Association of Prefrontal-Striatal Functional Pathology With Alcohol Abstinence Days at Treatment Initiation and Heavy Drinking After Treatment Initiation

Neural Correlates of Stress and Alcohol Cue-Induced Alcohol Craving and of Future Heavy Drinking: Evidence of Sex Differences

OBJECTIVE

Stress and alcohol cue reactivity are associated with poor treatment outcomes in alcohol use disorder (AUD), but sex-specific neural correlates of stress and alcohol cue-induced craving compared with neutral cue-induced craving and of heavy drinking outcomes in AUD have not been examined. Thus, this study prospectively examined these associations and assessed sex differences.

METHODS

Treatment-seeking adults with AUD (N=77; 46 men and 31 women) completed a functional MRI task involving stress, alcohol, and neutral cue exposure with repeated assessments of alcohol craving. Most of these participants (N=72; 43 men and 29 women) then participated in an 8-week standardized behavioral AUD treatment program, during which the percentage of heavy drinking days was assessed.

RESULTS

Significant increases in both stress and alcohol cue-induced craving relative to neutral cue-induced craving were observed, with a greater alcohol-neutral contrast in craving relative to the stress-neutral contrast among men and equivalent stress-neutral and alcohol-neutral contrasts in craving among women. Whole-brain voxel-based regression analyses showed craving-associated hyperactivation in the neutral condition, but hypoactive prefrontal (ventromedial and lateral prefrontal, supplementary motor, and anterior cingulate regions) and striatal responses during exposure to stressful images (stress-neutral contrast) and alcohol cues (alcohol-neutral contrast), with significant sex differences. Additionally, a higher percentage of heavy drinking days was associated with hypoactivation of the subgenual anterior cingulate cortex and the bed nucleus of the stria terminalis in the stress-neutral contrast among women, hyperactivation of the hypothalamus in the stress-neutral contrast among men, and hyperactivation of the hippocampus in the alcohol-neutral contrast among men.

CONCLUSIONS

Sex differences in stress- and alcohol cue-induced responses in the cortico-striatal-limbic network related to subjective alcohol craving and to heavy drinking indicated that distinct brain circuits underlie alcohol use outcomes in women and men. These findings underscore the need for sex-specific therapeutics to address this neural dysfunction effectively.

Neurocognitive and neurobehavioral mechanisms of change following psychological treatment for alcohol use disorder

BACKGROUND

Although modestly effective treatments exist for alcohol use disorder (AUD), many individuals return to heavy drinking after treatment, suggesting the need for better understanding of factors that contribute to maintaining abstinence or drinking reductions. Whereas past studies identified what treatments work for AUD, recent studies focus more on why particular treatments work, and the mechanisms by which treatment leads to change. This focus on mechanisms of behavior change (MOBC) may inform the process by which treatment leads to better outcomes, and also may lead to new treatments or modifications of existing treatments that target empirically supported mechanisms known to lead to change. There is a paucity of studies examining MOBC from a neurocognitive perspective.

METHOD

To address this gap in knowledge, the study described here is examining emotional reactivity, alcohol cue reactivity, and cognitive control as potential MOBC at three levels of analysis - self-report, behavior, and neural.

RESULTS

One hundred ten treatment-seeking individuals with an AUD are being randomized to receive 8 sessions of either Cognitive Behavioral Treatment (CBT) or Mindfulness Based Treatment (MBT) after up to 4 sessions of a platform treatment focused on enhancing motivation to change. To establish the temporal relationship between changes in drinking and changes in MOBC, patients are assessed at baseline, during and immediately after treatment, and 9- and 15-months post-baseline. Relationships between changes in drinking and changes in the proposed MOBC will be examined using advanced mixed modeling techniques.

CONCLUSIONS

Results should advance AUD treatment by targeting treatments to neurocognitive MOBC.

Psilocybin-induced changes in neural reactivity to alcohol and emotional cues in patients with alcohol use disorder: an fMRI pilot study

This pilot study investigated psilocybin-induced changes in neural reactivity to alcohol and emotional cues in patients with alcohol use disorder (AUD). Participants were recruited from a phase II, randomized, double-blind, placebo-controlled clinical trial investigating psilocybin-assisted therapy (PAT) for the treatment of AUD (NCT02061293). Eleven adult patients completed task-based blood oxygen dependent functional magnetic resonance imaging (fMRI) approximately 3 days before and 2 days after receiving 25 mg of psilocybin (n = 5) or 50 mg of diphenhydramine (n = 6). Visual alcohol and emotionally valanced (positive, negative, or neutral) stimuli were presented in block design. Across both alcohol and emotional cues, psilocybin increased activity in the medial and lateral prefrontal cortex (PFC) and left caudate, and decreased activity in the insular, motor, temporal, parietal, and occipital cortices, and cerebellum. Unique to negative cues, psilocybin increased supramarginal gyrus activity; unique to positive cues, psilocybin increased right hippocampus activity and decreased left hippocampus activity. Greater PFC and caudate engagement and concomitant insula, motor, and cerebellar disengagement suggests enhanced goal-directed action, improved emotional regulation, and diminished craving. The robust changes in brain activity observed in this pilot study warrant larger neuroimaging studies to elucidate neural mechanisms of PAT.Trial registration: NCT02061293.

People who binge drink show neuroendocrine tolerance to alcohol cues that is associated with immediate and future drinking- results from a randomized clinical experiment

Neuroendocrine tolerance to alcohol, i.e., a blunted cortisol response to alcohol, has been linked to Ventromedial Prefrontal Cortex (VmPFC) alcohol cue reactivity and relapse risk in severe Alcohol Use Disorders (AUDs), but its role in the development of AUDs is not clear. Recent work suggests that blunted cortisol responses to alcohol cues in individuals who engage in binge drinking (BD) may play a role in motivation to consume larger amounts of alcohol, but the link between this dysregulated endocrine response and BD's neural responses to alcohol cues remains unclear. To examine this, two groups of participants were recruited based on their recent drinking history. Thirty-three BD and 31 non-binging, social drinkers (SD) were exposed to alcohol cues and water cues in two separate 7 T functional magnetic resonance imaging (fMRI) scans. Each scan was followed by the Alcohol Taste Test (ATT) of implicit motivation for alcohol and a post-experiment, one-month prospective measurement of their "real world" drinking behavior. During each scan session, blood plasma was collected repeatedly to examine the separate effects of alcohol cues and alcohol consumption on cortisol levels. Relative to water cues and SD, BD demonstrated blunted cortisol cue reactivity that was negatively associated with VmPFC cue reactivity. In BD, both blunted cortisol and greater VmPFC cue reactivity were related to immediate and future alcohol consumption in the month following the scans. Thus, neuroendocrine tolerance in BD may be associated with increased incentive salience of cues and contribute mechanistically to increased alcohol consumption seen in the development of AUDs.

