The association between cue-reactivity in the precuneus and level of dependence on nicotine and alcohol

Altered individual gray matter structural covariance networks in early abstinence patients with alcohol dependence

While alterations in cortical thickness have been widely observed in individuals with alcohol dependence, knowledge about cortical thickness-based structural covariance networks is limited. This study aimed to explore the topological disorganization of structural covariance networks based on cortical thickness at the single-subject level among patients with alcohol dependence. Structural imaging data were obtained from 61 patients with alcohol dependence during early abstinence and 59 healthy controls. The single-subject structural covariance networks were constructed based on cortical thickness data from 68 brain regions and were analyzed using graph theory. The relationships between network architecture and clinical characteristics were further investigated using partial correlation analysis. In the structural covariance networks, both patients with alcohol dependence and healthy controls displayed small-world topology. However, compared to controls, alcohol-dependent individuals exhibited significantly altered global network properties characterized by greater normalized shortest path length, greater shortest path length, and lower global efficiency. Patients exhibited lower degree centrality and nodal efficiency, primarily in the right precuneus. Additionally, scores on the Alcohol Use Disorder Identification Test were negatively correlated with the degree centrality and nodal efficiency of the left middle temporal gyrus. The results of this correlation analysis did not survive after multiple comparisons in the exploratory analysis. Our findings may reveal alterations in the topological organization of gray matter networks in alcoholism patients, which may contribute to understanding the mechanisms of alcohol addiction from a network perspective.

Neural correlates of the addictions neuroclinical assessment (ANA) incentive salience factor among individuals with alcohol use disorder

The Addictions Neuroclinical Assessment (ANA) is a recently-developed framework offering a more holistic understanding of three neurofunctional and behavioral domains that reflect the neurobiological dysfunction seen in alcohol use disorder (AUD). While the ANA domains have been well-validated across independent laboratories, there is a critical need to identify neural markers that subserve the proposed neurofunctional domains. The current study involves secondary data analysis of a two-week experimental medication trial of ibudilast (50 mg BID). Forty-five non-treatment-seeking participants with AUD (17F / 28 M) completed a battery of validated behavioral assessments forming the basis of their incentive salience factor score, computed via factor analysis, as well as a functional neuroimaging (fMRI) task assessing their neural reactivity to visual alcohol cues after being on placebo or ibudilast for 7 days. General linear models were conducted to examine the relationship between incentive salience and neural alcohol cue-reactivity in the ventral and dorsal stratum. Whole-brain generalized linear model analyses were conducted to examine associations between neural alcohol cue-reactivity and incentive salience. Age, sex, medication, and smoking status were included as covariates. Incentive salience was not associated with cue-elicited activation in the dorsal or ventral striatum. Incentive salience was significantly positively correlated (p < 0.05) with alcohol cue-elicited brain activation in reward-learning and affective regions including the insula and posterior cingulate cortices, bilateral precuneus, and bilateral precentral gyri. The ANA incentive salience factor is reflected in brain circuitry important for reward learning and emotion processing. Identifying a sub-phenotype of AUD characterized by increased incentive salience to alcohol cues allows for precision medicine approaches, i.e. treatments specifically targeting craving and reward from alcohol use. This study serves as a preliminary bio-behavioral validation for the incentive salience factor of the ANA. Further studies validating the neural correlates of other ANA factors, as well as replication in larger samples, appear warranted.

Reductions in WHO risk drinking levels correlate with alcohol craving among individuals with alcohol use disorder

BACKGROUND

Abstinence has historically been considered the preferred goal of alcohol use disorder (AUD) treatment. However, most individuals with AUD do not want to abstain and many are able to reduce their drinking successfully. Craving is often a target of pharmacological and behavioral interventions for AUD, and reductions in craving may signal recovery. Whether reductions in drinking during AUD treatment are associated with reductions in craving has not been well examined.

METHODS

We conducted secondary analyses of data from three AUD clinical trials (N's= 1327, 346, and 200). Drinking reductions from baseline to the end of treatment were measured as changes in World Health Organization (WHO) risk drinking levels; alcohol craving was measured using validated self-report measures. Regression analyses tested whether drinking reductions were associated with end-of-treatment craving reductions; moderation analyses tested whether associations between drinking reduction and end-of-treatment craving differed across AUD severity.

RESULTS

Reductions of at least 1 or at least 2 WHO risk drinking levels were associated with lower craving (all p's < 0.05). Results were substantively similar after removing abstainers at the end-of-treatment. Associations between drinking reductions and craving were generally not moderated by AUD severity.

CONCLUSIONS

Individuals with WHO risk drinking level reductions reported significantly lower craving, as compared to those who did not achieve meaningful reductions in drinking. The results demonstrate the utility of WHO risk drinking levels as AUD clinical trial endpoints and provide evidence that drinking reductions mitigate craving.

The effects of nicotine use during adolescence and young adulthood on gray matter cerebral blood flow estimates

Nicotine and tobacco product (NTP) use remains prevalent in adolescence/young adulthood. The effects of NTPs on markers of brain health during this vulnerable neurodevelopmental period remain largely unknown. This report investigates associations between NTP use and gray matter cerebral blood flow (CBF) in adolescents/young adults. Adolescent/young adult (16-22 years-old) nicotine users (NTP; N = 99; 40 women) and non-users (non-NTP; N = 95; 56 women) underwent neuroimaging sessions including anatomical and optimized pseudo-continuous arterial spin labeling scans. Groups were compared on whole-brain gray matter CBF estimates and their relation to age and sex at birth. Follow-up analyses assessed correlations between identified CBF clusters and NTP recency and dependence measures. Controlling for age and sex, the NTP vs. non-NTP contrast revealed a single cluster that survived thresholding which included portions of bilateral precuneus (voxel-wise alpha < 0.001, cluster-wise alpha < 0.05; ≥7 contiguous voxels). An interaction between NTP group contrast and age was observed in two clusters including regions of the left posterior cingulate (PCC)/lingual gyrus and right anterior cingulate cortex (ACC): non-NTP exhibited positive correlations between CBF and age in these clusters, whereas NTP exhibited negative correlations between CBF and age. Lower CBF from these three clusters correlated with urine cotinine (rs=-0.21 - - 0.16; ps < 0.04) and nicotine dependence severity (rs=-0.16 - - 0.13; ps < 0.07). This is the first investigation of gray matter CBF in adolescent/young adult users of NTPs. The results are consistent with literature on adults showing age- and nicotine-related declines in CBF and identify the precuneus/PCC and ACC as potential key regions subserving the development of nicotine dependence.

Explicit and implicit effects of gaming content on social media on the behavior of young adults

Excessive gameplay can have negative effects on both mental and physical health, especially among young people. Nowadays, social media platforms are bombarding users with gaming-related content daily. Understanding the effect of this content on people's behavior is essential to gain insight into problematic gaming habits. However, this issue is yet to be studied extensively. In this study, we examined how gaming-related content on social media affects young adults explicitly and implicitly. We studied 25 healthy young adults (average age 21.5 ± 2.2) who played online games casually and asked them to report their gaming desire. We also conducted an implicit association test (IAT) to measure their implicit attitudes toward gaming-related content. We also investigated the relationship between these measures and various psychological factors, such as personality traits, self-efficacy, impulsiveness, and cognitive flexibility. The results revealed that participants had a higher explicit gaming desire when exposed to gaming-related cues on social media than neutral cues. They also had a robust positive implicit attitude toward gaming-related content on social media. Explicit gaming desire was positively correlated with neuroticism levels. Furthermore, the IAT effect was negatively correlated with self-efficacy and cognitive flexibility levels. However, there were no significant correlations between explicit gaming desire/IAT effect and impulsiveness levels. These findings suggest that gaming-related content on social media can affect young adults' behavior both explicitly and implicitly, highlighting the need for further research to prevent gaming addiction in vulnerable individuals.

