Disturbances across whole brain networks during reward anticipation in an abstinent addiction population

Art therapy's engagement of brain networks for enduring recovery from addiction

The field of addiction in its priority to save lives has emphasized harm reduction and medication therapies that have taken precedence over counseling and psychotherapy. The extensive mental health needs, traumatic histories and cognitive challenges of this population call for more availability of all treatments, but also in-depth treatment for the causes of the addiction. The prevalence of trauma is examined with regard to the challenge it presents in treatment for substance use disorder (SUD), and other comorbidities. Two case examples are offered that exemplify how art therapy expedites key information about underlying trauma. Art therapy is proposed as a treatment approach for SUD for its apparent activation of key neural networks that are also impacted by trauma, and its usefulness in engaging those who have cognitive challenges experientially. Quantitative research is cited that suggests art therapy's activation of the reward system, which may make art therapy useful in treating the stress and inhibition coefficients of addiction that map to neural networks of addiction. The need for additional empirical research is cited that may improve the efficiency and effectiveness of art therapy and mental health treatment.

Alterations of gray matter asymmetry in internet gaming disorder

Structural asymmetry is a subtle but pervasive property of the human brain, which has been found altered in various psychiatric and neurocognitive disorders. However, little is known regarding potential alterations of structural asymmetry underlying internet gaming disorder (IGD). Therefore, this study aimed to investigate the structural features of gray matter asymmetry in IGD. High-resolution structural magnetic resonance imaging data were collected from 104 individuals with IGD and 104 recreational game users (RGUs). We applied a whole-brain voxel-based asymmetry (VBA) approach to determine the asymmetrical aberrations of gray matter in relation to IGD. Furthermore, the local abnormalities of structural asymmetry were employed as features to examine the effect of classification using a support vector machine (SVM). The results indicated that individuals with IGD as compared to RGUs showed asymmetrical alterations of gray matter in the medial prefrontal cortex (mPFC), orbitofrontal cortex, precuneus, middle temporal gyrus, superior parietal lobule and inferior temporal gyrus, regions implicated in hedonic motivation, self-reflection, information integration and visuospatial attention processing. Moreover, these atypical asymmetrical features can distinguish IGD subjects from RGUs with high accuracy. These results suggested that disrupted structural asymmetry of motivational reward, visuospatial and default mode circuits might be potential biomarkers for identifying pathological gaming dependence. These findings extended our understanding of structural underpinnings of IGD and provided new insights for developing effective interventions to alleviate compulsive gaming usage.

Reduced brain connectivity underlying value-based choices and outcomes in stimulant use disorder

BACKGROUND

Patients with stimulant use disorder (SUD) show impairments when making value-based choices that are associated with disruptions in neural processing across brain networks. Making optimal choices requires learning from outcomes to update knowledge and further optimise ongoing behaviour. The optimal functioning of neural systems that underpin the ability to make favourable choices is an essential component for life functioning, and successful recovery in patients with SUD. Therefore, we sought to investigate the neural processes that underpin value-based choices in SUD patients. We hypothesise that patients with SUD have reduced functional connectivity while making financial choices during a probabilistic reinforcement learning task.

METHODS

We investigated connectivity associated with loss and reward value-based choices and their outcomes in patients with SUD and healthy control participants during a pharmacological magnetic resonance imaging study. Participants received a single dose of a dopamine receptor agonist, pramipexole, and a dopamine receptor antagonist, amisulpride, in a randomised, double-blind, placebo-controlled, balanced, crossover design. Functional task-related connectivity was analysed taking a whole brain connectomics approach to identify networks that are differentially modulated by dopaminergic receptor functioning.

RESULTS

SUD patients showed widespread reductions in connectivity during both reward and loss value-based choices and outcomes, which were negatively correlated with the duration of stimulant drug use. Disturbances to functional brain connectivity in SUD patients during task performance were not modulated acutely by either amisulpride or pramipexole.

CONCLUSIONS

Reductions in brain connectivity, particularly when making value-based choices and processing outcomes, may underlie learning impairments in SUD patients. Given that acute dopaminergic modulation did not improve brain connectivity impairments in SUD patients, it is likely that alternative treatments are needed.