Laboratory and Real-World Experimental Approaches to Understanding Alcohol Relapse

Alcohol use disorder is highly prevalent and high risk of relapse remains a significant treatment challenge. Therefore, the utility of human laboratory models of relapse to further the understanding of psychobiological mechanisms that precipitate relapse risk and allow testing of novel interventions could be of benefit in expediting the development of effective treatments to target high relapse risk. Stress is a risk factor for the development of AUD and for relapse, and furthermore, chronic alcohol use leads to adaptations in central and peripheral stress biology. Here, we review our efforts to assess the integrity of these stress pathways in individuals with alcohol use disorder and whether adaptations in these systems play a role in relapse risk. Using validated human laboratory procedures to model two of the most common situations that contribute to relapse risk, namely stress and alcohol cues, we review how such models in the laboratory can predict subsequent relapse, and how we can measure specific identified biobehavioral markers of relapse effectively and ecologically in the real world. Finally, we discuss the significant implications of these findings for the development of novel and effective interventions that target stress dysregulation and craving as risk factors to treatment.

Acute alcohol and chronic drinking bidirectionally regulate the excitability of prefrontal cortex vasoactive intestinal peptide interneurons

The prefrontal cortex (PFC) regulates drinking behaviors and affective changes following chronic alcohol use. PFC activity is dynamically modulated by local inhibitory interneurons (INs), which can be divided into non-overlapping groups with distinct functional roles. Within deeper layers of neocortex, INs that express either parvalbumin or somatostatin directly inhibit pyramidal cells. By contrast, the plurality of all remaining INs express vasoactive intestinal peptide (VIP), reside within superficial layers, and preferentially target other types of INs. While recent studies have described adaptations to PFC parvalbumin-INs and somatostatin-INs in alcohol use models, whether ethanol or drinking affect the physiology of PFC VIP-INs has not been reported. To address this gap, we used genetically engineered female and male mice to target VIP-INs in layers 1-3 of prelimbic PFC for whole-cell patch-clamp electrophysiology. We found that ethanol (20 mM, ∼0.09 BEC/90 mg/dL) application to PFC brain slices enhances VIP-IN excitability. We next examined effects following chronic drinking by providing mice with 4 weeks of intermittent access (IA) ethanol two-bottle choice in the home cage. In these studies, VIP-INs from female and male IA ethanol mice displayed reduced excitability relative to cells from water-only controls. Finally, we assessed whether these effects continue into abstinence. After 7-13 days without ethanol, the hypo-excitability of VIP-INs from male IA ethanol mice persisted, whereas cells from female IA ethanol mice were not different from their controls. Together, these findings illustrate that acute ethanol enhances VIP-IN excitability and suggest these cells undergo pronounced homeostatic changes following long-term drinking.

Network state dynamics underpin craving in a transdiagnostic population

Emerging fMRI brain dynamic methods present a unique opportunity to capture how brain region interactions across time give rise to evolving affective and motivational states. As the unfolding experience and regulation of affective states affect psychopathology and well-being, it is important to elucidate their underlying time-varying brain responses. Here, we developed a novel framework to identify network states specific to an affective state of interest and examine how their instantaneous engagement contributed to its experience. This framework investigated network state dynamics underlying craving, a clinically meaningful and changeable state. In a transdiagnostic sample of healthy controls and individuals diagnosed with or at risk for craving-related disorders (N=252), we utilized connectome-based predictive modeling (CPM) to identify craving-predictive edges. An edge-centric timeseries approach was leveraged to quantify the instantaneous engagement of the craving-positive and craving-negative networks during independent scan runs. Individuals with higher craving persisted longer in a craving-positive network state while dwelling less in a craving-negative network state. We replicated the latter results externally in an independent group of healthy controls and individuals with alcohol use disorder exposed to different stimuli during the scan (N=173). The associations between craving and network state dynamics can still be consistently observed even when craving-predictive edges were instead identified in the replication dataset. These robust findings suggest that variations in craving-specific network state recruitment underpin individual differences in craving. Our framework additionally presents a new avenue to explore how the moment-to-moment engagement of behaviorally meaningful network states supports our changing affective experiences.

Testing pharmacotherapies for alcohol use disorder with cue exposure paradigms: A systematic review and quantitative synthesis of human laboratory trial methodology

Alcohol cue exposure is a widely used experimental paradigm for screening pharmacotherapies for alcohol use disorder (AUD). Medication-related reductions in cue-reactivity signal early efficacy and inform medications development. Yet, across trials, the design of cue exposure, parameter testing, and outcome reporting is heterogeneous. This systematic review is a quantitative synthesis of trial methodologies and effect size estimation for AUD medication-related craving and psychophysiological outcomes under the cue exposure paradigm. A PubMed search was conducted on January 3, 2022 based on identified pharmacotherapies for peer-reviewed articles reported in English. Study-level characteristics, including sample descriptors, paradigm design, analytic approach, and Cochrane Risk of Bias, along with descriptive statistics for cue-exposure outcomes, were coded by two independent raters. Study-level effect sizes were estimated for craving and psychophysiological outcomes separately and sample-level effect sizes were calculated for each medication. Thirty-six trials, comprising 1640 participants and testing 19 different medications satisfied eligibility criteria. All studies reported on biological sex (71% male participants on average). The exposure paradigms implemented used in vivo (n = 26), visual (n = 8), and audio script (n = 2) cues. Some trials included means for craving by medication condition in text (k = 7) or figures (k = 18). The quantitative synthesis included 63 effect sizes (craving kes  = 47; psychophysiological kes  = 16) from 28 unique randomized trials testing 15 medications for effects on cue reactivity. For cue-induced craving, eight medications (kes range: 1-12) demonstrated small-to-medium effects (Cohen's d range: |0.24-0.64|) compared to placebo, with individuals randomized to receive medication reporting lower craving following cue exposure. Recommendations are provided to promote further consilience, so that the utility of cue exposure paradigms can be maximized in the development of effective AUD pharmacotherapies. Future work should explore the predictive utility of medication-related reductions in cue-reactivity on clinical outcomes.

IL-6, but not TNF-α, response to alcohol cues and acute consumption associated with neural cue reactivity, craving, and future drinking in binge drinkers

Objective and design

Preclinical studies suggest learned immune system responses to alcohol cues and consumption may contribute to alcohol's pharmacodynamic properties and/or Alcohol Use Disorder (AUD) pathogenesis. Mechanistically, these immune alterations may be associated with increased craving and alcohol consumption, both acutely and over time. We sought to characterize this relationship in a randomized, counter-balanced, crossover neuroimaging experiment which took place between June 2020-November 2021.

