Temporal discounting in heroin-dependent patients: no sign effect, weaker magnitude effect, and the relationship with inhibitory control

Compulsivity and Inhibitory Control Deficits in Abstinent Individuals With Heroin Addiction and Their Biological Siblings Compared With Unrelated Healthy Control Participants

BACKGROUND

Compulsivity represents the performance of persistent and repetitive acts despite negative consequences and is considered one of the critical mechanisms for drug addiction. Although compulsivity-related neurocognitive impairments have been linked to addiction, it remains unclear whether these deficits might have predated drug abuse as potential familial susceptibilities.

METHODS

A large sample of 213 adult participants were recruited, including 70 abstinent individuals addicted to heroin (HAs), 69 unaffected biological siblings of the HAs (siblings), and 74 unrelated healthy control participants. Compulsivity-related neurocognitive functions were evaluated using the intradimensional/extradimensional set-shift task and a probabilistic reversal learning task. Compulsive traits were measured by the Obsessive-Compulsive Inventory-Revised. Inhibitory control was assessed using the stop signal task and Stroop Color and Word Test. Network models for group recognition were conducted using multilayer perceptron neural networks.

RESULTS

Data indicated that both HAs and siblings performed worse than healthy control participants on compulsivity-related aspects (i.e., shifting and reversal learning functions) and inhibitory control and had higher levels of self-reported compulsive traits. Furthermore, neural models revealed that a possible 3-facet clustering of neurocognitive deficits was linked to both HAs and siblings.

CONCLUSIONS

Our findings suggest that deficits in shift reversal and inhibitory control aspects and elevated compulsive traits, shared by HAs and their unaffected siblings, may putatively represent conceivable markers associated with familial vulnerabilities implicated in the development of heroin dependence.

Influence of improved behavioral inhibition on decreased cue-induced craving in heroin use disorder: A preliminary intermittent theta burst stimulation study

BACKGROUND

Impaired behavioral inhibition is a critical factor in drug addiction and relapse. Repetitive transcranial magnetic stimulation (rTMS) reduces the craving of heroin-addicted individuals for drug-related cues. However, it is unclear whether this technique also improves impaired behavioral inhibition and how improved behavioral inhibition affects craving.

OBJECTIVE

The intermittent theta-burst stimulation (iTBS) has been recently shown to be non-inferior relative to rTMS for depression. Here, we aim to investigate the effect of iTBS on heroin-addicted individuals' behavioral inhibition and cue-induced craving and the relationship between the alteration of behavioral inhibition and craving.

METHOD

42 of 56 initially recruited individuals with the heroin-use disorder in the abstinent-course treatment were randomized to undergo active or sham iTBS to the left dorsolateral prefrontal cortex and received three daily iTBS treatments for 10 consecutive days. We measured participants' performance during a two-choice oddball task (80% standard and 20% deviant trials) and heroin-related cue-induced craving before and immediately after treatment.

RESULTS

The group that received active iTBS showed significantly improved two-choice oddball task performance after 10 days of intervention compared to both pre-intervention and the group who received sham iTBS. Similarly, a significant reduction in cue-induced craving was observed after following the intervention in the active iTBS group but not the sham iTBS group. The moderation model indicated that iTBS categories play a significant moderating role in the relationship between accuracy cost changing and altered cue-induced craving.

CONCLUSIONS

The iTBS treatment protocol positively affects behavioral inhibition in patients with heroin addiction. Improvements in behavioral inhibition can substantially reduce craving.

Smoking, hazardous drinking and individual differences in cost and gain discounting

Aims:

Past research has linked substance use to individual differences in discounting of future rewards. Since behaviours such as smoking and excessive drinking appear to involve a devaluation of future negative consequences, discounting of costs may also be relevant in the understanding of such behaviour. The primary aims were to investigate the association between cost discounting and the behaviours smoking and hazardous drinking.

Methods:

In four studies, individuals recruited from the crowdsourcing marketplace Amazon Mechanical Turk responded to measures of discounting. Results were combined by meta-analysis of the standardised mean differences (d) between self-reported smokers and non-smokers, and between participants with AUDIT scores of 10+ (hazardous drinking) and those with scores below 10.