The Modulatory Effects of Atomoxetine on Aberrant Connectivity During Attentional Processing in Cocaine Use Disorder

BACKGROUND

Cocaine use disorder is associated with cognitive deficits that reflect dysfunctional processing across neural systems. Because there are currently no approved medications, treatment centers provide behavioral interventions that have only short-term efficacy. This suggests that behavioral interventions are not sufficient by themselves to lead to the maintenance of abstinence in patients with cocaine use disorder. Self-control, which includes the regulation of attention, is critical for dealing with many daily challenges that would benefit from medication interventions that can ameliorate cognitive neural disturbances.

METHODS

To address this important clinical gap, we conducted a randomized, double-blind, placebo-controlled, crossover design study in patients with cocaine use disorder (n = 23) and healthy control participants (n = 28). We assessed the modulatory effects of acute atomoxetine (40 mg) on attention and conflict monitoring and their associated neural activation and connectivity correlates during performance on the Eriksen flanker task. The Eriksen flanker task examines basic attentional processing using congruent stimuli and the effects of conflict monitoring and response inhibition using incongruent stimuli, the latter of which necessitates the executive control of attention.

RESULTS

We found that atomoxetine improved task accuracy only in the cocaine group but modulated connectivity within distinct brain networks in both groups during congruent trials. During incongruent trials, the cocaine group showed increased task-related activation in the right inferior frontal and anterior cingulate gyri, as well as greater network connectivity than the control group across treatments.

CONCLUSIONS

The findings of the current study support a modulatory effect of acute atomoxetine on attention and associated connectivity in cocaine use disorder.

Psychedelic therapy in the treatment of addiction: the past, present and future

Psychedelic therapy has witnessed a resurgence in interest in the last decade from the scientific and medical communities with evidence now building for its safety and efficacy in treating a range of psychiatric disorders including addiction. In this review we will chart the research investigating the role of these interventions in individuals with addiction beginning with an overview of the current socioeconomic impact of addiction, treatment options, and outcomes. We will start by examining historical studies from the first psychedelic research era of the mid-late 1900s, followed by an overview of the available real-world evidence gathered from naturalistic, observational, and survey-based studies. We will then cover modern-day clinical trials of psychedelic therapies in addiction from first-in-human to phase II clinical trials. Finally, we will provide an overview of the different translational human neuropsychopharmacology techniques, including functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), that can be applied to foster a mechanistic understanding of therapeutic mechanisms. A more granular understanding of the treatment effects of psychedelics will facilitate the optimisation of the psychedelic therapy drug development landscape, and ultimately improve patient outcomes.

A meta-analysis of the neural substrates of monetary reward anticipation and outcome in alcohol use disorder

The capacity to anticipate and detect rewarding outcomes is fundamental for the development of adaptive decision-making and goal-oriented behavior. Delineating the neural correlates of different stages of reward processing is imperative for understanding the neurobiological mechanism underlying alcohol use disorder (AUD). To examine the neural correlates of monetary anticipation and outcome in AUD patients, we performed two separate voxel-wise meta-analyses of functional neuroimaging studies, including 12 studies investigating reward anticipation and 7 studies investigating reward outcome using the monetary incentive delay task. During the anticipation stage, AUD patients displayed decreased activation in response to monetary cues in mesocortical-limbic circuits and sensory areas, including the ventral striatum (VS), insula, hippocampus, inferior occipital gyrus, supramarginal gyrus, lingual gyrus and fusiform gyrus. During the outcome stage, AUD patients exhibited reduced activation in the dorsal striatum, VS and insula, and increased activation in the orbital frontal cortex and medial temporal area. Our findings suggest that different activation patterns are associated with nondrug rewards during different reward processing stages, potentially reflecting a changed sensitivity to monetary reward in AUD.

Reduced neural functional connectivity during working memory performance in methamphetamine use disorder

BACKGROUND

Methamphetamine misuse, a surging cause of morbidity and mortality worldwide, identifies Methamphetamine Use Disorder (MUD) as a critical public health problem. Treatment for MUD typically is sought during early abstinence when patients are experiencing cognitive difficulties that may hamper their engagement in treatment and recovery. Cognitive difficulties, particularly those that involve executive functions, likely reflect disruptions in neural functioning involving multiple brain areas and circuits.

