Stress-Induced Sensitization of Insula Activation Predicts Alcohol Craving and Alcohol Use in Alcohol Use Disorder

Glucose intake reduces alcohol craving and amplifies habituation to cue-induced brain activation in male patients with alcohol use disorder: A randomized, placebo-controlled crossover study examining male and female patients with AUD

INTRODUCTION

Evidence suggests a role of appetite-regulating hormones in alcohol use disorder. Reductions in acylated ghrelin levels are associated with reductions in craving and cue-induced brain activity. Ghrelin levels can be physiologically decreased by glucose intake, which therefore could be a treatment reducing craving and cue-induced brain activity in patients with alcohol use disorder, potentially mediated by acylated ghrelin.

MATERIAL AND METHODS

80 males and females with alcohol use disorder participated in the randomized placebo-controlled crossover study, examining glucose intake as acute treatment to reduce craving. Changes in craving and ghrelin levels were assessed at eight time points. Of these, 43 participants attended fMRI measurements examining habituation to cue-induced brain activation over time. Craving and hormone levels over time were analyzed using linear mixed modeling, brain activation habituation over time using flexible factorial models.

RESULTS

Models revealed a significant interaction effect (F(1,474.607)= 13.563, p < .001) between sex and treatment on craving, with lower craving values in males (difference in means=-.540, p = .016, 95 %CI: -.976, -.103) and higher craving in females (difference in means=.815, p = .005, 95 %CI:.243, 1.387) in the glucose compared to the placebo condition. In males, we found a significant effect of treatment (F(1,313.602)= 7.811, p = .006) and a trend, but no significant effect of acylated ghrelin (F(1,301.568)= 3.574, p = .060) on craving as well as greater habituation to cue-induced brain activation after glucose compared to placebo intake in right putamen (T(1,35)= 4.77, p = .019). Individual habituation slopes significantly predicted the difference in craving before and after the alcohol task (F(2,36)= 5.234, p = .010; B= -36.018, p = .027) in males.

CONCLUSIONS

Glucose intake could be a short-term treatment for males with alcohol use disorder to reduce alcohol craving and cue-induced brain activation. Sex-specific differences should be considered to gain a better understanding of the underlying mechanisms and develop treatment options for females.

Comparative analysis of functional network dynamics in high and low alcohol preference mice

Individual variability preference is a typical characteristic of alcohol drinking behaviors, with a higher risk for the development of alcohol use disorders (AUDs) in high alcohol preference (HP) populations. Here, we created a map of alcohol-related brain regions through c-Fos profiling, and comparatively investigated the differences of functional neural networks between the HP mice and low alcohol preference (LP) mice. We found that neuronal activity in some brain regions, such as ventral tegmental area (VTA), was altered in both HP and LP mice, indicating that these neurons were universally sensitive to alcohol. Most importantly, several brain regions, such as the prefrontal cortex and insular cortex, exhibited significantly higher c-Fos expression in HP mice than that in LP mice and displayed broader and stronger neural connections across brain networks, suggesting that these brain regions are the potential targets for individual alcohol preference. Graph theory-based analysis unraveled a decrease in brain modularity in HP networks, yet with more centralized connection patterns, and maintained higher communication efficiency and redundancy. Furthermore, LP mice switched the central network hubs, with the key differential network centered on nucleus accumbens shell (NAc Sh), nucleus accumbens core (NAc C), VTA, and anterior insular cortex (AIC), indicating that these brain regions and related neural circuits, such as NAc Sh-AIC may be involved in regulating individual alcohol preference. These results provide novel insights into the neural connections governing individual preferences to alcohol consumption, which may contribute to AUDs prediction and pharmacotherapy.

Acute cannabidiol administration reduces alcohol craving and cue-induced nucleus accumbens activation in individuals with alcohol use disorder: the double-blind randomized controlled ICONIC trial

Although alcohol use disorder (AUD) is highly prevalent, only a few medications are approved for its treatment leaving much room for improvement. Cannabidiol (CBD) might be a particularly promising candidate, with preclinical data suggesting that CBD is effective in targeting AUD symptoms and disease processes that drive alcohol use and relapse, due to its anti-craving, stress-reducing, and anti-compulsive effects. Here we report data from the double-blind randomized controlled ICONIC trial that compared the effects of a single dose of 800 mg cannabidiol against placebo (PLC) in N = 28 individuals with AUD. Cue-induced nucleus accumbens (NAc) activation, alcohol craving during a combined stress- and alcohol cue exposure session, as well as craving during an fMRI alcohol cue-reactivity task and CBD plasma levels served as outcomes. Individuals receiving CBD showed lower bilateral cue-induced NAc activation (tleft_NAc(23) = 4.906, p < 0.001, d = 1.15; tright_NAc (23) = 4.873, p < 0.001, d = 1.13) and reported significantly lower alcohol craving after a combined stress- and alcohol cue exposure session (Fgroup(1,26) = 4.516, p = 0.043, eta2 = 0.15) and during the fMRI cue-reactivity task (Fgroup(1,24) = 6.665, p = 0.015, eta2 = 0.23). CBD levels were significantly higher in the CBD group (t(25) = 3.808, p < 0.001, d = 1.47) and showed a significant negative association with alcohol craving during the cue exposure experiment (r = -0.394, pFDR = 0.030) and during fMRI (r = -0.389, pFDR = 0.030), and with left and right NAc activation (rleft_NAc = -0.459, pFDR = 0.030; rright_NAc = -0.405, pFDR = 0.030). CBD's capacity to reduce stress- and cue-induced alcohol craving and to normalize NAc activation - a region critical to the pathophysiology of AUD - contribute to understanding the neurobiological basis of its clinical effects and support its potential as a treatment option for AUD. Clinical Trials Registry: DRKS00029993.