Disrupted white matter structural networks in individuals with alcohol dependence

Previous diffusion tensor imaging (DTI) studies have demonstrated widespread white matter microstructure damage in individuals with alcoholism. However, very little is known about the alterations in the topological architecture of white matter structural networks in alcohol dependence (AD). This study included 67 AD patients and 69 controls. The graph theoretical analysis method was applied to examine the topological organization of the white matter structural networks, and network-based statistics (NBS) were employed to detect structural connectivity alterations. Compared to controls, AD patients exhibited abnormal global network properties characterized by increased small-worldness, normalized clustering coefficient, clustering coefficient, and shortest path length; and decreased global efficiency and local efficiency. Further analyses revealed decreased nodal efficiency and degree centrality in AD patients mainly located in the default mode network (DMN), including the precuneus, anterior cingulate and paracingulate gyrus, median cingulate and paracingulate gyrus, posterior cingulate gyrus, and medial part of the superior frontal gyrus. Furthermore, based on NBS approaches, patients displayed weaker subnetwork connectivity mainly located in the region of the DMN. Additionally, altered network metrics were correlated with intelligence quotient (IQ) scores and global assessment function (GAF) scores. Our results may reveal the disruption of whole-brain white matter structural networks in AD individuals, which may contribute to our comprehension of the underlying pathophysiological mechanisms of alcohol addiction at the level of white matter structural networks.

Do mindfulness-based interventions change brain function in people with substance dependence? A systematic review of the fMRI evidence

BACKGROUND

Substance use disorders (SUDs) affect ~ 35 million people globally and are associated with strong cravings, stress, and brain alterations. Mindfulness-based interventions (MBIs) can mitigate the adverse psychosocial outcomes of SUDs, but the underlying neurobiology is unclear. Emerging findings were systematically synthesised from fMRI studies about MBI-associated changes in brain function in SUDs and their associations with mindfulness, drug quantity, and craving.

METHODS

PsycINFO, Medline, CINAHL, PubMed, Scopus, and Web of Science were searched. Seven studies met inclusion criteria.

RESULTS

Group by time effects indicated that MBIs in SUDs (6 tobacco and 1 opioid) were associated with changes in the function of brain pathways implicated in mindfulness and addiction (e.g., anterior cingulate cortex and striatum), which correlated with greater mindfulness, lower craving and drug quantity.

CONCLUSIONS

The evidence for fMRI-related changes with MBI in SUD is currently limited. More fMRI studies are required to identify how MBIs mitigate and facilitate recovery from aberrant brain functioning in SUDs.

Nicotine dependence and insula subregions: functional connectivity and cue-induced activation

Nicotine dependence is a major predictor of relapse in people with Tobacco Use Disorder (TUD). Accordingly, therapies that reduce nicotine dependence may promote sustained abstinence from smoking. The insular cortex has been identified as a promising target in brain-based therapies for TUD, and has three major sub-regions (ventral anterior, dorsal anterior, and posterior) that serve distinct functional networks. How these subregions and associated networks contribute to nicotine dependence is not well understood, and therefore was the focus of this study. Sixty individuals (28 women; 18-45 years old), who smoked cigarettes daily, rated their level of nicotine dependence (on the Fagerström Test for Nicotine Dependence) and, after abstaining from smoking overnight (~12 h), underwent functional magnetic resonance imaging (fMRI) in a resting state. A subset of these participants (N = 48) also completing a cue-induced craving task during fMRI. Correlations between nicotine dependence and resting-state functional connectivity (RSFC) and cue-induced activation of the major insular sub-regions were evaluated. Nicotine dependence was negatively correlated with connectivity of the left and right dorsal, and left ventral anterior insula with regions within the superior parietal lobule (SPL), including the left precuneus. No relationship between posterior insula connectivity and nicotine dependence was found. Cue-induced activation in the left dorsal anterior insula was positively associated with nicotine dependence and negatively associated with RSFC of the same region with SPL, suggesting that craving-related responsivity in this subregion was greater among participants who were more dependent. These results may inform therapeutic approaches, such as brain stimulation, which may elicit differential clinical outcomes (e.g., dependence, craving) depending on the insular subnetwork that is targeted.

Pain Catastrophizing Is Associated With Increased Alcohol Cue-Elicited Neural Activity Among Individuals With Alcohol Use Disorder

AIMS

The current study examined the association between pain catastrophizing and alcohol cue-elicited brain activation in individuals with alcohol use disorder (AUD).

METHODS

Non-treatment seeking heavy drinkers with AUD (n = 45; 28 males) completed self-report measures of pain catastrophizing and alcohol use/problems as part of a clinical trial of the neuroimmune modulator ibudilast. Participants were randomized to either placebo (n = 25) or ibudilast (n = 20) and completed an functional magnetic resonance imaging (fMRI) scan to assess neural activation to alcohol cues 1 week into the medication trial. Multiple linear regression examined whether pain catastrophizing predicted cue-induced activation in a priori regions of interest, namely the dorsal and ventral striatum (VS). An exploratory whole-brain analysis was conducted to assess the relationship between pain catastrophizing and neural alcohol cue reactivity.

RESULTS

Pain catastrophizing predicted greater cue-induced activation in the dorsal (b = 0.006; P = 0.03) but not VS controlling for medication. Pain catastrophizing was positively associated with neural activation to alcohol cues in regions including the bilateral thalamus, left precuneus and left frontal pole.

CONCLUSION

Greater pain catastrophizing is associated with greater cue-induced neural activation in brain regions sub-serving habits and compulsive alcohol use. These findings provide initial support for a neural mechanism by which pain catastrophizing may drive alcohol craving among individuals with AUD.

The effects of nalmefene on the impulsive and reflective system in alcohol use disorder: A resting-state fMRI study

RATIONALE

Central aspects of alcohol use disorder (AUD) are the irresistible desire for alcohol and impaired control over its intake. According to the triadic neurocognitive model of addiction, this arises from aberrant functioning of different neural and cognitive systems: an impulsive system, a reflective system, and the abnormal dynamics between both systems based on an insular-dependent system.

OBJECTIVES

In this study, we examined the effects of a single dose of nalmefene on resting-state functional connectivity (rsFC) patterns within and between these addiction-related neural systems in AUD.

METHODS

Non-treatment seeking participants with AUD (N = 17; 19-66 years, 6 female) took part in a randomized, placebo-controlled, double-blind, crossover study and received either a single dose of 18 mg nalmefene or a placebo. Using seed-based correlation analyses on resting-state functional magnetic resonance imaging data, we examined the effects of nalmefene on key nodes related to the (1) impulsive system; (2) reflective system; (3) salience network; and (4) default mode network.

RESULTS

Under nalmefene, participants showed reduced rsFC between components of the impulsive system (Nucleus accumbens-putamen/pallidum/insula). Reduced rsFC was found between elements of the reflective system and impulsive system (orbitofrontal cortex-insula/putamen/pallidum), salience network (orbitofrontal cortex-insula/inferior frontal gyrus), and default mode network (lateral prefrontal cortex-precuneus/cuneus). Components of the salience network showed both increased (anterior cingulate cortex) and decreased (insular cortex) rsFC to elements of the reflective system.

CONCLUSION

A single dose of nalmefene impacts rsFC and alters the interaction between key nodes of addiction-related neural systems in non-treatment seeking participants with AUD. Nalmefene may normalize rsFC patterns by weakening the impulsive system while strengthening the reflective system.

TRIAL REGISTRATION

clinicaltrials.gov: NCT02372318.

Effects of Cigarette Smoking on Resting-State Functional Connectivity of the Nucleus Basalis of Meynert in Mild Cognitive Impairment

Background: Mild cognitive impairment (MCI) is the prodromal phase of Alzheimer’s disease (AD) and has a high risk of progression to AD. Cigarette smoking is one of the important modifiable risk factors in AD progression. Cholinergic dysfunction, especially the nucleus basalis of Meynert (NBM), is the converging target connecting smoking and AD. However, how cigarette smoking affects NBM connectivity in MCI remains unclear.

Objective: This study aimed to evaluate the interaction effects of condition (non-smoking vs. smoking) and diagnosis [cognitively normal (CN) vs. MCI] based on the resting-state functional connectivity (rsFC) of the NBM.

Methods: After propensity score matching, we included 86 non-smoking CN, 44 smoking CN, 62 non-smoking MCI, and 32 smoking MCI. All subjects underwent structural and functional magnetic resonance imaging scans and neuropsychological tests. The seed-based rsFC of the NBM with the whole-brain voxel was calculated. Furthermore, the mixed effect analysis was performed to explore the interaction effects between condition and diagnosis on rsFC of the NBM.

