Negative reinforcement learning is affected in substance dependence

Computational markers of risky decision-making predict for relapse to alcohol

BACKGROUND

Relapse remains the major challenge in treatment of alcohol use disorder (AUD). Aberrant decision-making has been found as important cognitive mechanism underlying relapse, but factors associated with relapse vulnerability are unclear. Here, we aim to identify potential computational markers of relapse vulnerability by investigating risky decision-making in individuals with AUD.

METHODS

Forty-six healthy controls and fifty-two individuals with AUD were recruited for this study. The risk-taking propensity of these subjects was investigated using the balloon analog risk task (BART). After completion of clinical treatment, all individuals with AUD were followed up and divided into a non-relapse AUD group and a relapse AUD group according to their drinking status.

RESULTS

The risk-taking propensity differed significantly among healthy controls, the non-relapse AUD group, and the relapse AUD group, and was negatively associated with the duration of abstinence in individuals with AUD. Logistic regression models showed that risk-taking propensity, as measured by the computational model, was a valid predictor of alcohol relapse, and higher risk-taking propensity was associated with greater risk of relapse to drink.

CONCLUSION

Our study presents new insights into risk-taking measurement and identifies computational markers that provide prospective information for relapse to drink in individuals with AUD.

Impaired Learning From Negative Feedback in Stimulant Use Disorder: Dopaminergic Modulation

BACKGROUND

Drug-induced alterations to the dopamine system in stimulant use disorder (SUD) are hypothesized to impair reinforcement learning (RL). Computational modeling enables the investigation of the latent processes of RL in SUD patients, which could elucidate the nature of their impairments.

METHODS

We investigated RL in 44 SUD patients and 41 healthy control participants using a probabilistic RL task that assesses learning from reward and punishment separately. In an independent sample, we determined the modulatory role of dopamine in RL following a single dose of the dopamine D2/3 receptor antagonist amisulpride (400 mg) and the agonist pramipexole (0.5 mg) in a randomised, double-blind, placebo-controlled, crossover design. We analyzed task performance using computational modelling and hypothesized that RL impairments in SUD patients would be differentially modulated by a dopamine D2/3 receptor antagonist and agonist.

RESULTS

Computational analyses in both samples revealed significantly reduced learning rates from punishment in SUD patients compared with healthy controls, whilst their reward learning rates were not measurably impaired. In addition, the dopaminergic receptor agents modulated RL parameters differentially in both groups. Both amisulpride and pramipexole impaired RL parameters in healthy participants, but ameliorated learning from punishment in SUD patients.

CONCLUSION

Our findings suggest that RL impairments seen in SUD patients are associated with altered dopamine function.

Value, drug addiction and the brain

Over the years, various models have been proposed to explain the psychology and biology of drug addiction, built primarily around the habit and compulsion models. Recent research indicates drug addiction may be goal-directed, motivated by excessive valuation of drugs. Drug consumption may initially occur for the sake of pleasure but may transition to a means of escaping withdrawal, stress and negative emotions. In this hypothetical paper, we propose a value-based neurobiological model for drug addiction. We posit that during dependency, the value-based decision-making system in the brain is not inactive but has instead prioritized drugs as the reward of choice. In support of this model, we consider the role of valuation in choice, its influence on pleasure and punishment, and how valuation is contrasted in impulsive and compulsive behaviours. We then discuss the neurobiology of value, beginning with the dopaminergic system and its relationship with incentive salience before moving to brain-wide networks involved in valuation, control and prospection. These value-based neurobiological components are then integrated into the cycle of addiction as we consider the development of drug dependency from a valuation perspective. We conclude with a discussion of cognitive interventions utilizing value-based decision-making, highlighting not just advances in recalibrating the valuation system to focus on non-drug rewards, but also areas for improvement in refining this approach.