Results:

In comparison with non-smokers, smokers’ relative valuations of future gains were lower, d = –0.32, 95% CI [–0.47, –0.18]. There was no association between smoking and cost discounting, d = –0.02, 95% CI [–0.17, 0.13]. Participants with AUDIT scores of 10+ valued future gains somewhat lower than participants with scores below 10, d = –0.17, 95% CI [–0.35, 0.01]. There was no association between hazardous drinking and cost discounting, d = –0.02, 95% CI [–0.21, 0.16]. According to Bayes Factors (BF), the data supported an association between gain discounting and smoking (BF > 100). It was insensitive in the analysis of gain discounting and hazardous drinking (BF = 0.6), but it strongly supported null-effects in both analyses of cost discounting (BFs = 0.1).

Conclusion:

The results suggest that the robust link between gain discounting and smoking status does not reflect a general devaluation of future outcomes among smokers.

Cigarette-specific disgust aroused by smoking warning images strengthens smokers' inhibitory control under smoking-related background in Go/NoGo task

RATIONALE

Reduced inhibitory control is more pronounced during substance-related cue exposure among addicts. However, it is inconclusive whether smokers' inhibitory control would be impaired by smoking-related background. Furthermore, few studies explored whether the cigarette-specific disgust aroused by smoking warning images would alleviate the negative effect of smoking-related cues on smokers' inhibitory control.

OBJECTIVE

Experiment 1 investigated the effect of smoking-related background on inhibitory control in cigarette smokers with a modified Go/NoGo task and experiment 2 explored whether cigarette-specific disgust aroused by smoking warning images would alleviate the negative effect of smoking-related background on smokers' inhibitory control.

METHOD

Sixty-two male participants (32 smokers and 30 non-smokers) were recruited in experiment 1 and 51 male smokers were recruited in experiment 2.

RESULTS

Experiment 1 found that compared to neutral background, smokers made more commission errors (i.e., executing a response to a no-go target) under smoking-related background, indicating that smoking-related background has a negative effect on smokers' inhibitory control. Experiment 2 found that after experiencing cigarette-specific disgust, smokers made fewer commission errors at post-mood induction than pre-mood induction, indicating that cigarette-specific disgust aroused by smoking warning images alleviates the negative effect of smoking-related background on smokers' inhibitory control.

CONCLUSIONS

These results suggest that the negative effect of smoking-related cues on smokers' inhibitory control would be alleviated by cigarette-specific disgust aroused by smoking warning images, which emphasizes the important role of cigarette-specific disgust in strengthening smokers' inhibitory control towards smoking-related cues.

Individual differences in social distancing and mask-wearing in the pandemic of COVID-19: The role of need for cognition, self-control and risk attitude

In the United States, while the number of COVID-19 cases continue to increase, the practice of social distancing and mask-wearing have been controversial and even politicized. The present study examined the role of psychological traits in social distancing compliance and mask-wearing behavior and attitude. A sample of 233 U.S. adult residents were recruited from Amazon Mechanical Turk. Participants completed scales of social distancing compliance, mask-wearing behavior and attitude, need for cognition, self-control, risk attitude, and political ideology. Epidemiological information (seven-day positive rate and the number of cases per 100,000) was obtained based on the state participants resided in. As a result, epidemiological information did not correlate with social distancing compliance mask-wearing. Political ideology, on the other hand, was a significant factor, with a more liberal tendency being associated with greater engagement in social distancing compliance and mask-wearing behavior an attitude. Importantly, those who were more risk averse, or had a higher level of self-control or need for cognition practiced more social distancing and mask-wearing, after controlling for demographics, epidemiological information, and political ideology. Furthermore, for mask-wearing behavior, political ideology interacted with both need for cognition and self-control. Collectively, the study revealed the psychological roots of individual differences in social distancing and mask-wearing compliance.

Reduced response inhibition after exposure to drug-related cues in male heroin abstainers

RATIONALE

Deficits in response inhibition associated with heroin use could last several months after abstinence in heroin users, and their response inhibition can also be interfered with task-irrelevant drug-related cues. However, it is unclear whether exposure to drug-related cues affects subsequent response inhibition in heroin users following abstinence.

OBJECTIVES

The present study aimed to investigate how drug-related cues with different durations between stimulus presentations, referred to as stimulus onset asynchronies (SOAs), affect subsequent response inhibition in heroin abstainers (HAs) with different length of abstinence.

METHODS

Sixty-seven male HAs performed a modified Go/NoGo task in which a motor response to frequent Go targets and no response to rare NoGo targets were required and a Go or NoGo target was displayed after either a heroin-related or a neutral picture presented for the 200 ms and 600 ms SOAs.