Results: The interaction effects of condition × diagnosis on rsFC of the NBM were observed in the bilateral prefrontal cortex (PFC), bilateral supplementary motor area (SMA), and right precuneus/middle occipital gyrus (MOG). Specifically, the smoking CN showed decreased rsFC between left NBM and PFC and increased rsFC between left NBM and SMA compared with non-smoking CN and smoking MCI. The smoking MCI showed reduced rsFC between right NBM and precuneus/MOG compared with non-smoking MCI. Additionally, rsFC between the NBM and SMA showed a significant negative correlation with Wechsler Memory Scale-Logical Memory (WMS-LM) immediate recall in smoking CN (r = −0.321, p = 0.041).

Conclusion: Our findings indicate that chronic nicotine exposure through smoking may lead to functional connectivity disruption between the NBM and precuneus in MCI patients. The distinct alteration patterns on NBM connectivity in CN smokers and MCI smokers suggest that cigarette smoking has different influences on normal and impaired cognition.

Imbalanced sensitivities to primary and secondary rewards in internet gaming disorder

BACKGROUND

Internet gaming disorder (IGD) is a type of behavioral addiction characterized by poorly controlled and interfering patterns of game playing. Studies have suggested that the IGD is usually accompanied by increased desire or craving for gaming, suggesting that secondary rewards related to gaming may become more salient than those for primary rewards like food. However, this hypothesis has not been formally tested and potential neural mechanisms remain unclear.

METHODS

This is a functional magnetic resonance imaging (fMRI) study. Twenty-one IGD subjects and 23 matched individuals with recreational game use (RGU) were scanned when exposed to gaming (secondary rewards), food (primary rewards) and neutral cues. Group-by-cue-type interaction analyses and subsequent within-group analyses for fMRI data were performed and seed-based functional connectivity (FC) analyses explored further potential neural features.

RESULTS

IGD subjects' subjective craving responses to gaming cues were higher than to food cues, while the opposite was observed in RGU subjects. Group-by-cue interaction effects implicated the precuneus and precuneus-caudate FC. Simple effect analysis showed that for IGD subjects, gaming-related cues elicited higher FC in precuneus-caudate relationships than did food-related cues. In the RGU subjects, the opposite was observed. Significant correlations were found between brain features and craving scores.

CONCLUSIONS

These results support the hypothesis regarding imbalances in sensitivities to different types of reward in IGD, and suggest neural mechanisms by which craving for gaming may make secondary rewards more salient than primary ones, thus promoting participation in addictive patterns of gaming.

Identifying neural signatures of tobacco retail outlet exposure: Preliminary validation of a "community neuroscience" paradigm

An extensive epidemiological literature indicates that increased exposure to tobacco retail outlets (TROs) places never smokers at greater risk for smoking uptake and current smokers at greater risk for increased consumption and smoking relapse. Yet research into the mechanisms underlying this effect has been limited. This preliminary study represents the first effort to examine the neurobiological consequences of exposure to personally relevant TROs among both smokers (n = 17) and nonsmokers (n = 17). Individuals carried a global positioning system (GPS) tracker for 2 weeks. Traces were used to identify TROs and control outlets that fell inside and outside their ideographically defined activity space. Participants underwent functional MRI (fMRI) scanning during which they were presented with images of these storefronts, along with similar store images from a different county and rated their familiarity with these stores. The main effect of activity space was additive with a Smoking status × Store type interaction, resulting in smokers exhibiting greater neural activation to TROs falling inside activity space within the parahippocampus, precuneus, medial prefrontal cortex, and dorsal anterior insula. A similar pattern was observed for familiarity ratings. Together, these preliminary findings suggest that the otherwise distinct neural systems involved in self-orientation/self-relevance and smoking motivation may act in concert and underlie TRO influence on smoking behavior. This study also offers a novel methodological framework for evaluating the influence of community features on neural activity that can be readily adapted to study other health behaviors.

Neurobiological correlates of cue-reactivity in alcohol-use disorders: A voxel-wise meta-analysis of fMRI studies

Altered brain responses to alcohol-associated stimuli are a neural hallmark of alcohol-use disorder (AUD) and a promising target for pharmacotherapy. However, findings in cue-reactivity based functional MRI (fMRI) studies are inconclusive. To investigate the neural substrates of cue-reactivity and their relevance to treatment outcomes, alcohol craving and relapse in AUD patients, we performed five meta-analyses using signed differential mapping software. Our meta-analysis revealed that alcohol cues evoke greater cue-reactivity than neutral cues in the mesocorticolimbic circuit and lower reactivity in the parietal and temporal regions in AUD patients. Compared to controls, AUD individuals displayed hyperactivations in the medial prefrontal cortex and anterior/middle part of the cingulate cortex. After receiving AUD treatment, AUD patients exhibited greater activations in the precentral gyrus but reduced activations in the bilateral caudate nucleus, insula, right DLPFC, and left superior frontal gyrus. No significant results were found in cue-reactivity correlates of alcohol craving and relapse. Our results implicate cue-induced abnormalities in corticostriatal-limbic circuits may underline the pathophysiology of AUD, and have translational value for treatment development.

Altered patterns of fractional amplitude of low-frequency fluctuation and regional homogeneity in abstinent methamphetamine-dependent users

Methamphetamine (MA) could induce functional and structural brain alterations in dependent subjects. However, few studies have investigated resting-state activity in methamphetamine-dependent subjects (MADs). We aimed to investigate alterations of brain activity during resting-state in MADs using fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo). We analyzed fALFF and ReHo between MADs (n = 70) and healthy controls (HCs) (n = 84) and performed regression analysis using MA use variables. Compared to HCs, abstinent MADs showed increased fALFF and ReHo values in the bilateral striatum, decreased fALFF in the left inferior frontal gyrus, and decreased ReHo in the bilateral anterior cingulate cortex, sensorimotor cortex, and left precuneus. We also observed the fALFF values of bilateral striatum were positively correlated with the age of first MA use, and negatively correlated with the duration of MA use. The fALFF value of right striatum was also positively correlated with the duration of abstinence. The alterations of spontaneous cerebral activity in abstinent MADs may help us probe into the neurological pathophysiology underlying MA-related dysfunction and recovery. Since MADs with higher fALFF in the right striatum had shorter MA use and longer abstinence, the increased fALFF in the right striatum might implicate early recovery during abstinence.

The influence of homeostatic mechanisms on neural regulation of food craving in anorexia nervosa

BACKGROUND

Restrictive food intake in anorexia nervosa (AN) has been related to an overactive cognitive control network inhibiting intuitive motivational responses to food stimuli. However, the influence of short-term homeostatic signaling on the neural regulation of cue-induced food craving in AN is still unclear.

METHODS

Twenty-five women with AN and 25 matched normal-weight women were examined on two occasions after receiving either glucose or water directly into their stomach using a nasogastric tube. Participants were blinded to the type of infusion. An event-related functional magnetic resonance imaging paradigm was used to investigate the effect of intestinal glucose load on neural processing during either simple viewing or distraction from food stimuli.

RESULTS

Neural differences between patients with AN and normal-weight participants were found during the distraction from food stimuli, but not during the viewing condition. When compared to controls, patients with AN displayed increased activation during food distraction in the left parietal lobule/precuneus and fusiform gyrus after water infusion and decreased activation in ventromedial prefrontal and cingulate regions after intestinal glucose load.

CONCLUSIONS

Independent of the cephalic phase and the awareness of caloric intake, homeostatic influences trigger disorder-specific reactions in AN. Food distraction in patients with AN is associated with either excessive higher-order cognitive control during physiological hunger or decreased internally directed attention after intestinal glucose load. These findings suggest that food distraction plays an important role in the psychopathology of AN. This study was registered on clinicaltrials.gov with identifier: NCT03075371.

Sensory cue reactivity: Sensitization in alcohol use disorder and obesity

Neuroimaging techniques to measure the function of the human brain such as electroencephalography (EEG), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI), are powerful tools for understanding the underlying neural circuitry associated with alcohol use disorder (AUD) and obesity. The sensory (visual, taste and smell) paradigms used in neuroimaging studies represent an ideal platform to investigate the connection between the different neural circuits subserving the reward/executive control systems in these disorders, which may offer a translational mechanism for novel intervention predictions. Thus, the current review provides an integrated summary of the recent neuroimaging studies that have applied cue-reactivity paradigms and neuromodulation strategies to explore underlying alterations in neural circuitry as well in treatment strategies in AUD and obesity. Finally, we discuss literature on mechanisms associated with increased alcohol sensitivity post-bariatric surgery (BS) which offers guidance for future research to use sensory percepts in elucidating the relation of reward signaling in AUD development post-BS.