Single Exposure to Cocaine Impairs Reinforcement Learning by Potentiating the Activity of Neurons in the Direct Striatal Pathway in Mice

Plasticity in the glutamatergic synapses on striatal medium spiny neurons (MSNs) is not only essential for behavioral adaptation but also extremely vulnerable to drugs of abuse. Modulation on these synapses by even a single exposure to an addictive drug may interfere with the plasticity required by behavioral learning and thus produce impairment. In the present work, we found that the negative reinforcement learning, escaping mild foot-shocks by correct nose-poking, was impaired by a single in vivo exposure to 20 mg/kg cocaine 24 h before the learning in mice. Either a single exposure to cocaine or reinforcement learning potentiates the glutamatergic synapses on MSNs expressing the striatal dopamine 1 (D1) receptor (D1-MSNs). However, 24 h after the cocaine exposure, the potentiation required for reinforcement learning was disrupted. Specific manipulation of the activity of striatal D1-MSNs in D1-cre mice demonstrated that activation of these MSNs impaired reinforcement learning in normal D1-cre mice, but inhibition of these neurons reversed the reinforcement learning impairment induced by cocaine. The results suggest that cocaine potentiates the activity of direct pathway neurons in the dorsomedial striatum and this potentiation might disrupt the potentiation produced during and required for reinforcement learning.

A Systematic Review of the Balloon Analogue Risk Task (BART) in Alcohol Research

Risk-taking propensity has been crucial to the investigation of alcohol use and consequences. One measure, the balloon analogue risk task (BART), has been used consistently over the past two decades. However, it is unclear how this measure is related to alcohol outcomes. This paper systematically reviews the literature on the BART and alcohol outcomes. First, direct associations between the BART and alcohol use are reviewed including correlations, group comparisons, the BART's prediction of alcohol outcomes and BART performance after consuming alcohol. Then, potential moderators that explain when and for whom the BART is related to alcohol outcomes are reviewed. Finally, potential mechanisms that explain how the BART and alcohol outcomes are related are reviewed. This review reveals patterns in the BART suggesting risk-taking propensity may be related to changes in alcohol use over time; however, there is little evidence to suggest BART scores increase after consuming alcohol. Yet, additional research suggests adjusted average pump scores may be too simplistic for the amount of information the BART captures and understanding individual's patterns of responses on the BART is important for investigating its relation to alcohol outcomes. Finally, this review opens up several future directions for research to understand how risk-taking propensity is related to alcohol outcomes.

Diminished cortical response to risk and loss during risky decision making in alcohol use disorder

BACKGROUND

Risky decision-making is an important facet of addiction. Individuals with alcohol dependence show abnormalities in gambling and other risk-taking tasks. In one such measure, the Balloon Analogue Risk Task (BART), participants sequentially choose to pump a virtual balloon to increase potential reward while the risk of explosion increases, or to cash-out and take earnings. In a prior study, alcohol-dependent participants differed from controls in brain activation during decision-making on the BART, but the relationship between risk/reward magnitude and brain activation was not studied, nor were participants compared to controls. Here we compared the degree to which risk and magnitude of reward influenced brain activation in alcohol-dependent participants vs. controls during decision-making on the BART.

METHODS

Thirty-two participants (16 alcohol-dependent, 16 control; 5 females/group) performed the BART during fMRI. A parametric analysis tested for a relationship between risk/reward magnitude and activation in rDLPFC and bilateral striatum regions of interest when participants chose to take risk or to cash out. An exploratory whole-brain voxel-wise analysis of mean activation during pumping, cash-out, and explosion events was also conducted.

RESULTS

Compared with controls, alcohol-dependent participants displayed less modulation of activation in the rDLPFC when taking risk. Exploratory analyses found that alcohol-dependent participants showed less activation than controls during explosions in a cluster including the insula. No differences were seen in striatal activation.

CONCLUSIONS

Insensitivity of the rDLPFC to risk and of the insula to loss may contribute to decision-making deficits in alcohol dependence.

Risky decision-making in individuals with substance use disorder: A meta-analysis and meta-regression review

BACKGROUND

This review aims to identify whether risky decision-making is increased in substance users, and the impact of substance type, polysubstance use status, abstinence period, and treatment status on risky decision-making.

METHODS

A literature search with no date restrictions was conducted to identify case-control studies or cross-sectional studies that used behavioral tasks to measure risky decision-making in substance users. A random-effects model was performed. GRADE criteria was used to assess the quality of evidence.

RESULTS

52 studies were enrolled. The result showed that the difference in risky decision-making performance between user groups and control groups was significant (SMD = - 0.590; 95%CI = - 0.849 to - 0.330; p < 0.001; I² = 93.4%; P_{heterogeneity} < 0.001). Subgroup analysis showed that users in the subgroups of alcohol (p < 0.001), tobacco (p < 0.01), cocaine (p < 0.001), opioid (p < 0.001), mixed group (p < 0.01), adult users (p < 0.001), small sample size (p < 0.001), large sample size (p < 0.01), low education (p < 0.001), high education (p < 0.001), short-abstinence period (p < 0.001), long-abstinence period (p < 0.001), without current polysubstance dependence (p < 0.001), and with treatment (p < 0.001) had increased risky decision-making when compared to the controls. On the other hand, elderly substance users with short-abstinence period showed increased risky decision-making. Moreover, current treatment status and polysubstance use may not influence the level of decision-making in substance users.