Methods

Thirty-three binge drinkers (BD) and 31 non-binge, social drinkers (SD), matched for demographic and psychological variables, were exposed to alcohol cues and water cues in two separate 7 T functional magnetic resonance imaging (fMRI) scans. Each scan was followed by the Alcohol Taste Test (ATT) of implicit motivation for acute alcohol. Craving measures and blood cytokine levels were collected repeatedly during and after scanning to examine the effects of alcohol cues and alcohol consumption on craving levels, Tumor necrosis factor alpha (TNF-α), and Interleukin 6 (IL-6) levels. A post-experiment one-month prospective measurement of participants' "real world" drinking behavior was performed to approximate chronic effects.

Results

BD demonstrated significantly higher peak craving and IL-6 levels than SD in response to alcohol cues and relative to water cues. Ventromedial Prefrontal Cortex (VmPFC) signal change in the alcohol-water contrast positively related to alcohol cue condition craving and IL-6 levels, relative to water cue condition craving and IL-6 levels, in BD only. Additionally, peak craving and IL-6 levels were each independently related to ATT alcohol consumption and the number of drinks consumed in the next month for BD, again after controlling for craving and IL-6 repones to water cues. However, TNF-α release in the alcohol cue condition was not related to craving, neural activation, IL-6 levels, immediate and future alcohol consumption in either group after controlling for water cue condition responses.

Conclusions

In sum, BD show greater craving and IL-6 release in the alcohol cue condition than SD, both of which were associated with prefrontal cue reactivity, immediate alcohol consumption, and future alcohol consumption over the subsequent 30 days. Alcohol associated immune changes and craving effects on drinking behavior may be independent of one another or may be indicative of a common pathway by which immune changes in BD could influence motivation to consume alcohol.

Trial registration

Clinical Trials NCT04412824.

Binge drinking is associated with higher cortisol and lower hippocampal and prefrontal gray matter volume: Prospective association with future alcohol intake

Background

Cortisol is a significant driver of the biological stress response that is potently activated by acute alcohol intake and increased with binge drinking. Binge drinking is associated with negative social and health consequences and risk of developing alcohol use disorder (AUD). Both cortisol levels and AUD are also associated with changes in hippocampal and prefrontal regions. However, no previous research has assessed structural gray matter volume (GMV) and cortisol concurrently to examine BD effects on hippocampal and prefrontal GMV and cortisol, and their prospective relationship to future alcohol intake.

Methods

Individuals who reported binge drinking (BD: N = 55) and demographically matched non-binge moderate drinkers (MD: N = 58) were enrolled and scanned using high-resolution structural MRI. Whole brain voxel-based morphometry was used to quantify regional GMV. In a second phase, 65% of the sample volunteered to participate in prospective daily assessment of alcohol intake for 30 days post-scanning.

Results

Relative to MD, BD showed significantly higher cortisol and smaller GMV in regions including hippocampus, dorsal lateral prefrontal cortex (dlPFC), prefrontal and supplementary motor, primary sensory and posterior parietal cortex (FWE, p < 0.05). GMV in bilateral dlPFC and motor cortices were negatively associated with cortisol levels, and smaller GMV in multiple PFC regions was associated with more subsequent drinking days in BD.

Conclusion

These findings indicate neuroendocrine and structural dysregulation associated with BD relative to MD. Notably, BD-associated lower GMV regions were those involved in stress, memory and cognitive control, with lower GMV in cognitive control and motor regions also predicting higher levels of future alcohol intake in BD.

Chronic pain, chronic stress and substance use: overlapping mechanisms and implications

Chronic pain is among the most common reasons adults in the U.S. seek medical care. Despite chronic pain's substantial impact on individuals' physical, emotional, and financial wellness, the biologic underpinnings of chronic pain remain incompletely understood. Such deleterious impact on an individuals' wellness is also manifested in the substantial co-occurrence of chronic stress with chronic pain. However, whether chronic stress and adversity and related alcohol and substance misuse increases risk of developing chronic pain, and, if so, what the overlapping psychobiological processes are, is not well understood. Individuals suffering with chronic pain find alleviation through prescription opioids as well as non-prescribed cannabis, alcohol, and other drugs to control pain, and use of these substances have grown significantly. Substance misuse also increases experience of chronic stress. Thus, given the evidence showing a strong correlation between chronic stress and chronic pain, we aim to review and identify overlapping factors and processes. We first explore the predisposing factors and psychologic features common to both conditions. This is followed by examining the overlapping neural circuitry of pain and stress in order to trace a common pathophysiologic processes for the development of chronic pain and its link to substance use. Based on the previous literature and our own findings, we propose a critical role for ventromedial prefrontal cortex dysfunction, an overlapping brain area associated with the regulation of both pain and stress that is also affected by substance use, as key in the risk of developing chronic pain. Finally, we identify the need for future research in exploring the role of medial prefrontal circuits in chronic pain pathology. Critically, in order to alleviate the enormous burden of chronic pain without exacerbating the co-occurring substance misuse crisis, we emphasize the need to find better approaches to treat and prevent chronic pain.

Blunted neural reward response to alcohol and greater alcohol motivation in binge drinkers in a randomized clinical experiment

BACKGROUND

Alcohol stimulates cerebral blood flow (CBF) in brain reward regions. However, neural processes that support sustained alcohol motivation after the first drink are not well understood.

METHODS

Using a novel placebo-controlled, randomized, crossover experiment, 27 individuals who binge drink (BD; 15 M, 12 F) and 25 social drinkers (SD; 15 M, 10 F) underwent a behavioral test of self-motivated alcohol consumption using an Alcohol Taste Test (ATT) involving alcoholic and nonalcoholic beer on separate days. The test was followed immediately by perfusion functional magnetic resonance imaging (fMRI). On both days, participants then engaged in a post-scan ATT with placebo beer to assess sustained alcohol self-motivation without active alcohol effects. Linear mixed effects models were used to examine the effects of drinking group on the placebo-controlled effect of initial alcohol motivation on brain perfusion (whole brain corrected p < 0.001, cluster corrected p < 0.025) and on the relationship between placebo-controlled brain perfusion and sustained alcohol motivation.