RESULTS

The HAs responded significantly faster to Go targets following the neutral pictures for the 600 ms SOA compared to other conditions. They also made more commission errors following heroin-related pictures compared to neutral pictures regardless of the SOAs. The shorter-term HAs made more commission errors compared to the longer-term HAs following the 200 ms SOA, and it was only a trend when the SOA was 600 ms. Additionally, negative correlations between the duration of current abstinence and commission errors were observed following cues with the 200 ms SOA.

CONCLUSIONS

Impaired response inhibition in HAs can be improved through protracted drug abstinence. However, that effect can be reduced by exposure to drug-related cues, which may increase the risk of relapse.

Unpacking decision difficulty: Testing action dynamics in Intertemporal, gamble, and consumer choices

The study examined the two-factor structure of decision difficulty proposed by Cheng and González-Vallejo (2017) in new domains, and the role of numeracy in relation to these factors. Using the measurement methodology of 'mouse' (cursor) movements, participants' temporal and spatial measures were recorded when making decisions in the domains of intertemporal, gamble, and consumer choices. Task manipulations designed to affect difficulty included the sign of the payoffs (gains vs. losses), the similarity of the attribute values being compared, and attribute importance. A psychometric analysis of the measures revealed three orthogonal components, two of which, conflict and wavering, described decision difficulty. The conflict component was most affected by changes in the sign of the payoffs of intertemporal and gamble choices, with greater means observed in the loss than in the gain context. By contrast, the wavering component was most affected by changes of the similarity between the options' attributes, with greater means when the options were more similar. The study also found that choosing the long-term advantageous options in an intertemporal choice task; choosing the riskier gain and safer loss in a gamble choice task; and choosing the more expensive/better-quality hotel in a consumer choice task demonstrated greater conflict and/or wavering. The study further found that numeracy, or the degree to which individuals are able to use and interpret numbers, was negatively related to the conflict component. Taken together, the study demonstrated that decision difficulty varied with contextual changes, and action-dynamic measures reflected different facets of decision difficulty.

The Role of Dopamine D1 and D3 Receptors in N-Methyl-D-Aspartate (NMDA)/GlycineB Site-Regulated Complex Cognitive Behaviors following Repeated Morphine Administration

BACKGROUND

Opiate addiction is associated with complex cognitive impairment, which contributes to the development of compulsive drug use and relapses. Dopamine and N-methyl-D-aspartate receptors play critical roles in opiate-induced cognitive deficits. However, the roles of D1 and D3 receptors in the N-methyl-D-aspartate/glycineB receptor-regulated cognitive behaviors induced by morphine remain unknown.

METHODS

The 5-choice serial reaction time task was used to investigate the cognitive profiles associated with repeated morphine administration in D1 (D1-/-)- and D3 (D3-/-)-receptor knockout mice. The expression of phosphorylated NR1, Ca2+/calmodulin-dependent protein kinase II (CaMKII), and cAMP response element-binding protein (CREB) in the brain was examined by western blotting. D1-/- and D3-/- mice were treated with the N-methyl-D-aspartate/glycineB site agonist l-aminocyclopropanecarboxylic acid and the antagonist L-701,324 to chronically disrupt N-methyl-D-aspartate receptor function and investigate their effects on morphine-induced cognitive changes.

RESULTS

Repeated morphine administration impaired attentional function and caused impulsive and compulsive behaviors. D1-/- mice exhibited hardly any premature nosepokes. D3-/- mice showed robustly increased morphine-induced impulsive behavior. The numbers of premature responses were decreased by L-701,324 administration and increased by ACPC administration; these effects were completely abolished in D1-/- mice due to their inability to perform reward-based tasks. In contrast, the inhibitory effects of L-701,324 on impulsive behavior were significantly augmented in D3-/- mice.

CONCLUSIONS

N-methyl-D-aspartate/glycineB site functions may contribute to morphine-induced cognitive deficits, especially those related to impulsive behavior. D1 and D3 receptors may have contrasting effects with respect to modulating impulsive behavior. D3 receptors have inhibitory effects on impulsive behaviors, and these effects are clearly mediated by N-methyl-D-aspartate/glycineB receptor and μ-opioid receptor interactions.