CONCLUSIONS

The results show that substance use is associated with impaired risky decision-making, indicating that interventions targeting risky decision-making in substance users should be developed for relapse prevention and rehabilitation.

Brain networks underlying vulnerability and resilience to drug addiction

Resting-state functional connectivity provides novel insight into variations in neural networks associated with addiction to stimulant drugs in individuals with and without a family history of addiction, and both with and without personal drug use. An increased risk for addiction, either because of drug use or genetic/psychosocial vulnerability, is associated with hypoconnectivity in frontostriatal networks, which may weaken goal-directed decision-making. Resilience against addiction development, by contrast, is characterized by hyperconnectivity in two corticostriatal pathways, possibly reflecting compensatory responses in networks associated with regulatory control over habitual behaviors. It is thus conceivable that defying the risk of developing stimulant drug addiction requires increased efforts to control behavior—a hypothesis that may open up new pathways for therapeutic and preventative strategies.

Regular drug use can lead to addiction, but not everyone who takes drugs makes this transition. How exactly drugs of abuse interact with individual vulnerability is not fully understood, nor is it clear how individuals defy the risks associated with drugs or addiction vulnerability. We used resting-state functional MRI (fMRI) in 162 participants to characterize risk- and resilience-related changes in corticostriatal functional circuits in individuals exposed to stimulant drugs both with and without clinically diagnosed drug addiction, siblings of addicted individuals, and control volunteers. The likelihood of developing addiction, whether due to familial vulnerability or drug use, was associated with significant hypoconnectivity in orbitofrontal and ventromedial prefrontal cortical-striatal circuits—pathways critically implicated in goal-directed decision-making. By contrast, resilience against a diagnosis of substance use disorder was associated with hyperconnectivity in two networks involving 1) the lateral prefrontal cortex and medial caudate nucleus and 2) the supplementary motor area, superior medial frontal cortex, and putamen—brain circuits respectively implicated in top-down inhibitory control and the regulation of habits. These findings point toward a predisposing vulnerability in the causation of addiction, related to impaired goal-directed actions, as well as countervailing resilience systems implicated in behavioral regulation, and may inform novel strategies for therapeutic and preventative interventions.

Monoaminergic modulation of decision-making under risk of punishment in a rat model

The ability to decide advantageously among options that vary in both their risks and rewards is critical for survival and well-being. Previous work shows that some forms of risky decision-making are robustly modulated by monoamine signaling, but it is less clear how monoamine signaling modulates decision-making under risk of explicit punishment. The goal of these experiments was to determine how this form of decision-making is modulated by dopamine, serotonin, and norepinephrine signaling, using a task in which rats choose between a small, 'safe' food reward and a large food reward associated with variable risks of punishment. Preference for the large, risky reward (risk-taking) was reduced by administration of a D2/3 dopamine receptor agonist (bromocriptine) and a selective D2 agonist (sumanirole). The selective D3 agonist PD128907 appeared to attenuate reward discrimination abilities but did not affect risk-taking per se. In contrast, drugs targeting serotonergic and noradrenergic signaling had few if any effects on choice behavior. These data suggest that in contrast to other forms of risky decision-making, decision-making under risk of punishment is selectively modulated by dopamine signaling, predominantly through D2 receptors.

Applying Behavioural Incentives to Increase Adherence to Maintenance Treatment

A significant portion of the various communities, especially developing countries, is involved in drug abuse and receive formal drug treatments. Although the benefits of available therapeutics such as methadone maintenance treatment (MMT) for controlling infectious diseases have been confirmed, treatment failure has been seen in a large range of the patients. This review addresses the importance of a less attentive behavioural approach in reducing treatment withdrawal. The executive protocol, the outcomes and challenges, and the benefits of this approach are debatable.