How the harm of drugs and their availability affect brain reactions to drug cues: a meta-analysis of 64 neuroimaging activation studies

Visual drug cues are powerful triggers of craving in drug abusers contributing to enduring addiction. According to previous qualitative reviews, the response of the orbitofrontal cortex to such cues is sensitive to whether subjects are seeking treatment. Here we re-evaluate this proposal and assessed whether the nature of the drug matters. To this end, we performed a quantitative meta-analysis of 64 neuroimaging studies on drug-cue reactivity across legal (nicotine, alcohol) or illegal substances (cocaine, heroin). We used the ALE algorithm and a hierarchical clustering analysis followed by a cluster composition statistical analysis to assess the association of brain clusters with the nature of the substance, treatment status, and their interaction. Visual drug cues activate the mesocorticolimbic system and more so in abusers of illegal substances, suggesting that the illegal substances considered induce a deeper sensitization of the reward circuitry. Treatment status had a different modulatory role for legal and illegal substance abusers in anterior cingulate and orbitofrontal areas involved in inter-temporal decision making. The class of the substance and the treatment status are crucial and interacting factors that modulate the neural reactivity to drug cues. The orbitofrontal cortex is not sensitive to the treatment status per se, rather to the interaction of these factors. We discuss that these varying effects might be mediated by internal predispositions such as the intention to quit from drugs and external contingencies such as the daily life environmental availability of the drugs, the ease of getting them and the time frame of potential reward through drug consumption.

Cue-Reactivity Among Young Adults With Problematic Instagram Use in Response to Instagram-Themed Risky Behavior Cues: A Pilot fMRI Study

Background

Problematic Instagram use (PIGU), a specific type of internet addiction, is prevalent among adolescents and young adults. In certain instances, Instagram acts as a platform for exhibiting photos of risk-taking behavior that the subjects with PIGU upload to gain likes as a surrogate for gaining peer acceptance and popularity.

Aims

The primary objective was to evaluate whether addiction-specific cues compared with neutral cues, i.e., negative emotional valence cues vs. positive emotional valence cues, would elicit activation of the dopaminergic reward network (i.e., precuneus, nucleus accumbens, and amygdala) and consecutive deactivation of the executive control network [i.e., medial prefrontal cortex (mPFC) and dorsolateral prefrontal cortex (dlPFC)], in the PIGU subjects.

Method

An fMRI cue-induced reactivity study was performed using negative emotional valence, positive emotional valence, and truly neutral cues, using Instagram themes. Thirty subjects were divided into PIGU and healthy control (HC) groups, based on a set of diagnostic criteria using behavioral tests, including the Modified Instagram Addiction Test (IGAT), to assess the severity of PIGU. In-scanner recordings of the subjects’ responses to the images and regional activity of the neural addiction pathways were recorded.

Results

Negative emotional valence > positive emotional valence cues elicited increased activations in the precuneus in the PIGU group. A negative and moderate correlation was observed between PSC at the right mPFC with the IGAT scores of the PIGU subjects when corrected for multiple comparisons [r = −0.777, (p < 0.004, two-tailed)].

Conclusion

Addiction-specific Instagram-themed cues identify the neurobiological underpinnings of Instagram addiction. Activations of the dopaminergic reward system and deactivation of the executive control network indicate converging neuropathological pathways between Instagram addiction and other types of addictions.

More restriction, more overeating: conflict monitoring ability is impaired by food-thought suppression among restrained eaters

Numerous studies have shown that restrained eating is not an effective weight loss strategy. Restrained eaters often suppress their desires and thoughts about tasty food, which makes it more difficult to control themselves in subsequent eating behavior. The ego depletion impairs conflict monitoring abilities. Therefore, this study explored the effects of food thoughts suppression on restrained eaters' conflict monitoring. Therefore, this study used functional magnetic resonance imaging (fMRI) methods to explore changes in the activity of brain regions involved in conflict monitoring when restrained eaters choose between high- and low-calorie foods after either suppressing or not suppressing thoughts about food. The results showed that, compared to the control condition, after suppression of such thoughts, restrained eaters chose more high-calorie foods and displayed decreased activity in the dorsal anterior cingulate cortex-an important region in charge of conflict monitoring. At the same time, the functional coupling of the dorsal anterior cingulate cortex and the precuneus increased. Our findings suggest that restrained eaters' suppression of thoughts about tasty food could lead to a decline in their ability to monitor conflicts between current behaviors and goals, which in turn leads to unhealthy eating behavior.

Drug-Induced Craving for Methamphetamine Is Associated With Neural Methamphetamine Cue Reactivity

OBJECTIVE

Drug craving serves as the major motivator to propagate drug use and is thought to elicit relapse in abstinent individuals. Although craving for methamphetamine has been investigated using both laboratory and neuroimaging methodologies, the relationship between drug-induced craving and neural responses to methamphetamine cues has yet to be explored. Therefore, the present study investigated whether methamphetamine-induced craving responses in the laboratory were associated with neural response to methamphetamine cues.

METHOD

Non-treatment-seeking individuals with methamphetamine use disorder (n = 15) completed two sessions, one in the laboratory where they underwent a methamphetamine infusion, and one in the magnetic resonance imaging scanner where they viewed methamphetamine cues. Participants reported their craving for methamphetamine over the course of the laboratory session. Analyses examined the association between peak ratings of methamphetamine-induced craving and neural activation to methamphetamine cues.

RESULTS

In individuals with a methamphetamine use disorder, methamphetamine-induced craving was positively associated with neural methamphetamine cue reactivity in the precuneus, putamen, and ventromedial prefrontal cortex (Z > 2.3, p < .05).

CONCLUSIONS

There is a shared neurobiology underlying cue- and drug-induced craving in individuals with methamphetamine use disorder. Treatments that disrupt this circuitry may decrease craving and help prevent relapse.

Addiction severity modulates the precuneus involvement in internet gaming disorder: Functionality, morphology and effective connectivity

Although higher precuneus activation has often been observed in subjects with addictions when facing addiction-relevant cues, the recruitment of the precuneus is not consistent across studies. Here, we examined the extent to which addiction severity may relate to precuneus involvement during cue reactivity in internet gaming disorder (IGD). We recruited 65 subjects with IGD, collected brain responses when exposed to gaming cues and assessed brain structure. We correlated IGD severity with brain responses during a cue-craving task, precuneus volume, and connectivity with respect to inputs/outputs to/from the precuneus. In the cue-craving task, IGD severity was positively correlated with precuneus activation when exposed to gaming cues. IGD severity was also positively correlated with the volume of precuneus and connectivity from the hippocampal gyrus to the precuneus. IGD severity was also negatively correlated with connectivity from the middle frontal gyrus to the precuneus. In IGD, IGD severity relates to precuneus involvement with respect to functionality, morphology, and connectivity. The precuneus may act as a platform for integrating potential contradictory information between executive control and sub-cortical cravings.

Verbal suggestions of nicotine content modulate ventral tegmental neural activity during the presentation of a nicotine-free odor in cigarette smokers

Expectancies of nicotine content have been shown to impact smokers' subjective responses and smoking behaviors. However, little is known about the neural substrates modulated by verbally induced expectancies in smokers. In this study we used functional magnetic resonance imaging (fMRI) to investigate how verbally induced expectations, regarding the presence or absence of nicotine, modulated smokers' neural response to a nicotine-free odor. While laying in the scanner, all participants (N = 24) were given a nicotine-free odor, but whereas one group was correctly informed about the absence of nicotine (control group n = 12), the other group was led to believe that the presented odor contained nicotine (expectancy group n = 12). Smokers in the expectancy group had significantly increased blood-oxygen-level-dependent (BOLD) responses during the presentation of the nicotine-free odor in the left ventral tegmental area (VTA), and in the right insula, as compared to smokers in the control group (Regions of interest analysis with pFWE-corrected p ≤ 0.05). At a more liberal uncorrected statistical level (p-unc ≤ 0.001), increased bilateral reactivity in the dorsolateral prefrontal cortex (dlPFC) was also observed in the expectancy group as compared with the control group. Our findings suggest that nicotine-expectancies induced through verbal instructions can modulate nicotine relevant brain regions, without nicotine administration, and provide further neural support for the key role that cognitive expectancies play in the cause and treatment of nicotine dependence.

