some degree.

Mediated and moderated effects of neurocognitive impairment on outcomes of treatment for substance dependence and major depression

OBJECTIVE

Neurocognitive impairment has not consistently predicted substance use treatment outcomes but has been linked to proximal mediators of outcome. These indirect effects have not been examined in adults with substance dependence and co-occurring psychiatric disorders. We examined mediators and moderators of the effects of neurocognitive impairment on substance use among adults in treatment for alcohol or drug dependence and major depression (MDD).

METHOD

Participants were veterans (N = 197, mean age = 49.3 years, 90% male, 75% Caucasian) in a trial of 2 group interventions for alcohol/drug dependence and MDD. Measures examined here included intake neurocognitive assessments and percent days drinking (PDD), percent days using drugs (PDDRG), self-efficacy, 12-step affiliation, and depressive symptoms measured every 3 months from intake to the 18-month follow-up.

RESULTS

Greater intake neurocognitive impairment predicted lower self-efficacy, lower 12-step affiliation, and greater depression severity, and these time-varying variables mediated the effects of impairment on future PDD and PDDRG. The prospective effects of 12-step affiliation on future PDD were greater for those with greater neurocognitive impairment. Impairment also interacted with depression to moderate the effects of 12-step affiliation and self-efficacy on PDD. Adults with greater impairment and currently severe depression had the strongest associations between 12-step affiliation/self-efficacy and future drinking.

CONCLUSIONS

Greater neurocognitive impairment may lead to poorer outcomes from group therapy for alcohol/drug dependence and MDD due to compromised change in therapeutic processes. Distal factors such as neurocognitive impairment can interact with dynamic risk factors to modulate the association between therapeutic processes and future drinking outcomes.

Neural correlates of reward-based spatial learning in persons with cocaine dependence

Dysfunctional learning systems are thought to be central to the pathogenesis of and impair recovery from addictions. The functioning of the brain circuits for episodic memory or learning that support goal-directed behavior has not been studied previously in persons with cocaine dependence (CD). Thirteen abstinent CD and 13 healthy participants underwent MRI scanning while performing a task that requires the use of spatial cues to navigate a virtual-reality environment and find monetary rewards, allowing the functional assessment of the brain systems for spatial learning, a form of episodic memory. Whereas both groups performed similarly on the reward-based spatial learning task, we identified disturbances in brain regions involved in learning and reward in CD participants. In particular, CD was associated with impaired functioning of medial temporal lobe (MTL), a brain region that is crucial for spatial learning (and episodic memory) with concomitant recruitment of striatum (which normally participates in stimulus-response, or habit, learning), and prefrontal cortex. CD was also associated with enhanced sensitivity of the ventral striatum to unexpected rewards but not to expected rewards earned during spatial learning. We provide evidence that spatial learning in CD is characterized by disturbances in functioning of an MTL-based system for episodic memory and a striatum-based system for stimulus-response learning and reward. We have found additional abnormalities in distributed cortical regions. Consistent with findings from animal studies, we provide the first evidence in humans describing the disruptive effects of cocaine on the coordinated functioning of multiple neural systems for learning and memory.

Environmental modulation of drug taking: Nonhuman primate models of cocaine abuse and PET neuroimaging

The current review highlights the importance of environmental variables on cocaine self-administration in nonhuman primate models of drug abuse. In addition to describing the behavioral consequences, potential mechanisms of action are discussed, based on imaging results using the non-invasive and translational technique of positron emission tomography (PET). In this review, the role of three environmental variables - both positive and negative - are described: alternative non-drug reinforcers; social rank (as an independent variable) and punishment of cocaine self-administration. These environmental stimuli can profoundly influence brain function and drug self-administration. We focus on environmental manipulations involving non-drug alternatives (e.g., food reinforcement) using choice paradigms. Manipulations such as response cost and social variables (e.g., social rank, social stress) also influence the behavioral effects of drugs. Importantly, these manipulations are amenable to brain imaging studies. Taken together, these studies emphasize the profound impact environmental variables can have on drug taking, which should provide important information related to individual-subject variability in treatment responsiveness, and the imaging work may highlight pharmacological targets for medications related to treating drug abuse. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Methamphetamine-induced increases in putamen gray matter associate with inhibitory control

RATIONALE

Problematic drug use is associated with difficulty in exerting self-control over behaviors, and this difficulty may be a consequence of atypical morphometric characteristics that are exhibited by drug-experienced individuals. The extent to which these structural abnormalities result from drug use or reflect neurobiological risk factors that predate drug use, however, is unknown.

OBJECTIVES

The purpose of this study is to determine how methamphetamine affects corticostriatal structure and how drug-induced changes relate to alterations in inhibitory control.