RESULTS

Initial alcohol self-motivation in the alcohol relative to placebo session led to markedly decreased activation in the medial orbitofrontal cortex (OFC) and the ventral striatum in BD relative to SD, indicative of neural reward tolerance. The BD group also showed an enhanced neural response in behavioral intention regions of the supplementary motor area (SMA) and inferior frontal gyrus (IFG) regions. Moreover, there was greater sustained alcohol motivation in BD than SD in the post-scan ATT in the alcohol relative to placebo session. Correspondingly, only in BD and only in the alcohol session, lower alcohol-induced OFC response correlated with concurrent sensitized SMA response, and each predicted the subsequent sustained higher alcohol motivation in the post-scan ATT.

CONCLUSIONS

Alcohol-related OFC tolerance may play an important role in sustained alcohol motivation. Furthermore, both specific alcohol-related neural reward tolerance and premotor sensitization responses may contribute to escalating alcohol motivation to drive excessive alcohol intake, even in individuals without alcohol use disorder.

Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.

Purchasing Under the Influence of Alcohol: The Impact of Hazardous and Harmful Patterns of Alcohol Consumption, Impulsivity, and Compulsive Buying

The current research examined how hazardous and harmful patterns of alcohol consumption, problematic online shopping when drinking alcohol, impulsivity, and compulsive buying were associated with and predicted the frequency of making purchases while under the influence of alcohol. A sample of American adults between the ages of 25 and 64 who reported having at least one drink per week over the past 6 months were surveyed. Regression-based path modeling revealed for those who made online purchases while moderately intoxicated, hazardous and harmful patterns of drinking alcohol and, problematic online shopping when drinking alcohol, predicted the frequency of making purchases while intoxicated. For those who made online purchases while heavily intoxicated, hazardous and harmful patterns of drinking alcohol, impulsivity, problematic online shopping when drinking alcohol, and compulsive buying predicted the frequency of making purchases while intoxicated. We explain our findings by suggesting individuals engage in frequent drunk purchases because they are motivated to alleviate their negative mood states.

Acute alcohol and chronic drinking bidirectionally regulate the excitability of prefrontal cortex vasoactive intestinal peptide interneurons

The prefrontal cortex (PFC) regulates drinking behaviors and affective changes following chronic alcohol use. PFC activity is dynamically modulated by local inhibitory interneurons (INs), which can be divided into non-overlapping groups with distinct functional roles. Within deeper layers of neocortex, INs that express either parvalbumin or somatostatin directly inhibit pyramidal cells. By contrast, the plurality of all remaining INs express vasoactive intestinal peptide (VIP), reside within superficial layers, and preferentially target other types of INs. While recent studies have described adaptations to PFC parvalbumin-INs and somatostatin-INs in alcohol use models, whether ethanol or drinking affect the physiology of PFC VIP-INs has not been reported. To address this gap, we used genetically engineered female and male mice to target VIP-INs in layers 1-3 of prelimbic PFC for whole-cell patch-clamp electrophysiology. We found that ethanol (20 mM, ∼0.09 BEC) application to PFC brain slices enhances VIP-IN excitability. We next examined effects following chronic drinking by providing mice with 4 weeks of intermittent access (IA) ethanol two-bottle choice in the home cage. In these studies, VIP-INs from female and male IA ethanol mice displayed reduced excitability relative to cells from water-only controls. Finally, we assessed whether these effects continue into abstinence. After 7-11 days without ethanol, the hypo-excitability of VIP-INs from male IA ethanol mice persisted, whereas cells from female IA ethanol mice were not different from their controls. Together, these findings illustrate that acute ethanol enhances VIP-IN excitability and suggest these cells undergo pronounced homeostatic changes following long-term drinking.

Sex differences in neural responses to stress and drug cues predicts future drug use in individuals with substance use disorder

BACKGROUND

Substance use disorders (SUDs) are chronically recurring illnesses, where stress and drug cues significantly increase drug craving and risk of drug use recurrence. This study examined sex differences in functional magnetic resonance imaging (fMRI) brain responses to stress and drug cue exposure and assessed their prospective association with future drug use post-treatment.

METHODS

Inpatient, treatment engaged men (N = 46) and women (N = 26) with SUDs, including alcohol, cocaine and/or cannabis use disorders, participated in an fMRI scan that assessed subjective (anxiety, drug craving), heart rate and neural responses to brief individualized script-driven imagery of stress, drug, and neutral-relaxing trials. Prospective follow-up interviews post-treatment assessed future drug use recurrence over 90 days.

RESULTS

During fMRI, stress and drug versus neutral cue exposure led to increased anxiety, heart rate and craving responses (p's < 0.004) in both men and women, but greater drug cue-induced anxiety (p < .017) and higher drug use days during follow-up (p < .006) in women relative to men. In whole brain analyses of stress and drug cues (p < .05 FWE corrected), and in whole brain correlation (p < .05, FWE corrected) with drug use days, significant sex differences revealed drug cue-related striatal hyperactivation (caudate, putamen) in men, but drug cue-related cortico-limbic (insula and dorsolateral prefrontal cortex) hypoactivation and stress-related hypoactivation in the ventromedial prefrontal cortex (VmPFC) in women; and these were significantly associated with higher future drug use days.

CONCLUSIONS

Findings indicate sex-specific pathophysiology of SUD recurrence and support the need for differential treatment development for men and women with SUD to improve drug use outcomes.

Pregnenolone effects on provoked alcohol craving, anxiety, HPA axis, and autonomic arousal in individuals with alcohol use disorder

RATIONALE

Chronic alcohol intake down-regulates GABAergic transmission and reduces levels of neuroactive steroids. These changes are associated with greater stress dysregulation and high alcohol craving which in turn increases relapse risk.

OBJECTIVES

This study tested whether potentiation of the neurosteroid system with pregnenolone (PREG), a precursor to neuroactive steroids and known to increase GABAergic transmission, will normalize chronic alcohol-related stress adaptations in the hypothalamic-pituitary-adrenal (HPA) axis and autonomic responses and reduce alcohol craving to significantly impact relapse risk.

METHODS

Forty-three treatment-seeking individuals with alcohol use disorder (AUD) were randomized to placebo (PBO) or supraphysiologic pregnenolone doses of 300 mg or 500 mg treatment using a parallel-between subject design as part of a larger 8-week pilot clinical trial. In week 2, they participated in a 3-day laboratory experiment where on each day they self-administered the assigned study drug in the laboratory and were then exposed to 5-min personalized guided imagery provocation of stress, alcohol, or neutral/relaxing cues, one condition per day on separate days, in a random, counterbalanced order. Repeated assessments of alcohol craving, anxiety, HPA axis, heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP) and serum pregnenolone levels were made on each day.