Neuroimaging findings from an experimental pharmacology trial of naltrexone in heavy drinkers of East Asian descent

BACKGROUND

Despite known genetic variation across races, studies examining pharmacogenetics of a single nucleotide polymorphism (SNP) of the mu-opioid receptor gene (OPRM1) on clinical response to naltrexone have been conducted in predominantly Caucasian samples. Evidence is mixed for pharmacogenetic OPRM1 and naltrexone effects on neural responses to alcohol cues. The current study tests the pharmacogenetic effects of naltrexone and OPRM1 on neural responses to alcohol taste cues in heavy drinkers of East Asian descent.

METHODS

Participants (N = 41) completed two double-blinded and counterbalanced functional magnetic resonance imaging (fMRI) sessions: one after taking naltrexone (50 mg/day) for four days and one after taking placebo for four days. Following titration, participants completed an fMRI alcohol taste-cues task. Analyses tested effects of naltrexone, OPRM1, and their interaction in whole-brain and region of interest (ROI) analyses of functional activation and functional connectivity in response to alcohol versus water taste cues.

RESULTS

We found no effects of naltrexone orOPRM1 on neural activation in whole-brain and ROI analyses, which included left and right ventral striatum (VS), anterior cingulate cortex (ACC), and orbitofrontal cortex (OFC). Naltrexone increased functional connectivity between left VS and clusters in medial prefrontal cortex, posterior cingulate gyrus, as well as right VS and occipital cortex, compared to placebo.

CONCLUSIONS

Naltrexone treatment enhanced functional connectivity in a key reinforcement-related pathway during alcohol versus water taste cues, corroborating neuroimaging work with other substances. Null medication and pharmacogenetics effects on functional activation add to a mixed naltrexone literature and may underscore the modest size of these effects in East Asians.

Drug-Induced Craving for Methamphetamine Is Associated With Neural Methamphetamine Cue Reactivity

OBJECTIVE

Drug craving serves as the major motivator to propagate drug use and is thought to elicit relapse in abstinent individuals. Although craving for methamphetamine has been investigated using both laboratory and neuroimaging methodologies, the relationship between drug-induced craving and neural responses to methamphetamine cues has yet to be explored. Therefore, the present study investigated whether methamphetamine-induced craving responses in the laboratory were associated with neural response to methamphetamine cues.

METHOD

Non-treatment-seeking individuals with methamphetamine use disorder (n = 15) completed two sessions, one in the laboratory where they underwent a methamphetamine infusion, and one in the magnetic resonance imaging scanner where they viewed methamphetamine cues. Participants reported their craving for methamphetamine over the course of the laboratory session. Analyses examined the association between peak ratings of methamphetamine-induced craving and neural activation to methamphetamine cues.

RESULTS

In individuals with a methamphetamine use disorder, methamphetamine-induced craving was positively associated with neural methamphetamine cue reactivity in the precuneus, putamen, and ventromedial prefrontal cortex (Z > 2.3, p < .05).

CONCLUSIONS

There is a shared neurobiology underlying cue- and drug-induced craving in individuals with methamphetamine use disorder. Treatments that disrupt this circuitry may decrease craving and help prevent relapse.

Prospective changes in neural alcohol cue reactivity in at-risk adolescents

Adolescence represents an ideal time for elucidating the etiology of cue reactivity profiles. This study examined the influence of three risk factors consistently associated with heavy adolescent drinking on alcohol cue reactivity. Youth were first assessed while still naïve to alcohol (12-14 years old) and followed after transitioning into alcohol use (17-21 years old). The effects of family history of substance use disorder, sex, and history of early of dating (i.e., before 14 years of age) on BOLD response contrast to alcohol picture cues were examined in a linear mixed model, controlling for age and alcohol use patterns at follow-up. Activation to alcohol picture cues differed as a function of risk factor and time. At baseline, family history positive youth showed greater activation to alcohol cues than family history negative peers in the right middle occipital and anterior cingulate gyri. Youth with a history of early-dating showed greater activation to alcohol cues, compared to non-early daters, in the left anterior cingulate/white matter region. Girls showed greater activation to alcohol than boys at baseline in left middle frontal gyrus. At follow-up, after drinking started, patterns reversed for each risk factor. These results indicate that even prior to initiating alcohol use, adolescents showed differences in activation to alcohol cues based on their family history, dating history, and sex.

Elucidating the Effect of a Brief Drinking Intervention Using Neuroimaging: A Preliminary Study

BACKGROUND

Brief interventions have empirical support for acutely reducing alcohol use among non-treatment-seeking heavy drinkers. Neuroimaging techniques allow for the examination of the neurobiological effect of behavioral interventions, probing brain systems putatively involved in clinical response to treatment. Few studies have prospectively evaluated whether psychosocial interventions attenuate neural cue reactivity that in turn reduces drinking in the same population. This study aimed to examine the effect of a brief intervention on drinking outcomes, neural alcohol cue reactivity, and the ability of neural alcohol cue reactivity to prospectively predict drinking outcomes.

METHODS

Non-treatment-seeking heavy drinking participants were randomized to receive a brief interview intervention (n = 22) or an attention-matched control (n = 24). Immediately following the intervention or control, participants underwent a functional magnetic resonance imaging scan comprised of the alcohol taste cues paradigm. Four weeks after the intervention (or control), participants completed a follow-up visit to report on their past-month drinking. Baseline and follow-up percent heavy drinking days (PHDD) were calculated for each participant.

RESULTS

There was no significant effect of the brief intervention on PHDD at follow-up or on modulating neural activation to alcohol relative to water taste cues. There was a significant association between neural response to alcohol taste cues and PHDD across groups (Z > 2.3, p < 0.05), such that individuals who had greater neural reactivity to alcohol taste cues in the precuneus and prefrontal cortex (PFC) had fewer PHDD at follow-up.

CONCLUSIONS

This study did not find an effect of the brief intervention on alcohol use in this sample, and the intervention was not associated with differential neural alcohol cue reactivity. Nevertheless, greater activation of the precuneus and PFC during alcohol cue exposure predicted less alcohol use prospectively suggesting that these neural substrates subserve the effects of alcohol cues on drinking behavior.

Increased Connectivity Between the Nucleus Accumbens and the Default Mode Network in Patients With Schizophrenia During Cigarette Cravings

Objective: Compared to the general population, tobacco smoking cessation rates are lower in populations with schizophrenia. Unfortunately, the potential neurophysiologic mechanisms underlying these low cessation rates in schizophrenia have been seldom studied using functional neuroimaging. Recently, it has been shown that tobacco cravings are increased in smokers with schizophrenia compared to smokers with no comorbid psychiatric disorder. Given the critical role of the brain reward system in the neurobiology of addiction, we sought to examine the functional connectivity of core regions of this system in smokers with schizophrenia during the viewing of appetitive smoking cues. Methods: Smokers with (n = 18) and without (n = 24) schizophrenia were scanned using functional magnetic resonance imaging while viewing appetitive cigarette images. Functional connectivity analyses were performed using the bilateral nucleus accumbens as the seed regions. Results: Smokers with schizophrenia and smokers with no psychiatric comorbidity did not differ in subjective cravings in response to appetitive smoking cues. However, in smokers with schizophrenia relative to control smokers, we found an increased connectivity between the nucleus accumbens and regions involved in the default mode network (e.g., middle temporal gyrus and precuneus), which are involved in self-referential processes. Moreover, a positive correlation was observed between the left nucleus accumbens and left middle temporal gyrus connectivity and cigarette cravings across both groups of smokers. Conclusions: These results highlight a key role of the nucleus accumbens in cigarette craving in schizophrenia and suggest that the subjective valuation of cigarette cues is increased in this population. Similar neurofunctional studies on cravings for other psychoactive substances in schizophrenia are warranted.