METHODS

Structural magnetic resonance images and positron emission tomography (PET) scans, assessing dopamine D₂-like receptor and transporter availability, were acquired in monkeys trained to acquire, retain, and reverse three-choice visual discrimination problems before and after exposure to an escalating dose regimen of methamphetamine (or saline, as a control). Voxel-based morphometry was used to compare changes in corticostriatal gray matter between methamphetamine- and saline-exposed monkeys. The change in gray matter before and after the dosing regimen was compared to the change in the behavioral performance and in dopaminergic markers measured with PET.

RESULTS

Methamphetamine exposure, compared to saline, increased gray matter within the right putamen. These changes were positively correlated with changes in performance of methamphetamine-exposed monkeys in the reversal phase, and were negatively correlated with alterations in D₂-like receptor and DAT availability.

CONCLUSIONS

The results provide the first evidence that exposure to a methamphetamine dosing regimen that resembles human use alters the structural integrity of the striatum and that gray-matter abnormalities detected in human methamphetamine users are due, at least in part, to the pharmacological effects of drug experience.

Cognitive enhancement as a treatment for drug addictions

Drug addiction continues to be an important public health problem, with an estimated 22.6 million current illicit drug users in the United States alone. For many addictions, including cocaine, methamphetamine, and marijuana addiction, there are no approved pharmacological treatments. Behavioral treatments are effective but effects vary widely across individuals. Treatments that are effective across multiple addictions are greatly needed, and accumulating evidence suggests that one such approach may be pharmacological or behavioral interventions that enhance executive inhibitory control in addicts. Current evidence indicates that most forms of chronic drug use may be associated with significant cognitive impairments, especially in attention, working memory, and response inhibition functions. In some studies, these impairments predict poor treatment retention and outcome. A number of cognitive enhancing agents, including galantamine, modafinil, atomoxetine, methylphenidate, and guanfacine, have shown promising findings in human studies. Specific behavioral interventions, including cognitive remediation, also show promise. However, whether improvement of selective cognitive functions reduces drug use behavior remains to be determined. Cognitive enhancement to improve treatment outcomes is a novel strategy worthy of future research, as are related questions such as whether these approaches may be broadly beneficial to most addicts or best reserved for substance users with specific demonstrated cognitive impairments. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Disadvantageous Decision-Making as a Predictor of Drop-Out among Cocaine-Dependent Individuals in Long-Term Residential Treatment

BACKGROUND

The treatment of cocaine-dependent individuals (CDI) is substantially challenged by high drop-out rates, raising questions regarding contributing factors. Recently, a number of studies have highlighted the potential of greater focus on the clinical significance of neurocognitive impairments in treatment-seeking cocaine users. In the present study, we hypothesized that disadvantageous decision-making would be one such factor placing CDI at greater risk for treatment drop-out.

METHODS

In order to explore this hypothesis, the present study contrasted baseline performance (at treatment onset) on two validated tasks of decision-making, the Iowa Gambling Task (IGT) and the Cambridge Gamble Task (CGT) in CDI who completed treatment in a residential Therapeutic Community (TC) (N = 66) and those who dropped out of TC prematurely (N = 84).

RESULTS

Compared to treatment completers, CDI who dropped out of TC prematurely did not establish a consistent and advantageous response pattern as the IGT progressed and exhibited a poorer ability to choose the most likely outcome on the CGT. There were no group differences in betting behavior.

CONCLUSION

Our findings suggest that neurocognitive rehabilitation of disadvantageous decision-making may have clinical benefits in CDI admitted to long-term residential treatment programs.

Effects of chronic cocaine self-administration on cognition and cerebral glucose utilization in Rhesus monkeys

BACKGROUND

Chronic cocaine use is associated with neurobiological and cognitive deficits that persist into abstinence, hindering success of behavioral treatment strategies and perhaps increasing likelihood of relapse. The effects of current cocaine use and abstinence on neurobiology and cognition are not well characterized.

METHODS

Adult male rhesus monkeys with an extensive cocaine self-administration history (∼ 5 years) and age-matched control animals (n = 4/group) performed cognitive tasks in morning sessions and self-administered cocaine or food in afternoon sessions. Positron emission tomography and [(18)F]-fluorodeoxyglucose were employed to assess cerebral metabolic rates of glucose utilization during cognitive testing.