RESULTS

Pregnenolone levels were significantly increased in the PREG groups versus PBO. PREG treatment decreased stress- and alcohol cue- induced craving and dose-specifically reduced stress-induced anxiety in the 300 mg/day group. Both PREG doses compared to PBO also normalized CORT/ACTH and increased stress-induced HR, stress- and cue-induced SBP, and in the 300 mg PREG group cue-induced DBP responses relative to neutral condition.

CONCLUSIONS

Findings indicate that pregnenolone decreases stress- and alcohol cue-provoked craving and normalizes HPA axis and autonomic arousal in individuals with AUD, thereby supporting the need for further assessment of pregnenolone in the treatment of AUD.

Neural correlates linking trauma and physical symptoms

Trauma and chronic pain frequently co-occur, but the underlying neurological mechanisms are poorly understood. The current study investigated the neural correlates of stress and physical symptoms in trauma patients using functional magnetic resonance imaging (fMRI) and follow-up smartphone surveys. Participants were 10 patients diagnosed with Trauma- and Stressor-Related Disorders and 18 demographically-matched healthy controls who completed a fMRI stress provocation task in which they viewed stressful and neutral-relaxing images. Subsequently, participants completed daily smartphone surveys which prospectively monitored their stress and physical symptoms for 30 days. The trauma group experienced a significantly higher frequency of physical symptoms than controls during the follow-up period. During stress, trauma patients exhibited increased activity in the hippocampus, insula, and sensorimotor areas, but decreased activity in the ventromedial prefrontal cortex (vmPFC), lateral prefrontal cortex (LPFC), and dorsal striatum relative to controls. In all participants, higher physical symptom frequency was significantly associated with a hyperactive left hippocampal response to stress. The current study reports that trauma is characterized by greater physical symptoms and decreased prefrontal but increased limbic responses to stress. Our findings suggest that trauma may increase physical health symptoms by compromising hippocampal function, which could also increase vulnerability to stress- and pain-related disorders.

Alcohol’s Negative Emotional Side: The Role of Stress Neurobiology in Alcohol Use Disorder

This article is part of a Festschrift commemorating the 50th anniversary of the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Established in 1970, first as part of the National Institute of Mental Health and later as an independent institute of the National Institutes of Health, NIAAA today is the world’s largest funding agency for alcohol research. In addition to its own intramural research program, NIAAA supports the entire spectrum of innovative basic, translational, and clinical research to advance the diagnosis, prevention, and treatment of alcohol use disorder and alcohol-related problems. To celebrate the anniversary, NIAAA hosted a 2-day symposium, “Alcohol Across the Lifespan: 50 Years of Evidence-Based Diagnosis, Prevention, and Treatment Research,” devoted to key topics within the field of alcohol research. This article is based on Dr. Sinha’s presentation at the event. NIAAA Director George F. Koob, Ph.D., serves as editor of the Festschrift.

Targeting prefrontal cortex GABAergic microcircuits for the treatment of alcohol use disorder

Developing novel treatments for alcohol use disorders (AUDs) is of paramount importance for improving patient outcomes and alleviating the suffering related to the disease. A better understanding of the molecular and neurocircuit mechanisms through which alcohol alters brain function will be instrumental in the rational development of new efficacious treatments. Clinical studies have consistently associated the prefrontal cortex (PFC) function with symptoms of AUDs. Population-level analyses have linked the PFC structure and function with heavy drinking and/or AUD diagnosis. Thus, targeting specific PFC cell types and neural circuits holds promise for the development of new treatments. Here, we overview the tremendous diversity in the form and function of inhibitory neuron subtypes within PFC and describe their therapeutic potential. We then summarize AUD population genetics studies, clinical neurophysiology findings, and translational neuroscience discoveries. This study collectively suggests that changes in fast transmission through PFC inhibitory microcircuits are a central component of the neurobiological effects of ethanol and the core symptoms of AUDs. Finally, we submit that there is a significant and timely need to examine sex as a biological variable and human postmortem brain tissue to maximize the efforts in translating findings to new clinical treatments.

Alcohol dependence inpatients classification with GLM and hierarchical clustering integration using fMRI data of alcohol multiple scenario cues

Alterations in brain reactions to alcohol-related cues are a neurobiological characteristic of alcohol dependence (AD) and a prospective target for achieving substantial treatment effects. However, a robust prediction of the differences in inpatients' brain responses to alcohol cues during the treatment process is still required. This study offers a data-driven approach for classifying AD inpatients undertaking alcohol treatment protocols based on their brain responses to alcohol imagery with and without drinking actions. The brain activity of thirty inpatients with AD undergoing treatment was scanned using functional magnetic resonance imaging (fMRI) while seeing alcohol and matched non-alcohol images. The mean values of brain regions of interest (ROI) for alcohol-related brain responses were obtained using general linear modeling (GLM) and subjected to hierarchical clustering analysis. The proposed classification technique identified two distinct subgroups of inpatients. For the two types of cues, subgroup one exhibited significant activation in a wide range of brain regions, while subgroup two showed mainly decreased activation. The proposed technique may aid in detecting the vulnerability of the classified inpatient subgroups, which can suggest allocating the inpatients in the classified subgroups to more effective therapies and developing prognostic future relapse markers in AD.

A review of functional brain differences predicting relapse in substance use disorder: Actionable targets for new methods of noninvasive brain stimulation

Neuroimaging studies have identified a variety of brain regions whose activity predicts substance use (i.e., relapse) in patients with substance use disorder (SUD), suggesting that malfunctioning brain networks may exacerbate relapse. However, this knowledge has not yet led to a marked improvement in treatment outcomes. Noninvasive brain stimulation (NIBS) has shown some potential for treating SUDs, and a new generation of NIBS technologies offers the possibility of selectively altering activity in both superficial and deep brain structures implicated in SUDs. The goal of the current review was to identify deeper brain structures involved in relapse to SUD and give an account of innovative methods of NIBS that might be used to target them. Included studies measured fMRI in currently abstinent SUD patients and tracked treatment outcomes, and fMRI results were organized with the framework of the Addictions Neuroclinical Assessment (ANA). Four brain structures were consistently implicated: the anterior and posterior cingulate cortices, ventral striatum and insula. These four deeper brain structures may be appropriate future targets for the treatment of SUD using these innovative NIBS technologies.

Irregular Autonomic Modulation Predicts Risky Drinking and Altered Ventromedial Prefrontal Cortex Response to Stress in Alcohol Use Disorder

AIMS

Autonomic dysfunction has been associated with risky drinking and alcohol use disorder (AUD). Although autonomic nervous system (ANS) activity has been attributed to the ventromedial prefrontal cortex (VmPFC)-limbic-striatal regions, the specific role of ANS disruption in AUD and its association with these regions remain unclear. Using functional magnetic resonance imaging (fMRI) and concurrent electrocardiogram (ECG), the current study examined neural correlates of ANS activity in AUD and its role in AUD pathology.