The top-down regulation from the prefrontal cortex to insula via hypnotic aversion suggestions reduces smoking craving

Hypnosis has been shown to have treatment effects on nicotine addiction. However, the neural basis of these effects is poorly understood. This preliminary study investigated the neural mechanisms of hypnosis-based treatment on cigarette smoking, specifically, whether the hypnosis involves a top-down or bottom-up mechanism. Two groups of 45 smokers underwent a smoking aversion suggestion and viewed smoking-related pictures and neutral pictures. One group underwent functional magnetic resonance imaging scanning twice (control and hypnotic states), whereas the other group underwent two electroencephalograph sessions. Our study found that self-reported smoking craving decreased in both groups following hypnosis. Smoking cue-elicited activations in the right dorsal lateral prefrontal cortex (rDLPFC) and left insula (lI) and the functional connectivity between the rDLPFC and lI were increased in the hypnotic state compared with the control state. The delta band source waveforms indicated the activation from 390 to 862 ms at the rDLPFC and from 490 to 900 ms at the lI was significantly different between the smoking and neutral conditions in the hypnotic state, suggesting the activation in the rDLPFC preceded that in the lI. These results suggest that the decreased smoking craving via hypnotic aversion suggestions may arise from the top-down regulation of the rDLPFC to the lI. Our findings provide novel neurobiological evidence for understanding the therapeutic effects of hypnosis on nicotine addiction, and the prefrontal-insula circuit may serve as an imaging biomarker to monitor the treatment efficacy noninvasively.

Brain Structure Alterations in Respect to Tobacco Consumption and Nicotine Dependence: A Comparative Voxel-Based Morphometry Study

The main purpose of this study is to examine the lifetime tobacco consumption and the degree of nicotine dependence related gray matter (GM) and white matter (WM) volume alterations in young adult-male smokers. Fifty-three long-term male smokers and 53 well-matched male healthy non-smokers participated in the study, and the smokers were respectively categorized into light and heavy tobacco consumption subgroups by pack-years and into moderate and severe nicotine dependence subgroups using the Fagerström Test for Nicotine Dependence (FTND). Voxel-based morphometry analysis was then performed, and ANCOVA analysis combined with subsequent post hoc test were used to explore the between-group brain volume abnormalities related to the smoking amount and nicotine dependence. Light and heavy smokers displayed smaller GM and WM volumes than non-smokers, while heavy smokers were found with more significant brain atrophy than light smokers in GM areas of precuneus, inferior and middle frontal gyrus, superior temporal gyrus, cerebellum anterior lobe and insula, and in WM areas of cerebellum anterior lobe. However, the contrary trend was observed regarding alterations associated with severity of nicotine dependence. Severe nicotine dependence smokers rather demonstrated less atrophy levels compared to moderate nicotine dependence smokers, especially in GM areas of precuneus, superior and middle temporal gyrus, middle occipital gyrus, posterior cingulate and insula, and in WM areas of precuneus, posterior cingulate, cerebellum anterior lobe and midbrain. The results reveal that the nicotine dependence displays a dissimilar effect on the brain volume in comparison to the cigarette consumption. Our study could provide new evidences to understand the adverse effects of smoking on the brain structure, which is helpful for further treatment of smokers.

Development, Initial Testing and Challenges of an Ecologically Valid Reward Prediction Error FMRI Task for Alcoholism

Aims

To advance translational studies of the role of reward prediction error (PE) in alcohol use disorder, the present study sought to develop and conduct an initial test of an alcohol-specific PE task paradigm using functional magnetic resonance imaging in humans.

Methods

Alcohol dependent or social drinkers received small tastes of their preferred alcohol beverage or control beverage, with preceding visual cues indicating whether alcohol (or water) would be delivered. To assess both positive and negative PE signals, expectancies were systematically violated in both positive (i.e. expecting water and receiving alcohol) and negative (i.e. expecting alcohol and receiving water) directions. Exploratory trial-by-trial analyses were conducted to explore temporal fluctuations of activation within a priori-defined regions of interest that have been implicated in cue reactivity and PE processing.

Results

Across the entire sample of participants, positive PE-related brain activation was found in a large cluster comprised of frontal lobe regions, as well as insular cortex, and motor/sensory cortices. Compared to social drinking subjects, alcohol dependent subjects had greater positive PE-related brain activity in left superior parietal lobule, lateral occipital cortex and postcentral gyrus. Exploratory trial-by-trial analyses indicated differences in activation specific to type of taste, mostly at earlier trials.

Conclusions

This task-development oriented pilot study found that PE signaling may not be detected in expected brain regions when image analyses average across all PE trials of the task. Rather, a trial-by-trial analysis approach may help detect sparse, temporally distinct PE signaling in expected reward processing regions.

Short Summary

This fMRI study of reward prediction error found greater positive prediction error-related activity (i.e. expecting water taste, receiving alcohol taste) in alcohol dependent individuals relative to social drinkers in parietal and occipital cortices. Trial-by-trial analyses may be able to better detect sparse prediction error signaling in expected reward processing regions.

Differences in White Matter Microstructure and Connectivity in Nontreatment-Seeking Individuals with Alcohol Use Disorder

BACKGROUND

Diffusion-weighted imaging (DWI) has been widely used to investigate the integrity of white matter (WM; indexed by fractional anisotropy [FA]) in alcohol dependence and cigarette smoking. These disorders are highly comorbid, yet cigarette use has often not been adequately controlled in neuroimaging studies of alcohol-dependent populations. In addition, information on WM deficits in currently drinking, nontreatment-seeking (NTS) individuals with alcohol dependence is limited. Therefore, the aim of this work was to investigate WM microstructural integrity in alcohol use disorder by comparing matched samples of cigarette smoking NTS and social drinkers (SD).

METHODS

Thirty-eight smoking NTS and 19 smoking SD subjects underwent DWI as well as structural magnetic resonance imaging. After an in-house preprocessing of the DWI data, FA images were analyzed with tract-based spatial statistics (TBSS). FA obtained from the TBSS skeleton was tested for correlation with recent alcohol consumption.

RESULTS

Smoking NTS had lower FA relative to smoking SD, predominantly in the left hemisphere (p < 0.05, family-wise error rate corrected across FA skeleton). Across the full sample, FA and number of drinks per week were negatively related (ρ = -0.348, p = 0.008). Qualitative analyses of the structural connections through compromised WM as identified by TBSS showed differential connectivity of gray matter in NTS compared to SD subjects of left frontal, temporal, and parietal regions.

CONCLUSIONS

NTS subjects had lower WM FA than SD, indicating compromised WM integrity in the NTS population. The inverse relationship of entire WM skeleton FA with self-reported alcohol consumption supports previous evidence of a continuum of detrimental effects of alcohol consumption on WM. These results provide additional evidence that alcohol dependence is associated with reduced WM integrity in currently drinking NTS alcohol-dependent individuals, after controlling for the key variable of cigarette smoking.

TLR4 Methylation Moderates the Relationship Between Alcohol Use Severity and Gray Matter Loss

OBJECTIVE

Alcohol use disorders (AUDs) are associated with decreased gray matter, and neuroinflammation is one mechanism through which alcohol may confer such damage, given that heavy alcohol use may promote neural damage via activation of toll-like receptor 4 (TLR4)-mediated inflammatory signaling cascades. We previously demonstrated that TLR4 is differentially methylated in AUD compared with control subjects, and the present study aims to extend this work by examining whether TLR4 methylation moderates the relationship between alcohol use and gray matter.

METHOD

We examined TLR4 methylation and gray matter thickness in a large sample (N = 707; 441 males) of adults (ages 18-56) reporting a range of AUD severity (mean Alcohol Use Disorders Identification Test score = 13.18; SD = 8.02). We used a series of ordinary least squares multiple regression equations to regress gray matter in four bilateral brain regions (precuneus, lateral orbitofrontal, inferior parietal, and superior temporal) on alcohol use, TLR4 methylation, and their interaction, controlling for demographic, psychological, and other substance use variables.

RESULTS

After we corrected for multiple tests, a significant Alcohol × TLR4 Methylation interaction emerged in the equations modeling left precuneus and right inferior parietal gray matter. Follow-up analyses examining the nature of these interactions demonstrated a significant negative association between alcohol and precuneus and inferior parietal gray matter in individuals with low TLR4 methylation, but no relationship between alcohol and gray matter in the high methylation group.

CONCLUSIONS

These findings suggest that TLR4 methylation may be protective against the damage conferred by alcohol on precuneus and inferior parietal gray matter, thereby implicating TLR4 for further investigation as a possible AUD treatment target.