Insights into Overlapping Brain Networks for Anxiety and Alcohol Use Disorders

Alcohol use disorder (AUD) is a debilitating condition affecting over 30 million Americans. AUD commonly co-occurs with other disorders, like other substance use disorders, trauma-related disorders, and anxiety disorders. Of the numerous co-occurring disorders, anxiety disorders are the most pervasive: anxiety disorders serve as a risk factor for developing AUD, emerge as co-occurring disorders that maintain alcohol drinking, and impede the effectiveness of treatments for AUD. Anxiety, therefore, shapes the development, course, and treatment of AUDs. AUDs can also increase anxiety, suggesting a complex, bidirectional relation between alcohol use and anxiety. The intersection of AUDs and anxiety is also supported by their overlapping neural circuits, specifically neural circuits involved in stress responding, reward processing, and cognitive control. The current review highlights findings from several decades of research on how anxiety impacts the brain and treatment outcomes in AUDs. We also provide important considerations for future research, with the goal of reducing the shame and burden of alcohol use for individuals with AUD and their families.

Retrieval of an Ethanol-Conditioned Taste Aversion Promotes GABAergic Plasticity in the Anterior Insular Cortex

Blunted sensitivity to ethanol's aversive effects can increase motivation to consume ethanol; yet, the neurobiological circuits responsible for encoding these aversive properties are not fully understood. Plasticity in cells projecting from the anterior insular cortex (aIC) to the basolateral amygdala (BLA) is critical for taste aversion learning and retrieval, suggesting this circuit's potential involvement in modulating the aversive properties of ethanol. Here, we tested the hypothesis that GABAergic currents onto aIC→BLA projections would be facilitated as a consequence of retrieval of an ethanol-conditioned taste aversion (CTA). Consistent with this hypothesis, frequency of mIPSCs was increased 1 h following retrieval of an ethanol-CTA across cell layers in aIC→BLA projection neurons. This increase in GABAergic plasticity occurred in a circuit-specific, time-limited, and ethanol-CTA retrieval-dependent manner. Additionally, local inhibitory inputs onto layer 2/3 aIC→BLA projection neurons were greater in number and strength following ethanol-CTA. Finally, DREADD-mediated inhibition of aIC parvalbumin-expressing cells blunted the retrieval of ethanol-CTA in male, but not female, mice. Collectively, this work implicates a circuit-specific and memory retrieval-dependent increase in GABAergic tone following retrieval of an ethanol-CTA, thereby advancing our understanding of how the aversive effects of ethanol are encoded in the brain.

A stress-activated mid-insula to BNST pathway regulates susceptibility to abstinence-induced negative affect in female mice

Stress is central to many neuropsychiatric conditions, including alcohol use disorder (AUD). Stress influences the initiation and continued use of alcohol, the progression to AUD, and relapse. Identifying the neurocircuits activated during stress, and individual variability in these responses is critical for developing new treatment targets for AUD, particularly to mitigate stress-induced relapse. Using a longitudinal approach, this study examined the relationship between sub-chronic stress exposure and negative affect during protracted abstinence following chronic ethanol exposure. Sub-chronic restraint stress heightened negative affect-like behavior in protracted abstinence. Interestingly, this was driven by a subset of "stress-susceptible" female mice. We examined the mid-insula, a hub in the brain's salience network, as a driver of this effect, given its role in emotional regulation and links to alcohol craving, consumption, and abstinence-induced negative affect. Mid-insula GCaMP fiber photometry revealed that GCaMP activity during stress exposure was positively correlated with activity during the novelty-suppressed feeding test (NSFT) two weeks into abstinence. A distinct subset of mice exhibited increasing activity during the consummatory phase, implicating the mid-insula as a neural basis for heightened negative affect in abstinence. Chemogenetic inhibition of mid-insula neurons projecting to the dorsal BNST during stress disrupted the emergence of stress susceptibility, highlighting this circuit as a key determinant of susceptibility to abstinence-induced negative affect. These outcomes were female-specific, addressing a critical gap in understanding AUD risk in women. Furthermore, female mice exhibited higher struggling behavior during stress than males. However, this effect was blocked by chemogenetic inhibition of the insula-BNST pathway during stress. By linking pre-alcohol stress response with abstinence outcomes, this work positions the insula-BNST pathway as a potential AUD circuit activity biomarker and therapeutic target.