METHODS

Demographically matched 20 AUD patients and 20 social drinkers (SD) completed an fMRI task involving repeated exposure to stress, alcohol-cue and neutral-relaxing images in a block design. Based on the known VmPFC-limbic-striatal functions involved in emotions, reward and the ANS, we performed a regions of interest (ROI) analysis to examine the associations between ANS activity and neural responses in the VmPFC, amygdala, and ventral striatum.

RESULTS

Across conditions, AUD patients showed significantly higher levels of overall heart rate (HR) and approximate entropy (ApEn) compared to SD (Ps < 0.05). In all participants, increased HR was associated with greater drinking volume (P < 0.05). In addition, higher ApEn levels were associated with greater drinking volume (P < 0.05) and decreased right VmPFC response to stress (P < 0.05).

DISCUSSION

Our findings demonstrate ANS disruption in AUD indexed by high overall HR and ApEn. The association between ApEn and rVmPFC response suggests that ApEn may play a role in modulating drinking via interactions with neural regions of emotion regulation. These findings provide insight into patterns of ANS disruption and their relevance to AUD pathology.

Compounding Vulnerability in the Neurocircuitry of Addiction: Longitudinal Functional Connectivity Changes in Alcohol Use Disorder

AIMS

The addiction neurocircuitry model describes the role of several brain circuits (drug reward, negative emotionality and craving/executive control) in alcohol use and subsequent development of alcohol use disorder (AUD). Human studies examining longitudinal change using resting-state functional magnetic resonance imaging (rs-fMRI) are needed to understand how functional changes to these circuits are caused by or contribute to continued AUD.

METHODS

In order to characterize how intrinsic functional connectivity changes with sustained AUD, we analyzed rs-fMRI data from individuals with (n = 18; treatment seeking and non-treatment seeking) and without (n = 21) AUD collected on multiple visits as part of various research studies at the NIAAA intramural program from 2012 to 2020.

RESULTS

Results of the seed correlation analysis showed that individuals with AUD had an increase in functional connectivity over time between emotionality and craving neurocircuits, and a decrease between executive control and reward networks. Post hoc investigations of AUD severity and alcohol consumption between scans revealed an additive effect of these AUD features in many of the circuits, such that more alcohol consumption or more severe AUD was associated with more pronounced changes to synchronicity.

CONCLUSIONS

These findings suggest an increased concordance of networks underlying emotionality and compulsions toward drinking while also a reduction in control network connectivity, consistent with the addiction neurocircuitry model. Further, they suggest a compounding effect of continued heavy drinking on these vulnerabilities in neurocircuitry. More longitudinal research is necessary to understand the trajectories of individuals with AUD not adequately represented in this study, as well as whether this can inform effective harm reduction strategies.

Prefrontal cortex parvalbumin interneurons exhibit decreased excitability and potentiated synaptic strength after ethanol reward learning

The prefrontal cortex (PFC) is intimately associated with behavioral characteristics of alcohol use disorders, including high motivation to drink and difficulty with moderation. Thus, continued mechanistic research investigating PFC cells and targets altered by ethanol experiences should inform translational efforts to craft new, efficacious treatments. Inhibitory interneurons expressing parvalbumin (PV-INs) comprise only a minor fraction of cells within the PFC, yet these cells are indispensable for coordinating PFC ensemble function, oscillatory activity, and subcortical output. Based on this, PV-INs represent an exciting target for the rational design of breakthrough treatments for alcohol use disorders. Here, we assessed experience-dependent physiological adaptations via ethanol place conditioning. By manipulating the timing of administration relative to conditioning sessions, equivalent ethanol exposure can form either rewarding or aversive memories in different individuals. Here, we found that female mice and male mice on a C57BL/6J background display conditioned place preference (CPP) or aversion (CPA) to an intoxicating dose of ethanol (2 g/kg, intraperitoneal [i.p.]) without overt differences between sexes. Ethanol reward learning was associated with decreased PV-IN excitability in deep layer prelimbic PFC, whereas PV-INs from CPA mice were not different from controls. Furthermore, PV-INs from mice in the CPP group, but not the CPA group, displayed potentiated excitatory synaptic strength that emerged during 1 week of abstinence. Taken together, these findings illustrate that synaptic and intrinsic adaptations associated with ethanol can depend on an individual's experience. These studies provide further context and support for PFC PV-INs as intriguing targets for modulating alcohol associations.

Sex moderates effects of alcohol and cannabis co-use on alcohol and stress reactivity

BACKGROUND

Simultaneous or concurrent use (co-use) of alcohol and cannabis is associated with greater use of both substances over time, academic difficulties, more severe substance use consequences, and adverse impacts on cognitive functioning than the use of a single substance or no substance use. This study examined potential neural mechanisms underlying co-use behaviors in comparison to single substance use. Specifically, we compared alcohol cue reactivity and stress-cue reactivity among individuals who reported frequent same-day co-use of alcohol and cannabis and individuals who reported only alcohol use.

METHODS

The sample included 88 individuals (41 women) who reported only alcohol use and 24 individuals (8 women) who reported co-use of alcohol and cannabis on at least 50% of drinking occasions. All participants completed fMRI stress and alcohol cue reactivity tasks. Because of known sex effects on stress reactivity and alcohol cue reactivity, we tested sex by co-use interactions.

RESULTS

During alcohol cue presentation, co-users had less activation in the thalamus and dorsomedial prefrontal cortex than alcohol-only users, effects that were driven by differences in responses to neutral cues. Examination of stress cue reactivity revealed sex by co-use interactions in the lingual gyrus, with women co-users showing a greater difference between negative and neutral cue reactivity than all other groups. In addition, women co-users had greater connectivity between the nucleus accumbens and both the medial orbitofrontal cortex and the rostral anterior cingulate cortex during negative cue presentation than the other groups.

CONCLUSIONS

These results provide preliminary evidence of enhanced stress cue reactivity in individuals reporting co-use of alcohol and cannabis, particularly women co-users.