Targeting Phosphodiesterases in Pharmacotherapy for Substance Dependence

Substance dependence is a chronic relapsing brain disorder associated with adaptational changes in synaptic plasticity and neuronal functions. The high levels of substance consumption and relapse rate suggest more reliable medications are in need to better address the underlying causes of this disease. It has been well established that the intracellular second messengers cyclic AMP (cAMP) and cyclic GMP (cGMP) and their signaling systems play an important role in the molecular mechanisms of substance taking behaviors. On this basis, the phosphodiesterase (PDE) superfamily, which crucially controls cyclic nucleotide levels by catalyzing their hydrolysis, has been proposed as a novel class of therapeutic targets for substance use disorders. This chapter reviews the expression patterns of PDEs in the brain with regard to neural structures underlying the dependent process and highlights available evidence for a modulatory role of PDEs in substance dependence.

Behavioral approach and orbitofrontal cortical activity during decision-making in substance dependence

Behavioral approach, defined as behavior directed toward a reward or novel stimulus, when elevated, may increase one's vulnerability to substance use disorder. Behavioral approach has been associated with relatively greater left compared to right frontal activity; behavioral inhibition may be associated with relatively greater right compared to left frontal brain activity. We hypothesized that substance dependent individuals (SDI) would have higher behavioral approach than controls and greater prefrontal cortical activity during decision-making involving reward. We hypothesized that behavioral approach would correlate with left frontal activity during decision-making and that the correlation would be stronger in SDI than controls. 31 SDI and 21 controls completed the Behavioral Inhibition System/Behavioral Approach System (BIS/BAS) scales and performed a decision-making task during fMRI. Orbitofrontal (OFC) and dorsolateral prefrontal activity were correlated with BIS and BAS scores. Compared to controls, SDI had higher BAS Fun Seeking scores (p<0.001) and worse decision-making performance (p=0.004). BAS Fun Seeking correlated with left OFC activity during decision-making across group (r=0.444, p<0.003). The correlation did not differ by group. There was no correlation between BIS and right frontal activity. Left OFC may play a role in reward-related decision-making in substance use disorder especially in individuals with high behavioral approach.

Impaired Decision-Making, Higher Impulsivity, and Drug Severity in Substance Dependence and Pathological Gambling

OBJECTIVES

Substance use disorder is characterized by impaired decision making, impulsivity, and risk taking. Pathological gambling shares many of these characteristics, and having both diagnoses may be associated with greater problems than either diagnosis alone. We investigated whether among substance-dependent individuals, comorbid pathological gambling would be associated with worse decision making, greater impulsivity, risk taking, and drug severity.

METHODS

Ninety-six substance-dependent individuals were recruited from a residential treatment program and divided into 1 of the 2 groups depending on whether they met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for pathological gambling (SDPG, n = 26) or not (SD, n = 70). Ninety-two controls were recruited from the community. Participants completed a decision-making task (modified Iowa Gambling Task), measures of impulsivity (Barratt Impulsivity Scale and Delay Discounting), and risk taking (Balloon Analog Risk Task). Decision making was analyzed using a computational model. We tested for group differences using analysis of covariance or Kruskal-Wallis and appropriate post-hoc tests.

RESULTS

The groups differed in decision-making parameters (P < 0.001) and self-reported impulsivity (P < 0.001). All post-hoc comparisons were significant on these measures, and indicated stepwise changes in controls, followed by SD, followed by SDPG, with SDPG performing worse on decision making and being more impulsive. Compared with SD, SDPG had greater drug severity (P < 0.001). No group differences were observed in delay discounting or risk taking.

CONCLUSIONS

Compared with individuals with substance dependence without pathological gambling, those with both disorders demonstrated worse decision making and significantly more drug-related symptoms. When evaluating patients with substance dependence, clinicians should consider diagnostic assessments for gambling, as the co-occurrence of both disorders may impact clinical characteristics.

Brain Cortical Thickness Differences in Adolescent Females with Substance Use Disorders

Some youths develop multiple substance use disorders early in adolescence and have severe, persistent courses. Such youths often exhibit impulsivity, risk-taking, and problems of inhibition. However, relatively little is known about the possible brain bases of these behavioral traits, especially among females.

Influence of dorsolateral prefrontal cortex and ventral striatum on risk avoidance in addiction: a mediation analysis

BACKGROUND

Alterations in frontal and striatal function are hypothesized to underlie risky decision making in drug users, but how these regions interact to affect behavior is incompletely understood. We used mediation analysis to investigate how prefrontal cortex and ventral striatum together influence risk avoidance in abstinent drug users.