RESULTS

Cocaine-experienced monkeys required significantly more trials and committed more errors on reversal learning and multidimensional discriminations, compared with control animals. Cocaine-naive, but not cocaine-experienced, monkeys showed greater metabolic rates of glucose utilization during a multidimensional discrimination task in the caudate nucleus, hippocampus, anterior and posterior cingulate, and regions associated with attention, error detection, memory, and reward. Using a delayed match-to-sample task, there were no differences in baseline working memory performance between groups. High-dose cocaine self-administration disrupted delayed match-to-sample performance but tolerance developed. Acute abstinence from cocaine did not affect performance, but by day 30 of abstinence, accuracy increased significantly, while performance of cocaine-naive monkeys was unchanged.

CONCLUSIONS

These data document direct effects of cocaine self-administration on cognition and neurobiological sequelae underlying cognitive deficits. Improvements in working memory can occur in abstinence, albeit across an extended period critical for treatment seekers, suggesting pharmacotherapies designed to enhance cognition may improve success of current behavioral modification strategies.

Caudolateral orbitofrontal regional cerebral blood flow is decreased in abstinent cocaine-addicted subjects in two separate cohorts

The orbitofrontal cortex (OFC) is crucial for the inhibition of extraneous stimuli, evaluation of aversive information and emotional regulation-all behaviors impaired in cocaine addiction. Previous studies suggest that cocaine-addicted subjects have decreased basal activity in the OFC. In this study, we examined regional cerebral blood flow (rCBF) during a saline infusion in two independent populations of abstinent cocaine- (and mostly nicotine-) addicted (n=33 and 26) and healthy control (n=35 and 20) men and women. Isolated rCBF decreases (P<0.001) were observed in the left caudolateral OFC, as well as left superior temporal cortex, in cocaine-addicted subjects relative to controls in both cohorts and bilaterally in the combined cohort. An anatomically defined region of the caudolateral OFC showed similar findings and were evident in both male and female addicted subjects. The reliability of these findings across two cohorts reveals a functional disruption in the lateral OFC, a brain region implicated in the evaluation of behavior-terminating stimuli. This may contribute to an addicted individual's persistent drug use despite negative consequences.

Comparison of impulsivity and working memory in cocaine addiction and pathological gambling: Implications for cocaine-induced neurotoxicity

BACKGROUND

The aim of this study was to compare the cognitive performance of cocaine dependent individuals (CDI) with that of pathological gamblers (PG). Cocaine dependence and pathological gambling share neurobiological vulnerabilities related to addiction, but PG are relatively free of the toxic consequences, such that any additional deficits observed in CDI may be interpreted as pertaining to specific drug effects.

METHODS

We used a case-control observational design contrasting multiple measures of impulsivity (UPPS-P trait impulsivity, delay discounting) and executive measures of response inhibition (Stroop) and working memory performance (N-back) between groups of CDI (n=29), PG (n=23), and healthy controls (n=20). We conducted one-way ANOVAs, followed by planned pairwise tests and calculations of Cohen's d to estimate significant differences between the groups.

RESULTS

CDI, as compared to PG, had elevated scores on UPPS-P Negative Urgency and poorer performance on working memory (2-back). PG had steeper delay-discounting rates. Both groups had elevated Positive Urgency and poorer Stroop inhibition compared to controls. Peak amount of cocaine use was negatively correlated with working memory and response inhibition performance.

CONCLUSION

We found cocaine-related specific elevations in Negative Urgency and working memory deficits, putatively identified as cocaine neurotoxicity effects. Other aspects of impulsivity (Positive Urgency, Stroop inhibition) were increased across CDI and PG groups and may reflect vulnerability factors for addiction.

A Web-Based Behavior Therapy Program Influences the Association Between Cognitive Functioning and Retention and Abstinence in Clients Receiving Methadone Maintenance Treatment

OBJECTIVE

Deficits in cognitive functioning have been well-documented in persons with substance use disorders. In addition, some evidence suggests that poorer cognitive functioning predicts poorer engagement in substance abuse treatment and worse treatment outcomes.

TRIAL DESIGN

Non-blind, randomized clinical trial with parallel design.

METHODS

Clients were recruited from a local methadone maintenance clinic within the first 30 days of treatment. All participants completed a comprehensive, computerized neuropsychological assessment (MicroCog) at the time they entered the clinical trial. Participants were randomized to receive 12 months of either standard methadone maintenance treatment, or methadone maintenance treatment with an integrated web-based intervention as part of treatment. The aims of the current study were to (1) characterize the cognitive functioning of clients entering methadone maintenance treatment; (2) evaluate the impact of cognitive functioning on the primary outcomes of treatment retention and opioid abstinence; and (3) determine whether cognitive functioning had a differential impact on these outcomes across treatment conditions. Randomization was non-blind and participants were stratified on past month cocaine use, prior history of methadone, LAAM or buprenorphine treatment, and counselor.