Learning and generalization from reward and punishment in opioid addiction

This study adapts a widely-used acquired equivalence paradigm to investigate how opioid-addicted individuals learn from positive and negative feedback, and how they generalize this learning. The opioid-addicted group consisted of 33 participants with a history of heroin dependency currently in a methadone maintenance program; the control group consisted of 32 healthy participants without a history of drug addiction. All participants performed a novel variant of the acquired equivalence task, where they learned to map some stimuli to correct outcomes in order to obtain reward, and to map other stimuli to correct outcomes in order to avoid punishment; some stimuli were implicitly "equivalent" in the sense of being paired with the same outcome. On the initial training phase, both groups performed similarly on learning to obtain reward, but as memory load grew, the control group outperformed the addicted group on learning to avoid punishment. On a subsequent testing phase, the addicted and control groups performed similarly on retention trials involving previously-trained stimulus-outcome pairs, as well as on generalization trials to assess acquired equivalence. Since prior work with acquired equivalence tasks has associated stimulus-outcome learning with the nigrostriatal dopamine system, and generalization with the hippocampal region, the current results are consistent with basal ganglia dysfunction in the opioid-addicted patients. Further, a selective deficit in learning from punishment could contribute to processes by which addicted individuals continue to pursue drug use even at the cost of negative consequences such as loss of income and the opportunity to engage in other life activities.

Cocaine dependent individuals discount future rewards more than future losses for both cocaine and monetary outcomes

Cocaine dependence and other forms of drug dependence are associated with steeper devaluation of future outcomes (delay discounting). Although studies in this domain have typically assessed choices between monetary gains (e.g., receive less money now versus receive more money after a delay), delay discounting is also applicable to decisions involving losses (e.g., small loss now versus larger delayed loss), with gains typically discounted more than losses (the "sign effect"). It is also known that drugs are discounted more than equivalently valued money. In the context of drug dependence, however, relatively little is known about the discounting of delayed monetary and drug losses and the presence of the sign effect. In this within-subject, laboratory study, delay discounting for gains and losses was assessed for cocaine and money outcomes in cocaine-dependent individuals (n=89). Both cocaine and monetary gains were discounted at significantly greater rates than cocaine and monetary losses, respectively (i.e., the sign effect). Cocaine gains were discounted significantly more than monetary gains, but cocaine and monetary losses were discounted similarly. Results suggest that cocaine is discounted by cocaine-dependent individuals in a systematic manner similar to other rewards. Because the sign effect was shown for both cocaine and money, delayed aversive outcomes may generally have greater impact than delayed rewards in shaping present behavior in this population.

The behavioral economics of substance use disorders: reinforcement pathologies and their repair

The field of behavioral economics has made important inroads into the understanding of substance use disorders through the concept of reinforcer pathology. Reinforcer pathology refers to the joint effects of (a) the persistently high valuation of a reinforcer, broadly defined to include tangible commodities and experiences, and/or (b) the excessive preference for the immediate acquisition or consumption of a commodity despite long-term negative outcomes. From this perspective, reinforcer pathology results from the recursive interactions of endogenous person-level variables and exogenous environment-level factors. The current review describes the basic principles of behavioral economics that are central to reinforcer pathology, the processes that engender reinforcer pathology, and the approaches and procedures that can repair reinforcement pathologies. The overall goal of this review is to present a new understanding of substance use disorders as viewed by recent advances in behavioral economics.

Hyperbolic discounting: value and time processes of substance abusers and non-clinical individuals in intertemporal choice

The single parameter hyperbolic model has been frequently used to describe value discounting as a function of time and to differentiate substance abusers and non-clinical participants with the model's parameter k. However, k says little about the mechanisms underlying the observed differences. The present study evaluates several alternative models with the purpose of identifying whether group differences stem from differences in subjective valuation, and/or time perceptions. Using three two-parameter models, plus secondary data analyses of 14 studies with 471 indifference point curves, results demonstrated that adding a valuation, or a time perception function led to better model fits. However, the gain in fit due to the flexibility granted by a second parameter did not always lead to a better understanding of the data patterns and corresponding psychological processes. The k parameter consistently indexed group and context (magnitude) differences; it is thus a mixed measure of person and task level effects. This was similar for a parameter meant to index payoff devaluation. A time perception parameter, on the other hand, fluctuated with contexts in a non-predicted fashion and the interpretation of its values was inconsistent with prior findings that supported enlarged perceived delays for substance abusers compared to controls. Overall, the results provide mixed support for hyperbolic models of intertemporal choice in terms of the psychological meaning afforded by their parameters.