METHOD

Thirty-seven abstinent substance-dependent individuals (SDI) and 43 controls underwent fMRI while performing a decision-making task involving risk and reward. Analyses of a priori regions-of-interest tested whether activity in dorsolateral prefrontal cortex (DLPFC) and ventral striatum (VST) explained group differences in risk avoidance. Whole-brain analysis was conducted to identify brain regions influencing the negative VST-risk avoidance relationship.

RESULTS

Right DLPFC (RDLPFC) positively mediated the group-risk avoidance relationship (p < 0.05); RDLPFC activity was higher in SDI and predicted higher risk avoidance across groups, controlling for SDI vs.

CONTROLS

Conversely, VST activity negatively influenced risk avoidance (p < 0.05); it was higher in SDI, and predicted lower risk avoidance. Whole-brain analysis revealed that, across group, RDLPFC and left temporal-parietal junction positively (p ≤ 0.001) while right thalamus and left middle frontal gyrus negatively (p < 0.005) mediated the VST activity-risk avoidance relationship.

CONCLUSION

RDLPFC activity mediated less risky decision making while VST mediated more risky decision making across drug users and controls. These results suggest a dual pathway underlying decision making, which, if imbalanced, may adversely influence choices involving risk. Modeling contributions of multiple brain systems to behavior through mediation analysis could lead to a better understanding of mechanisms of behavior and suggest neuromodulatory treatments for addiction.

Neuronal correlates of risk-seeking attitudes to anticipated losses in binge drinkers

BACKGROUND

Abnormal decision making under risk is associated with a number of psychiatric disorders. Here, we focus on binge drinkers (BD), characterized by repeated episodes of heavy alcohol intoxication. Previous studies suggest a decreased sensitivity to aversive conditioning in BD. Here, we asked whether BD might be characterized by enhanced risk seeking related to decreased sensitivity to the anticipation of negative outcomes.

METHODS

Using an anticipatory risk-taking task (40 BD and 70 healthy volunteers) and an adapted version of this task for functional magnetic resonance imaging (21 BD and 21 healthy volunteers), we assessed sensitivity to reward and loss across risk probabilities.

RESULTS

In the behavioral task, BD showed a higher number of risky choices in high-risk losses. In the neuroimaging task, the high-risk attitude in the loss condition was associated with greater activity in dorsolateral prefrontal, lateral orbitofrontal, and superior parietal cortices in BD. Explicit exposure of BD to the probability and magnitude of loss, via introduction of feedback, resulted in a subsequent decrease in risky choices. This change in risk attitude in BD was associated with greater activity in inferior frontal gyrus, which also correlated with the percentage of decrease in risky choices after feedback presentation, suggesting a possible role for cognitive control toward risk-seeking attitudes.

CONCLUSIONS

Our findings suggest that a decrease in sensitivity to the anticipation of high-risk negative outcomes might underlie BD behavior. Presentation of explicit feedback of probability and loss in BD can potentially modify risk-taking attitudes, which have important public health implications and suggest possible therapeutic targets.

Dissecting impulsivity and its relationships to drug addictions

Addictions are often characterized as forms of impulsive behavior. That said, it is often noted that impulsivity is a multidimensional construct, spanning several psychological domains. This review describes the relationship between varieties of impulsivity and addiction-related behaviors, the nature of the causal relationship between the two, and the underlying neurobiological mechanisms that promote impulsive behaviors. We conclude that the available data strongly support the notion that impulsivity is both a risk factor for, and a consequence of, drug and alcohol consumption. While the evidence indicating that subtypes of impulsive behavior are uniquely informative--either biologically or with respect to their relationships to addictions--is convincing, multiple lines of study link distinct subtypes of impulsivity to low dopamine D2 receptor function and perturbed serotonergic transmission, revealing shared mechanisms between the subtypes. Therefore, a common biological framework involving monoaminergic transmitters in key frontostriatal circuits may link multiple forms of impulsivity to drug self-administration and addiction-related behaviors. Further dissection of these relationships is needed before the next phase of genetic and genomic discovery will be able to reveal the biological sources of the vulnerability for addiction indexed by impulsivity.

Temporal profile of fronto-striatal-limbic activity during implicit decisions in drug dependence

BACKGROUND

Substance dependence is associated with impaired decision-making and altered fronto-striatal-limbic activity. Both greater and lesser brain activity have been reported in drug users compared to controls during decision-making. Inconsistent results might be explained by group differences in the temporal profile of the functional magnetic resonance imaging (fMRI) response. While most previous studies model a canonical hemodynamic response, a finite impulse response (FIR) model measures fMRI signal at discrete time points without assuming a temporal profile. We compared brain activity during decision-making and feedback in substance users and controls using two models: a canonical hemodynamic response function (HRF) and a FIR model.