RESULTS

Eighty participants were randomized to each condition (total n=160). Mean scores on MicroCog scales fell in the average and low average ranges and there were no differences in scores between treatment groups. Lower scores on General Cognitive Proficiency predicted longer study retention (χ²=5.03, p < .05), though this effect was quite small. Generalized linear modeling showed that scores on all MicroCog scales except for Spatial Processing significantly predicted opioid abstinence (defined as percent of total weeks and percent of tested weeks with continuous abstinence), with lower scores predicting smaller percentages of continuous weeks of abstinence. This pattern was not evident in regression analyses in which abstinence was defined as number of total weeks of abstinence. An interaction effect was observed, whereby lower cognitive scores predicted lower levels of abstinence for participants in standard methadone maintenance treatment, but not for those who received the web-based intervention as part of methadone maintenance treatment.

CONCLUSIONS

Technology-based interventions may hold promise for minimizing the impact of poorer cognitive functioning on treatment outcomes.

Effects of nicotinic acetylcholine receptor agonists on cognition in rhesus monkeys with a chronic cocaine self-administration history

Cocaine use is associated with impaired cognitive function, which may negatively impact treatment outcomes. One pharmacological strategy to improve cognition involves nicotinic acetylcholine receptor (nAChR) stimulation. However, the effects of chronic cocaine exposure on nAChR distribution and function have not been characterized. Thus, one goal of this study was to examine nAChR availability in rhesus monkeys with an extensive cocaine self-administration history (n = 4; ~6 years, mean intake, 1463 mg/kg) compared to age-matched cocaine-naive control monkeys (n = 5). Using [¹¹C]-nicotine and positron emission tomography (PET) imaging, cocaine-experienced monkeys showed significantly higher receptor availability in the hippocampus compared to cocaine-naive monkeys. A second goal was to examine the effects of nAChR agonists on multiple domains of cognitive performance in these same monkeys. For these studies, working memory was assessed using a delayed match-to-sample (DMS) task, associative learning and behavioral flexibility using stimulus discrimination and reversal learning tasks. When administered acutely, the nonselective high-efficacy agonist nicotine, the low-efficacy α4β2* subtype-selective agonist varenicline and the high-efficacy α7 subtype-selective agonist, PNU-282987 significantly improved DMS performance in both cocaine-naive and cocaine-experienced monkeys. Individual doses of nicotine and varenicline that engendered maximum cognitive enhancing effects on working memory did not affect discrimination or reversal learning, while PNU-282987 disrupted reversal learning in the cocaine-naive monkeys. These findings indicate that a cocaine self-administration history influenced nAChR distribution and the effects of nAChR agonists on cognitive performance, including a reduced sensitivity to the disrupting effects on reversal learning. The cognitive enhancing effects of nAChR agonists may be beneficial in combination with behavioral treatments for cocaine addiction. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Modafinil, but not escitalopram, improves working memory and sustained attention in long-term, high-dose cocaine users

OBJECTIVE

The purpose of the present study was to determine the effects of modafinil, escitalopram, and modafinil + escitalopram administration on neurocognition in a sample of long-term, high-dose cocaine users.

METHOD

Sixty-one cocaine-dependent individuals were randomly assigned to receive placebo (n = 14), modafinil, 200 mg, once daily (n = 16), escitalopram, 20 mg, once daily (n = 16), or modafinil and escitalopram, once daily (n = 15), for five days on an inpatient basis. Urinanalysis was used to confirm abstinence from cocaine on the day of admission and the next five days. Baseline neurocognitive assessment, which included measures of attention/information processing, episodic memory, and working memory, was conducted immediately after the washout phase and prior to the administration of modafinil. The follow-up assessment was conducted after participants had received modafinil or placebo for five days.

RESULTS

Repeated-measures, mixed model analysis of variance showed that modafinil administration was associated with significantly improved performance on two measures of working memory span (mean n-back span, maximum n-back span) and a trend toward significant improvement on a measure of visual working memory (visual accuracy) and two measures of sustained attention, consistency of response time (Variability) and reduced impulsivity (Perseveration). Modafinil administration did not modulate performance on measures of information processing speed or episodic memory. Escitalopram did not modulate performance on measures of cognition, either alone or in combination with modafinil.

CONCLUSIONS

This study provides initial data showing that, in a sample of long-term, high-dose cocaine users, administration of psychotropic medications, such as modafinil, can improve performance on measures of working memory. Moreover, it confirms the utility of studying the interactive effects of psychotropic medications to confirm the manner in which the candidate medications independently and interactively affect neurocognition. These effects are likely relevant in the treatment of cocaine dependence, in which the remediation of impaired working memory may be associated with improved treatment outcomes. This article is part of a Special Issue entitled 'Cognitive Enhancers'.