Gray matter deficits and altered resting-state connectivity in the superior temporal gyrus among individuals with problematic hypersexual behavior

Neuroimaging studies on the characteristics of hypersexual disorder have been accumulating, yet alternations in brain structures and functional connectivity in individuals with problematic hypersexual behavior (PHB) has only recently been studied. This study aimed to investigate gray matter deficits and resting-state abnormalities in individuals with PHB using voxel-based morphometry and resting-state connectivity analysis. Seventeen individuals with PHB and 19 age-matched healthy controls participated in this study. Gray matter volume of the brain and resting-state connectivity were measured using 3T magnetic resonance imaging. Compared to healthy subjects, individuals with PHB had significant reductions in gray matter volume in the left superior temporal gyrus (STG) and right middle temporal gyrus. Individuals with PHB also exhibited a decrease in resting-state functional connectivity between the left STG and left precuneus and between the left STG and right caudate. The gray matter volume of the left STG and its resting-state functional connectivity with the right caudate both showed significant negative correlations with the severity of PHB. The findings suggest that structural deficits and resting-state functional impairments in the left STG might be linked to PHB and provide new insights into the underlying neural mechanisms of PHB.

Predictors of Naltrexone Response in a Randomized Trial: Reward-Related Brain Activation, OPRM1 Genotype, and Smoking Status

Naltrexone reduces drinking among individuals with alcohol use disorders (AUDs), but it is not effective for everyone. Variability in its effects on reward-related brain activation, genetic variation, and/or cigarette smoking may account for this mixed response profile. This randomized clinical trial tested the effects of naltrexone on drinking and alcohol cue-elicited brain activation, evaluated whether OPRM1 A118G genotype or smoking moderated these effects, and explored whether the effects of medication on cue-elicited activation predicted subsequent drinking. One hundred and fifty-two treatment-seeking individuals with alcohol dependence, half preselected to carry at least one A118G G (Asp) allele, were randomized to naltrexone (50 mg) or placebo for 16 weeks and administered an fMRI alcohol cue reactivity task at baseline and after 2 weeks of treatment. Naltrexone, relative to placebo, significantly reduced alcohol cue-elicited activation of the right ventral striatum (VS) between baseline and week 2 and reduced heavy drinking over 16 weeks. OPRM1 genotype did not significantly moderate these effects, but G-allele carriers who received naltrexone had an accelerated return to heavy drinking after medication was stopped. Smoking moderated the effects of medication on drinking, such that naltrexone was superior to placebo only among smokers. The degree of reduction in right VS activation between scans interacted with medication in predicting subsequent drinking, such that individuals with greater reduction in activation who received naltrexone, but not placebo, experienced the least heavy drinking during the following 14 weeks. These data replicate previous findings that naltrexone reduces heavy drinking and reward-related brain activation among treatment-seeking individuals with AUDs, and indicate that smoking and the magnitude of reduction in cue-elicited brain activation may predict treatment response.

Altered functional connectivity to stressful stimuli in prenatally cocaine-exposed adolescents

BACKGROUND

Prenatal cocaine exposure (PCE) is linked to addiction and obesity vulnerability. Neural responses to stressful and appetitive cues in adolescents with PCE versus those without have been differentially linked to substance-use initiation. However, no prior studies have assessed cue-reactivity responses among PCE adolescents using a connectivity-based approach.

METHODS

Twenty-two PCE and 22 non-prenatally drug-exposed (NDE) age-, sex-, IQ- and BMI-matched adolescents participated in individualized guided imagery with appetitive (favorite-food), stressful and neutral-relaxing cue scripts during functional magnetic resonance imaging. Subjective favorite-food craving scores were collected before and after script exposure. A data-driven voxel-wise intrinsic connectivity distribution analysis was used to identify between-group differences and examine relationships with craving scores.

RESULTS

A group-by-cue interaction effect identified a parietal lobe cluster where PCE versus NDE adolescents showed less connectivity during stressful and more connectivity during neutral-relaxing conditions. Follow-up seed-based connectivity analyses revealed that, among PCE adolescents, the parietal seed was positively connected to inferior parietal and sensory areas and negatively connected to corticolimbic during both stress and neutral-relaxing conditions. For NDE, greater parietal connectivity to parietal, cingulate and sensory areas and lesser parietal connectivity to medial prefrontal areas were found during stress compared to neutral-relaxing cueing. Craving scores inversely correlated with corticolimbic connectivity in PCE, but not NDE adolescents, during the favorite-food condition.

CONCLUSIONS

Findings from this first data-driven intrinsic connectivity analysis of PCE influences on adolescent brain function indicate differences relating to PCE status and craving. These findings provide insight into the developmental impact of in utero drug exposure.

Resting-State Functional Connectivity of the Basal Nucleus of Meynert in Cigarette Smokers: Dependence Level and Gender Differences

Introduction

Numerous studies have characterized impaired cerebral functioning in nicotine-addicted individuals. Whereas nicotine interacts with multiple neurotransmitters in cortical and subcortical circuits, it directly targets the cholinergic system, sourced primarily from the basal nucleus of Meynert (BNM). However, no studies have examined how this cholinergic system is influenced by cigarette smoking. Here, we addressed this gap of research.

Methods

Using a dataset from the Functional Connectome Projects, we investigated this issue by contrasting seed-based BNM connectivity of 40 current smokers and 170 age- and gender-matched nonsmokers. We followed our data analytic routines in recent work and examined differences between smokers and nonsmokers in men and women combined as well as separately.

Results

Compared to nonsmokers, female but not male smokers demonstrated greater positive BNM connectivity to the supplementary motor area, bilateral anterior insula, and right superior temporal/supramarginal gyri as well as greater negative connectivity to the posterior cingulate cortex and precuneus. Further, BNM connectivity to the supplementary motor area is negatively correlated to the Fagerström Test for Nicotine Dependence score in male but not female smokers.

Conclusions

Along with a previous report of upregulated nicotinic acetylcholine receptor in male but not female smokers, these new findings highlight functional changes of the cholinergic systems in cigarette smokers. The results suggest sex-specific differences in cholinergic dysregulation and a need for multiple imaging modalities to capture the neural markers of nicotine addiction.

Implications

Nicotine influences cognition via cholinergic projections of the basal forebrain to the cerebral cortex. This study examined changes in resting-state whole-brain functional connectivity of the BNM in cigarette smokers. The new findings elucidate for the first time sex differences in BNM-cerebral connectivity in cigarette smoking.

Delta coherence in resting-state EEG predicts the reduction in cigarette craving after hypnotic aversion suggestions

Cigarette craving is a key contributor of nicotine addiction. Hypnotic aversion suggestions have been used to help smoking cessation and reduce smoking relapse rates but its neural basis is poorly understood. This study investigated the underlying neural basis of hypnosis treatment for nicotine addiction with resting state Electroencephalograph (EEG) coherence as the measure. The sample consisted of 42 male smokers. Cigarette craving was measured by the Tobacco Craving Questionnaire. The 8-minute resting state EEG was recorded in baseline state and after hypnotic induction in the hypnotic state. Then a smoking disgust suggestion was performed. A significant increase in EEG coherence in delta and theta frequency, and significant decrease in alpha and beta frequency, between the baseline and the hypnotic state was found, which may reflect alterations in consciousness after hypnotic induction. More importantly, the delta coherence between the right frontal region and the left posterior region predicted cigarette craving reduction after hypnotic aversion suggestions. This suggests that the functional connectivity between these regions plays an important role in reducing cigarette cravings via hypnotic aversion suggestions. Thus, these brain regions may serve as an important target to treat nicotine addiction, such as stimulating these brain regions via repetitive transcranial magnetic stimulation.