METHODS

37 substance-dependent individuals (SDI) and 43 controls performed event-related decision-making during fMRI scanning. Brain activity was compared across group using canonical HRF and FIR models.

RESULTS

Compared to controls, SDI were impaired at decision-making. The canonical HRF model showed that SDI had significantly greater fronto-striatal-limbic activity during decisions and less activity during feedback than controls. The FIR model confirmed greater activity in SDI during decisions. However, lower activity in SDI during feedback corresponded to a lower post-stimulus undershoot of the hemodynamic response.

CONCLUSIONS

Greater activity in fronto-striatal-limbic pathways in SDI compared to controls is consistent with prior work, further supporting the hypothesis that abnormalities in these circuits underlie impaired decision-making. We demonstrate for the first time using FIR analysis that lower activity during feedback may simply reflect the tail end of the hemodynamic response to decision, the post-stimulus undershoot, rather than an actual difference in feedback response.

Reduced neural tracking of prediction error in substance-dependent individuals

OBJECTIVE

Substance-dependent individuals make poor decisions on the Iowa Gambling Task, a reward-related decision-making task that involves risk and uncertainty. Task performance depends on several factors, including how sensitive individuals are to feedback and how well they learn based on such feedback. A physiological signal that guides decision making based on feedback is prediction error. The authors investigated whether disruptions in the neural systems underlying prediction error processing in substance-dependent individuals could account for decision-making performance on a modified Iowa Gambling Task.

METHODS

Thirty-two substance-dependent individuals and 30 healthy comparison subjects played a modified version of the Iowa Gambling Task during MR scanning. Trial-to-trial behavior and functional MRI (fMRI) blood-oxygen-level-dependent (BOLD) signal were analyzed using a computational model of prediction error based on internal expectancies. The authors investigated how well BOLD signal tracked prediction error in the striatum and the orbitofrontal cortex as well as over the whole brain in patients relative to comparison subjects.

RESULTS

Compared with healthy subjects, substance-dependent patients were less sensitive to loss compared with gain, made less consistent choices, and performed worse on the modified Iowa Gambling Task. The ventral striatum and medial orbitofrontal cortex did not track prediction error as strongly in patients as in healthy subjects.

CONCLUSIONS

Weaker tracking of prediction error in substance-dependent relative to healthy individuals suggests that altered frontal-striatal error learning signals may underlie decision-making impairments in drug abusers. Computational fMRI may help bridge the knowledge gap between physiology and behavior to inform research aimed at substance abuse treatment.

Insula and orbitofrontal cortical morphology in substance dependence is modulated by sex

BACKGROUND AND PURPOSE

Frontolimbic circuits are involved in learning and decision-making processes thought to be affected in substance-dependent individuals. We investigated frontolimbic cortical morphometry in substance-dependent men and women and determined whether morphometric measurements correlated with decision-making performance.

MATERIALS AND METHODS

Twenty-eight abstinent SDI (17 men/11 women) were compared with 28 controls (13 men/15 women). Cortical thicknesses and volumes were computed by using FreeSurfer. After controlling for age and intracranial volume, group and sex effects were analyzed in 3 a priori regions of interest: the insula, orbitofrontal cortex, and anterior cingulate cortex by using analysis of covariance. A secondary whole-brain analysis was conducted to verify region-of-interest results and to explore potential differences in other brain regions.

RESULTS

Region-of-interest analyses revealed a main effect of group on the left insula cortex, which was thinner in SDI compared with controls (P = .02). There was a group by sex interaction on bilateral insula volume (left, P = .02; right, P = .001) and right insula cortical thickness (P = .007). Compared with same-sex controls, female SDI had smaller insulae, whereas male SDI had larger insulae. Neither ACC nor OFC significantly differed across group. Performance on a decision-making task was better in controls than SDI and correlated with OFC measurements in the controls.

CONCLUSIONS

SDI and controls differed in insula morphology, and those differences were modulated by sex. No group differences in OFC were observed, but OFC measurements correlated with negative-reinforcement learning in controls. These preliminary results are consistent with a hypothesis that frontolimbic pathways may be involved in behaviors related to substance dependence.