Alcohol withdrawal symptoms predict corticostriatal dysfunction that is reversed by prazosin treatment in alcohol use disorder

Chronic alcohol use increases risk of alcohol withdrawal symptoms (AW) and disrupts stress biology and resilient coping, thereby promoting excessive alcohol intake. Chronic alcohol intake and multiple alcohol detoxifications are known to impair brain medial prefrontal cortex (mPFC) and striatal functioning, regions involved in regulating stress, craving and alcohol intake. In two related studies, we examined whether AW predicts this functional brain pathology and whether Prazosin versus Placebo treatment may reverse these effects. In Study 1, patients with Alcohol Use Disorder (AUD) (N = 45) with varying AW levels at treatment entry were assessed to examine AW effects on corticostriatal responses to stress, alcohol cue and neutral visual images with functional magnetic resonance imaging (fMRI). In Study 2, 23 AUD patients entering a 12-week randomised controlled trial (RCT) of Prazosin, an alpha1 adrenergic antagonist that decreased withdrawal-related alcohol intake in laboratory animals, participated in two fMRI sessions at pretreatment and also at week 9-10 of chronic treatment (Placebo: N = 13; Prazosin: N = 10) to assess Prazosin treatment effects on alcohol-related cortico-striatal dysfunction. Study 1 results indicated that higher AW predicted greater disruption in brain mPFC and striatal response to stress and alcohol cues (p < 0.001, family-wise error [FWE] correction) and also subsequently greater heavy drinking days (HDD) in early treatment (p < 0.01). In Study 2, Prazosin versus Placebo treatment reversed mPFC-striatal dysfunction (p < 0.001, FWE), which in turn predicted fewer drinking days (p < 0.01) during the 12-week treatment period. These results indicate that AW is a significant predictor of alcohol-related prefrontal-striatal dysfunction, and Prazosin treatment reversed these effects that in turn contributed to improved alcohol treatment outcomes.

Depicting People in Visual Cues Affects Alcohol Cue Reactivity in Male Alcohol-Dependent Patients

Cue reactivity is often used to study alcohol cues brain responses. Standardized image sets are used, but the effect of viewing people interacting with the alcohol drink remains unclear, which is associated with the factors of alcohol cues that influence the degree of response to alcohol stimuli. The present study used fMRI to investigate the reactivity of alcohol dependence (AD) inpatients to alcohol cues with or without human drinking behavior. Cues with a human interacting with a drink were hypothesized to increase sensorimotor activation. In total, 30 AD inpatients were asked to view pictures with a factorial design of beverage types (alcoholic vs. non-alcoholic beverages) and cue types (with or without drink action). Whole-brain analyses were performed. A correlation analysis was conducted to confirm whether the whole-brain analysis revealed cue-related brain activations correlated with problem drinking duration. The left lingual gyrus showed significant beverage types through cue type interaction, and the bilateral temporal cortex showed significant activation in response to alcohol cues depicting human drinking behavior. The right and left lingual gyrus regions and left temporal cortex were positively correlated with problem drinking duration. Sensorimotor activations in the temporal cortex may reflect self-referential and memory-based scene processing. Thus, our findings indicate these regions are associated with alcohol use and suggest them for cue exposure treatment of alcohol addiction.

Alcohol craving and withdrawal at treatment entry prospectively predict alcohol use outcomes during outpatient treatment

OBJECTIVE

Chronic alcohol use increases risk of alcohol craving and withdrawal symptoms (AW) as well as abstinence-related distress symptoms, in those entering alcohol use disorder (AUD) treatment. Here, we examined whether AW and alcohol craving in AUD patients entering outpatient treatment prospectively predicts future heavy drinking days/week (HDD) and additional alcohol use outcomes during 8-weeks of outpatient treatment, and their relationship to abstinence symptoms of depression, anxiety and sleep difficulties.

METHODS

Participants were 80 treatment-seeking adults with current DSM-5 AUD (39% female; 43% White; 20-60 years) who completed assessments of AW and alcohol craving and also alcohol abstinence symptoms of depression, anxiety, and sleep quality at treatment intake. Participants were prospectively followed using daily diaries for alcohol intake during 8-week of standardized weekly relapse prevention counseling to support recovery.

RESULTS

After accounting for demographic and pre-treatment alcohol use, greater alcohol craving at treatment entry predicted higher HDD (p < .013) as well as greater drinking days (DD: p < .004), average drinks per drinking day/week (AvgD: p < .001) and relapse to heavy drinking (p < .05), while higher levels of pretreatment AW symptoms interacted with treatment week to predict greater HDD (p < .018). Abstinence symptoms of depression, anxiety, and sleep difficulties were associated with craving and AW but did not predict any drinking-related outcomes.

CONCLUSIONS

These results provide evidence that increased alcohol craving and AW may serve as prognostic indicators of greater risk of heavy drinking in outpatient treatment. Findings suggest the need to evaluate craving and AW at outpatient treatment entry and develop targeted treatments to specifically address the effects of craving and AW on drinking outcomes in outpatient AUD treatment.

Social Support Effects on Neural Stress and Alcohol Reward Responses

Social support (SS), or having people to depend on during times of stress, may offer an emotional and neurological buffer to problem drinking. Specifically, SS may modulate reward and stress-related brain responses to mitigate perceptions of alcohol reward and stress. There is limited evidence, however, on this topic and specifically on brain networks that may modulate SS effects on stress and alcohol reward. Here we present a review of the current literature on this topic as well as data from a large community sample of 115 social drinkers. Findings from a novel fMRI task viewing alcohol cue, stress, and neutral images, in separate blocks, while providing ratings on subjective feelings of alcohol craving, stress, and arousal are included. Lower SS significantly predicted greater alcohol craving during alcohol cue and stress conditions, higher baseline levels of stress, and greater arousal in the alcohol cue, relative to neutral condition. Remarkably, individuals with low SS showed greater reward activation (ventral medial prefrontal cortex (VmPFC) and ventral striatum) during alcohol cue exposure, while those with high SS showed no such activation (p < 0.001, family wise error corrected at 0.05). Furthermore, individuals with lower SS showed greater stress circuit (VmPFC, dorsal striatum, and periaqueductal gray) activation not observed in the high SS groups. Both groups showed increased amygdala activation under stress condition. The findings support the notion that SS is a powerful modulator of stress response and reward motivation. High SS buffers neural and subjective stress responses, while low SS potentiates greater reward seeking with higher alcohol craving and greater brain activation during alcohol cue exposure. Previous research and current results suggest the need to further explore the role of SS in those at risk of developing alcohol use disorder and assess novel prevention strategies to boost SS in at-risk drinkers.