METHODS

To extend knowledge in this area, we compared individuals with MUD (MUD group, n = 30) in early abstinence (3-11 days abstinent) with a healthy control group (HC, n = 33) on brain activation and network connectivity and topology, using functional magnetic resonance imaging (fMRI) during performance on an N-back working memory task. The N-back task involves the maintenance and manipulation of information in short-term memory and engages multiple neural processes related to executive functioning. The task was administered at two working-memory difficulty loads (1-back and 2-back).

RESULTS

Compared with the HC group, the MUD group had worse task performance but no differences in task-related brain activation. Network-based statistics analyses, however, revealed that the MUD group exhibited less functional network connectivity at both difficulty loads of the N-back task than the HC group. Additional graph theory analyses showed that path lengths were longer, and clustering was lower across these networks, which also exhibited disrupted small-world properties in the MUD group.

CONCLUSION

These results suggest a decoupling in network dynamics that may underlie deficits in cognition during early abstinence in MUD patients.

Abnormal Brain Networks Related to Drug and Nondrug Reward Anticipation and Outcome Processing in Stimulant Use Disorder: A Functional Connectomics Approach

BACKGROUND

Drug addiction is associated with blunted neural responses to nondrug rewards, such as money, but heightened responses to drug cues that predict drug-reward outcomes. This dissociation underscores the role of incentive context in the attribution of motivational salience, which may reflect a narrowing toward drug-related goals. This hypothesis, however, has scarcely been investigated.

METHODS

To address this important scientific gap, the current study performed an empirical assessment of differences in salience attribution by comparing patients with stimulant use disorder (SUD) (n = 41) with control participants (n = 48) on network connectivity related to anticipation and outcome processing using a modified monetary incentive delay task. We hypothesized increased task-related activation and connectivity to drug rewards in patients with SUD, and reduced task-related activation and connectivity to monetary rewards during incentive processing across brain networks.

RESULTS

In the presence of behavioral and regional brain activation similarities, we found that patients with SUD showed significantly less connectivity involving three separate distributed networks during monetary reward anticipation, and drug and monetary reward outcome processing. No group connectivity differences for drug reward anticipation were identified. Additional graph theory analyses revealed that patients with SUD had longer path lengths across these networks, all of which positively correlated with the duration of stimulant drug use.

CONCLUSIONS

Specific disruptions in connectivity in networks related to the anticipation of nondrug reward together with more general dysconnectivity in the processing of rewarding outcomes suggest an insensitivity to consequences. These observations support the notion of a predominance of habitual control in patients with SUD.

Anomalies in global network connectivity associated with early recovery from alcohol dependence: A network transcranial magnetic stimulation and electroencephalography study

Although previous research in alcohol dependent populations identified alterations within local structures of the addiction ‘reward’ circuitry, there is limited research into global features of this network, especially in early recovery. Transcranial magnetic stimulation (TMS) is capable of non‐invasively perturbing the brain network while electroencephalography (EEG) measures the network response. The current study is the first to apply a TMS inhibitory paradigm while utilising network science (graph theory) to quantify network anomalies associated with alcohol dependence. Eleven individuals with alcohol‐dependence (ALD) in early recovery and 16 healthy controls (HC) were administered 75 single pulses and 75 paired‐pulses (inhibitory paradigm) to both the left and right prefrontal cortex (PFC). For each participant, Pearson cross‐correlation was applied to the EEG data and correlation matrices constructed. Global network measures (mean degree, clustering coefficient, local efficiency and global efficiency) were extracted for comparison between groups. Following administration of the inhibitory paired‐pulse TMS to the left PFC, the ALD group exhibited altered mean degree, clustering coefficient, local efficiency and global efficiency compared to HC. Decreases in local efficiency increased the prediction of being in the ALD group, while all network metrics (following paired‐pulse left TMS) were able to adequately discriminate between the groups. In the ALD group, reduced mean degree and global clustering was associated with increased severity of past alcohol use. Our study provides preliminary evidence of altered network topology in patients with alcohol dependence in early recovery. Network anomalies were predictive of high alcohol use and correlated with clinical features of alcohol dependence. Further research using this novel brain mapping technique may identify useful network biomarkers of alcohol dependence and recovery.