The Effects of Pharmacological Opioid Blockade on Neural Measures of Drug Cue-Reactivity in Humans

Interactions between dopaminergic and opioidergic systems have been implicated in the reinforcing properties of drugs of abuse. The present study investigated the effects of opioid blockade, via naltrexone, on functional magnetic resonance imaging (fMRI) measures during methamphetamine cue-reactivity to elucidate the role of endogenous opioids in the neural systems underlying drug craving. To investigate this question, non-treatment seeking individuals with methamphetamine use disorder (N=23; 74% male, mean age=34.70 (SD=8.95)) were recruited for a randomized, placebo controlled, within-subject design and underwent a visual methamphetamine cue-reactivity task during two blood-oxygen-level dependent (BOLD) fMRI sessions following 3 days of naltrexone (50 mg) and matched time for placebo. fMRI analyses tested naltrexone-induced differences in BOLD activation and functional connectivity during cue processing. The results showed that naltrexone administration reduced cue-reactivity in sensorimotor regions and related to altered functional connectivity of dorsal striatum, ventral tegmental area, and precuneus with frontal, visual, sensory, and motor-related regions. Naltrexone also weakened the associations between subjective craving and precuneus functional connectivity with sensorimotor regions and strengthened the associations between subjective craving and dorsal striatum and precuneus connectivity with frontal regions. In conclusion, this study provides the first evidence that opioidergic blockade alters neural responses to drug cues in humans with methamphetamine addiction and suggests that naltrexone may be reducing drug cue salience by decreasing the involvement of sensorimotor regions and by engaging greater frontal regulation over salience attribution.

Dorsal anterior cingulate glutamate is associated with engagement of the default mode network during exposure to smoking cues

BACKGROUND

When exposed to smoking cues, nicotine dependent individuals activate brain regions overlapping with the default mode network (DMN), a network of regions involved in internally-focused cognition. The salience network (SN), which includes the dorsal anterior cingulate cortex (dACC), is thought to interact with the DMN and aids in directing attention toward salient internal or external stimuli. One possibility is that neurochemical variation in SN regions such as the dACC impact DMN reactivity to personally relevant stimuli such as smoking cues. This is consistent with emerging evidence suggesting an association between midline cortical glutamate (Glu) and activity in brain regions overlapping with the DMN.

METHODS

In 18 nicotine-dependent individuals, we assessed the relationship between DMN activation to smoking relative to neutral cues using functional magnetic resonance imaging and dACC Glu as measured by magnetic resonance spectroscopy. This association also was tested in a replication sample of 14 nicotine-dependent participants.

RESULTS

Not only was the DMN significantly less suppressed during smoking cue exposure, but also there was a positive association between DMN reactivity to smoking relative to neutral cues and dACC Glu (r=0.56, p<0.02). This finding was confirmed in the independent replication cohort (r=0.64, p<0.02).

CONCLUSIONS

The current findings confirm that the DMN is less suppressed when smokers view smoking relative to neutral cues, suggesting that smoking cues engage self-relevant processing. Furthermore, these results indicate that dACC Glu is associated with enhanced DMN engagement when nicotine-dependent individuals are exposed to self-relevant smoking cues.

Anticipatory reward processing among cocaine-dependent individuals with and without concurrent methadone-maintenance treatment: Relationship to treatment response

BACKGROUND

Cocaine dependence among opioid-dependent methadone-maintained individuals is a significant public health problem and is particularly challenging to treat. The neurobiology of this clinically complex population has not been previously assessed using fMRI.

METHODS

fMRI data from cocaine-dependent, methadone-maintained (CD-MM) patients (n=24), cocaine-dependent (CD) patients (n=20) and healthy comparison (HC) participants (n=21) were acquired during monetary incentive delay task performance. All patients were scanned prior to treatment for cocaine dependence. Between-group differences in anticipatory reward and loss processing were assessed using whole-brain ANOVAs in SPM12 (pFWE<0.05). Correlations between durations of abstinence during treatment and BOLD responses within the insula and caudate were also explored.

RESULTS

Main effects of diagnostic group, primarily involving decreased BOLD responses among CD-MM patients in comparison to HCs, were observed during anticipatory reward and loss processing within regions of posterior cingulate cortex, precuneus, inferior frontal gyrus and dorsolateral prefrontal cortex. BOLD responses within the right caudate were negatively associated with percentage of cocaine-negative urines during treatment among CD-MM patients, but not among non-methadone-maintained CD patients.

CONCLUSIONS

These data suggest neurofunctional differences that may be related to treatment outcomes for behavioral therapies between cocaine-dependent individuals with and without methadone-maintenance treatment. These findings may relate to differences in treatment efficacies and to the elevated relapse rates observed in methadone-maintained populations.

Increased ventro-medial prefrontal activations in schizophrenia smokers during cigarette cravings

BACKGROUND

Highly prevalent in schizophrenia, tobacco smoking substantially increases the risk of cardiac-related death. Compared to the general population, tobacco smoking cessation rates are lower in schizophrenia. Unfortunately, the reasons for these low cessation rates remain poorly understood. Recently, it has been shown that tobacco cravings are increased in schizophrenia smokers compared to smokers with no comorbid psychiatric disorder. In view of these results, we sought to examine - for the first time - the neurophysiologic responses elicited by cigarette cues in schizophrenia smokers. We hypothesized that cigarettes cues would elicit increased activations in brain regions involved in drug cravings in schizophrenia smokers relative to control smokers.

METHODS

Smokers with (n=18) and without (n=24) schizophrenia (DSM-IV criteria) were scanned using functional magnetic resonance imaging (fMRI) while viewing appetitive cigarette images.

RESULTS

Schizophrenia smokers and smokers with no psychiatric comorbidity did not differ in subjective cravings in response to appetitive smoking cues. However, in schizophrenia smokers relative to control smokers, we found that appetitive cigarette cues triggered increased activations of the bilateral ventro-medial prefrontal cortex, a core region of the brain reward system. Moreover, a negative correlation was observed between cigarette cravings and activations of the right ventro-medial prefrontal cortex in schizophrenia smokers.

DISCUSSION

The current results highlight a key role of the brain reward system in cigarette craving in schizophrenia, and suggest that the neurophysiologic mechanisms involved in the regulation of cue-induced cigarette craving are impaired in this population.

Conditioned place preferences in humans using secondary reinforcers

The goal of this experiment was to examine whether a conditioned place preference could be established in humans using a secondary reinforcer that provided little obvious reward to the participants. Two experiments were conducted to answer this question. In Experiment 1, 244 undergraduates were placed into a VR environment consisting of two visually distinct rooms connected by a door. Throughout the experiment, one room was randomly paired with occasional point rewards while the other unique room was never paired with rewards. Participants received thee pairings in each room. After a short break, a test session was administered, and participants were given free access to the entire VR environment and no point rewards were administered. On the test day, we observe that participants displayed a significant CPP for the room paired with points, as evidenced by significant differences in rating each of the rooms in terms of enjoyment. In Experiment 2, 77 undergraduates were tested using a biased conditioning approach in which an initial test session was conducted to obtain the participant's preferred room bias, and then the least-preferred room was designated as the points reward room for each participant. Using this biased conditioning approach, participants spent a significantly greater amount of time in the points-paired room. In this case, participants showed preferences based on explicit and implicit measures. These results suggest new approaches to examine the role of secondary reinforcers in nontraditional addictions such as internet, gaming, and gambling dependencies.

CREB-BDNF pathway influences alcohol cue-elicited activation in drinkers

Alcohol use disorder (AUD) is suggested to have polygenic risk factors and also exhibits neurological complications, strongly encouraging a translational study to explore the associations between aggregates of genetic variants and brain function alterations related to alcohol use. In this study, we used a semiblind multivariate approach, parallel independent component analysis with multiple references (pICA-MR) to investigate relationships of genome-wide single nucleotide polymorphisms with alcohol cue-elicited brain activations in 315 heavy drinkers, where pICA-MR assesses multiple reference genes for their architecture and functional influences on neurobiological conditions. The genetic component derived from the cAMP-response element-binding protein and -brain derived neurotrophic factor (CREB-BDNF) pathway reference was significantly associated (r = -0.38, P = 3.98 × 10(-12) ) with an imaging component reflecting hyperactivation in precuneus, superior parietal lobule, and posterior cingulate for drinkers with more severe alcohol dependence symptoms. The highlighted brain regions participate in many cognitive processes and have been robustly implicated in craving-related studies. The genetic factor highlighted the CREB and BDNF references, as well as other genes including GRM5, GRM7, GRID1, GRIN2A, PRKCA, and PRKCB. Ingenuity Pathway Analysis indicated that the genetic component was enriched in synaptic plasticity, GABA, and protein kinase A signaling. Collectively, our findings suggest that genetic variations in various neural plasticity and signaling pathways partially explain the variance of precuneus reactivity to alcohol cues which appears to be associated with AUD severity.