Increased decision latency in alcohol use disorder reflects altered resting-state synchrony in the anterior salience network

Increased decision latency in alcohol use disorder (AUD) has been generally explained in terms of psychomotor slowing. Recent results suggest that AUD patients' slowed decision-making might rather reflect alterations in the neural circuitry underlying the engagement of controlled processing by salient stimuli. We addressed this hypothesis by testing a relationship between decision latency at the Cambridge Gambling Task (CGT) and intrinsic brain activity in 22 individuals with AUD and 19 matched controls. CGT deliberation time was related to two complementary facets of resting-state fMRI activity, i.e. coherence and intensity, representing early biomarkers of functional changes in the intrinsic brain architecture. For both metrics, we assessed a multiple regression (to test a relationship with deliberation time in the whole sample), and an interaction analysis (to test a significantly different relationship with decision latency across groups). AUD patients' slowed deliberation time (p < 0.025) reflected distinct facets of altered intrinsic activity in the cingulate node of the anterior salience network previously associated with the "output" motor stage of response selection. Its heightened activity in AUD patients compared with controls, tracking choice latency (p < 0.025 corrected), might represent a compensation mechanism counterbalancing the concurrent decrease of its internal coherent activity (p < 0.025 corrected). These findings provide novel insights into the intrinsic neural mechanisms underlying increased decision latency in AUD, involving decreased temporal synchronicity in networks promoting executive control by behaviourally relevant stimuli. These results pave the way to further studies assessing more subtle facets of decision-making in AUD, and their possible changes with rehabilitative treatment.

Sustained brain response to repeated drug cues is associated with poor drug-use outcomes

A threefold increase in fatal cocaine overdoses during the past decade highlights the critical lack of medications for cocaine use disorders. The brain response to drug cues can predict future drug use; however, results have been mixed. We present preliminary evidence that a sustained response to repeated cocaine cues within a single task is a significant predictor of drug-use outcomes. Seventy-three cocaine inpatients were administered a passive-viewing fMRI task, featuring 500 ms novel evocative (cocaine, sexual, aversive) and neutral comparator cues in the first half (Half1), which were then repeated in the second half (Half2). After the baseline scan, patients received eight outpatient treatment weeks with twice-weekly drug screens. Drug-use outcome groups were empirically defined based on cocaine-positive or missing urines averaged across the outpatient phase: GOOD (<40%), POOR (>85%), and Intermediate (INT, between 40% and 85%) outcomes. Differences of response to initial (Half1) and repeated (Half2) cues in a priori (cue-reactive) regions were tested between outcome groups (3 [Group] × 2 [Halves] ANOVA). An interaction was found in the brain response to drug (but not sex or aversive) cues, with a significant difference between the GOOD and POOR outcome groups in Half2, driven by a significant decrease in brain response by the GOOD outcome group and a sustained brain response by the POOR outcome group, to repeated cocaine cues. The brain response to repeated drug cues may be a useful predictor of future drug use, encouraging future intervention studies to restore a "healthy" (decreasing) response to the repeated presentation of drug cues.

Alterations in connectivity of the bed nucleus of the stria terminalis during early abstinence in individuals with alcohol use disorder

BACKGROUND

For individuals with Alcohol Use Disorder (AUD), long-term recovery is difficult in part due to symptoms of anxiety that occur during early abstinence and can trigger relapse. Research in rodent models of AUD has identified the bed nucleus of the stria terminalis (BNST), a small, sexually dimorphic, subcortical region, as critical for regulating anxiety-like behaviors during abstinence, particularly in female mice. Furthermore, prolonged alcohol use and subsequent abstinence alter BNST afferent and efferent connections to other brain regions. To our knowledge, however, no studies of early abstinence have investigated BNST structural connectivity in humans during abstinence; this study addresses that gap.

METHODS

Nineteen participants with AUD currently in early abstinence and 20 healthy controls completed a diffusion tensor imaging (DTI) scan. BNST structural connectivity was evaluated using probabilistic tractography. A linear mixed model was used to test between-groups differences in BNST network connectivity. Exploratory analyses were conducted to test for correlations between BNST connectivity and alcohol use severity and anxiety within the abstinence group. Sex was included as a factor for all analyses.

RESULTS

The BNST showed stronger structural connectivity with the BNST network in early abstinence women than in control women, which was not seen in men. Women also showed region-specific differences, with stronger BNST-hypothalamus structural connectivity but weaker vmPFC-BNST structural connectivity than men. Exploratory analyses also demonstrated a relationship between alcohol use severity and vmPFC-BNST structural connectivity that was moderated by sex.

CONCLUSIONS

This study is the first to demonstrate BNST structural connectivity differences in early abstinence and revealed key sex differences. The sex-specific differences in BNST structural connectivity during early abstinence could underlie known sex differences in abstinence symptoms and relapse risk and help to inform potential sex-specific treatments.

Increased Synaptic Strength and mGlu2/3 Receptor Plasticity on Mouse Prefrontal Cortex Intratelencephalic Pyramidal Cells Following Intermittent Access to Ethanol

BACKGROUND

The medial prefrontal cortex (PFC) is crucial for regulating craving and alcohol seeking in alcohol use disorder (AUD) patients and alcohol seeking in animal models. Maladaptive changes in volitional ethanol (EtOH) intake have been associated with PFC function, yet synaptic adaptations within PFC have not been consistently detected in voluntary drinking rodent models. At least 80% of the neurons in PFC are glutamatergic pyramidal cells. Pyramidal cells provide the predominant cortical output to several brain regions relevant to AUD, including structures within the telencephalon (IT: e.g., basal ganglia, amygdala, other neocortical regions) and outside the telencephalon (ET: e.g., lateral hypothalamus, midbrain monoaminergic structures, thalamus).

METHODS

In addition to their anatomical distinctions, studies from several laboratories have revealed that prefrontal cortical IT and ET pyramidal cells may be differentiated by specific electrophysiological parameters. These distinguishable parameters make it possible to readily classify pyramidal cells into separable subtypes. Here, we employed and validated the hyperpolarization sag ratio as a diagnostic proxy for separating ET (type A) and IT (type B) neurons. We recorded from deep-layer prelimbic PFC pyramidal cells of mice 1 day after 4 to 5 weeks of intermittent access (IA) EtOH exposure.

RESULTS

Membrane properties were not altered by IA EtOH, but excitatory postsynaptic strength onto IT type B neurons was selectively enhanced in slices from IA EtOH mice. The increased excitatory drive was accompanied by enhanced mGlu_2/3 receptor plasticity on IT type B neurons, providing a potential translational approach to mitigate cognitive and motivational changes to PFC function related to binge drinking.

CONCLUSIONS

Together, these studies provide insight into the specific PFC neurocircuits altered by voluntary drinking. In addition, the findings provide an additional rationale for developing compounds that potentiate mGlu₂ and/or mGlu₃ receptor function as potential treatments for AUD.