Cognitive control in opioid dependence and methadone maintenance treatment

BACKGROUND

Substance misuse is associated with cognitive dysfunction. We used a stop signal task to examine deficits in cognitive control in individuals with opioid dependence (OD). We examined how response inhibition and post-error slowing are compromised and whether methadone maintenance treatment (MMT), abstinence duration, and psychiatric comorbidity are related to these measures in individuals with OD.

METHODS

Two-hundred-and-sixty-four men with OD who were incarcerated at a detention center and abstinent for up to 2 months (n = 108) or at a correctional facility and abstinent for approximately 6 months (n = 156), 65 OD men under MMT at a psychiatric clinic, and 64 age and education matched healthy control (HC) participants were assessed. We computed the stop signal reaction time (SSRT) to index the capacity of response inhibition and post-error slowing (PES) to represent error-related behavioral adjustment, as in our previous work. We examined group effects with analyses of variance and covariance analyses, followed by planned comparisons. Specifically, we compared OD and HC participants to examine the effects of opioid dependence and MMT and compared OD sub-groups to examine the effects of abstinence duration and psychiatric comorbidity.

RESULTS

The SSRT was significantly prolonged in OD but not MMT individuals, as compared to HC. The extent of post-error slowing diminished in OD and MMT, as compared to HC (trend; p = 0.061), and there was no difference between the OD and MMT groups. Individuals in longer abstinence were no less impaired in these measures. Furthermore, these results remained when psychiatric comorbidities including misuse of other substances were accounted for.

CONCLUSIONS

Methadone treatment appears to be associated with relatively intact cognitive control in opioid dependent individuals. MMT may facilitate public health by augmenting cognitive control and thereby mitigating risky behaviors in heroin addicts.

Working memory and affective decision-making in addiction: a neurocognitive comparison between heroin addicts, pathological gamblers and healthy controls

BACKGROUND

Cognitive deficits are observed both in heroin dependence and in pathological gambling (PG) on various tasks. PG, as a non-substance addiction, is free of toxic consequences of drug use. Therefore a direct neurocognitive comparison of heroin addicts and pathological gamblers helps dissociate the consequences of chronic heroin use on cognitive function from the cognitive vulnerabilities that predispose addiction.

METHODS

A case-control design was used, comparing 58 abstinent heroin addicts, 58 pathological gamblers, and 60 healthy controls on working memory and affective decision-making functions. Working memory was assessed using the Self-ordered Pointing Test (SOPT). Affective decision-making was measured by the Iowa Gambling Task (IGT).

RESULTS

Heroin addicts performed significantly worse both on the IGT and on the SOPT, compared to healthy controls. Pathological gamblers performed worse on the IGT than healthy controls, but did not differ from controls on the SOPT. Years of heroin use were negatively correlated with working memory and affective decision-making performance in heroin addicts, while severity of gambling was not significantly correlated with any task performance in pathological gamblers.

CONCLUSIONS

Our findings indicate that deficits in affective decision-making shared by heroin dependence and PG putatively represent vulnerabilities to addiction and that working memory deficits detected only in heroin addicts may be identified as heroin-specific harmful effects.

The behavioral- and neuro-economic process of temporal discounting: A candidate behavioral marker of addiction

Addiction science would benefit from the identification of a behavioral marker. A behavioral marker could reflect the projected clinical course of the disorder, function as a surrogate measure of clinical outcome, and/or may be related to biological components that underlie the disorder. In this paper we review relevant literature, made possible with the early and sustained support by NIDA, to determine whether temporal discounting, a neurobehavioral process derived from behavioral economics and further explored through neuroeconomics, may function as a behavioral marker. Our review suggests that temporal discounting 1) identifies individuals who are drug-dependent, 2) identifies those at risk of developing drug dependence, 3) acts as a gauge of addiction severity, 4) correlates with all stages of addiction development, 5) changes with effective treatment, and 6) may be related to the biological and genetic processes that underlie addiction. Thus, initial evidence supports temporal discounting as a candidate behavioral marker. Additional studies will be required in several areas for a more conclusive determination. Confirmation that temporal discounting functions as a behavioral marker for addiction could lead to 1) a screen for new treatments, 2) personalization of prevention and treatment interventions, and 3) the extension of temporal discounting as a behavioral marker for other etiologically similar disorders. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.