The neurobiology of drug addiction: cross-species insights into the dysfunction and recovery of the prefrontal cortex

A growing preclinical and clinical body of work on the effects of chronic drug use and drug addiction has extended the scope of inquiry from the putative reward-related subcortical mechanisms to higher-order executive functions as regulated by the prefrontal cortex. Here we review the neuroimaging evidence in humans and non-human primates to demonstrate the involvement of the prefrontal cortex in emotional, cognitive, and behavioral alterations in drug addiction, with particular attention to the impaired response inhibition and salience attribution (iRISA) framework. In support of iRISA, functional and structural neuroimaging studies document a role for the prefrontal cortex in assigning excessive salience to drug over non-drug-related processes with concomitant lapses in self-control, and deficits in reward-related decision-making and insight into illness. Importantly, converging insights from human and non-human primate studies suggest a causal relationship between drug addiction and prefrontal insult, indicating that chronic drug use causes the prefrontal cortex damage that underlies iRISA while changes with abstinence and recovery with treatment suggest plasticity of these same brain regions and functions. We further dissect the overlapping and distinct characteristics of drug classes, potential biomarkers that inform vulnerability and resilience, and advancements in cutting-edge psychological and neuromodulatory treatment strategies, providing a comprehensive landscape of the human and non-human primate drug addiction literature as it relates to the prefrontal cortex.

Characterizing reward system neural trajectories from adolescence to young adulthood

Mixed findings exist in studies comparing brain responses to reward in adolescents and adults. Here we examined the trajectories of brain response, functional connectivity and task-modulated network properties during reward processing with a large-sample longitudinal design. Participants from the IMAGEN study performed a Monetary Incentive Delay task during fMRI at timepoint 1 (T1; n = 1304, mean age=14.44 years old) and timepoint 2 (T2; n = 1241, mean age=19.09 years). The Alcohol Use Disorders Identification Test (AUDIT) was administrated at both T1 and T2 to assess a participant’s alcohol use during the past year. Voxel-wise linear mixed effect models were used to compare whole brain response as well as functional connectivity of the ventral striatum (VS) during reward anticipation (large reward vs no-reward cue) between T1 and T2. In addition, task-modulated networks were constructed using generalized psychophysiological interaction analysis and summarized with graph theory metrics. To explore alcohol use in relation to development, participants with no/low alcohol use at T1 but increased alcohol use to hazardous use level at T2 (i.e., participants with AUDIT≤2 at T1 and ≥8 at T2) were compared against those with consistently low scores (i.e., participants with AUDIT≤2 at T1 and ≤7 at T2). Across the whole sample, lower brain response during reward anticipation was observed at T2 compared with T1 in bilateral caudate nucleus, VS, thalamus, midbrain, dorsal anterior cingulate as well as left precentral and postcentral gyrus. Conversely, greater response was observed bilaterally in the inferior and middle frontal gyrus and right precentral and postcentral gyrus at T2 (vs. T1). Increased functional connectivity with VS was found in frontal, temporal, parietal and occipital regions at T2. Graph theory metrics of the task-modulated network showed higher inter-regional connectivity and topological efficiency at T2. Interactive effects between time (T1 vs. T2) and alcohol use group (low vs. high) on the functional connectivity were observed between left middle temporal gyrus and right VS and the characteristic shortest path length of the task-modulated networks. Collectively, these results demonstrate the utility of the MID task as a probe of typical brain response and network properties during development and of differences in these features related to adolescent drinking, a reward-related behaviour associated with heightened risk for future negative health outcomes.

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Imaging data during reward anticipation at T1 (age 14) and T2 (age 19) was compared.

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Brain response decreased in subcortical areas and increased in cortical areas at T2.

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Functional connectivity (FC) with the ventral striatum increased at T2.

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Topological efficiency of task-modulated network increased at T2.

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The developmental pattern was altered in those who increased drinking most at T2.

Dopamine and relapse to drug seeking

The actions of dopamine are essential to relapse to drug seeking but we still lack a precise understanding of how dopamine achieves these effects. Here we review recent advances from animal models in understanding how dopamine controls relapse to drug seeking. These advances have been enabled by important developments in understanding the basic neurochemical, molecular, anatomical, physiological and functional properties of the major dopamine pathways in the mammalian brain. The literature shows that although different forms of relapse to seeking different drugs of abuse each depend on dopamine, there are distinct dopamine mechanisms for relapse. Different circuit-level mechanisms, different populations of dopamine neurons and different activity profiles within these dopamine neurons, are important for driving different forms of relapse. This diversity highlights the need to better understand when, where and how dopamine contributes to relapse behaviours.