Association of altered cortical gyrification and working memory in male early abstinent alcohol-dependent individuals

BACKGROUND

Alcohol dependence (AD) is an addictive disorder with multifaceted neurobiological features. Recent research on the pathophysiological mechanisms of AD has emphasized the important role of dysconnectivity. Cortical gyrification is known to be a reliable marker of neural connectivity. This study aimed to explore cortical gyrification using the local gyrification index (LGI) between alcohol-dependent patients and controls.

METHODS

Magnetic resonance images were collected from 60 early abstinent patients with AD (5-12 days after stopping alcohol consumption) and 59 controls and preprocessed using FreeSurfer, followed by surface-based morphometry (SBM) analysis to compare the LGI between the two groups. Cognitive performance was assessed using the Spatial Working Memory (SWM) test in the Cambridge Neuropsychological Test Automated Battery (CANTAB). The relationship between LGI, cognitive performance, and clinical variables was also explored in the patient group.

RESULTS

Compared with controls, patients with AD exhibited significantly decreased LGI in several regions, including the postcentral gyrus, precentral gyrus, middle frontal, superior temporal, middle temporal, insula, superior parietal, and inferior parietal cortex. AD patients did worse than controls in several SWM measures. Furthermore, decreased LGI in the left postcentral was negatively correlated with working memory performance after multiple comparison corrections in the patient group.

CONCLUSION

Alcohol-dependent individuals exhibit abnormal patterns of cortical gyrification, which may be underlying neurobiological markers of AD. Our findings further indicate that working memory deficits may be related to abnormalities in cortical gyrification in alcohol addiction.

Drawbacks to Strengthening Neural Salience Encoding: A Link Between Cortisol and Risky Drinking

Emotionally salient experiences are encoded and remembered more strongly, an effect that can be amplified by hormones like cortisol. Such memories can in turn profoundly influence later behavior. However, little is known about the link between amplified salience encoding and subsequent behavior. This pathway may be particularly important for risky alcohol drinking, which has been linked to sensitized salience responses, memory, and cortisol. To test this possibility, we integrated pharmacology using a double-blind cross-over design with fMRI, cognitive, and motivation assays across a range of healthy male and female social drinkers. As anticipated, cortisol enhanced memory for salient alcohol-related events; critically, this bias was in turn associated with later alcohol motivation. Increased alcohol motivation was particularly pronounced in more susceptible risky drinkers, for whom cortisol enhanced brain salience responses to alcohol. These sensitized salience responses predicted both memory biases and alcohol motivation. Together, these findings reveal maladaptive consequences of enhanced salience encoding.

Neural correlates of proactive avoidance deficits and alcohol use motives in problem drinking

Physical pain and negative emotions represent two distinct drinking motives that contribute to harmful alcohol use. Proactive avoidance, in contrast, can reduce consumption in response to these motives but appears to be impaired in those with problem drinking. Despite such evidence, proactive avoidance and its underlying neural deficits have not been assessed experimentally. How these deficits inter-relate with drinking motives to influence alcohol use also remains unclear. The current study leveraged neuroimaging data in forty-one problem and forty-one social drinkers who performed a probabilistic learning go/nogo task featuring proactive avoidance of painful outcomes. We identified the brain responses to proactive avoidance and contrasted the neural correlates of drinking to avoid negative emotions vs. physical pain. Behavioral results confirmed proactive avoidance deficits in problem drinking individuals' learning rate and performance accuracy, both which were associated with greater alcohol use. Imaging findings in the problem drinking group showed that negative emotions as a drinking motive predicted attenuated right anterior insula activation during proactive avoidance. In contrast, physical pain motive predicted reduced right putamen response. These regions' activations as well as functional connectivity with the somatomotor cortex also demonstrated a negative relationship with drinking severity and positive relationship with proactive avoidance performance. Path modeling further delineated the pathways through which physical pain and negative emotions influenced the neural and behavioral measures of proactive avoidance. Taken together, the current findings provide experimental evidence for proactive avoidance deficits in alcohol misuse and establish the link between their neural underpinnings and drinking behavior.

The ReCoDe addiction research consortium: Losing and regaining control over drug intake-Findings and future perspectives

Substance use disorders (SUDs) are seen as a continuum ranging from goal-directed and hedonic drug use to loss of control over drug intake with aversive consequences for mental and physical health and social functioning. The main goals of our interdisciplinary German collaborative research centre on Losing and Regaining Control over Drug Intake (ReCoDe) are (i) to study triggers (drug cues, stressors, drug priming) and modifying factors (age, gender, physical activity, cognitive functions, childhood adversity, social factors, such as loneliness and social contact/interaction) that longitudinally modulate the trajectories of losing and regaining control over drug consumption under real-life conditions. (ii) To study underlying behavioural, cognitive and neurobiological mechanisms of disease trajectories and drug-related behaviours and (iii) to provide non-invasive mechanism-based interventions. These goals are achieved by: (A) using innovative mHealth (mobile health) tools to longitudinally monitor the effects of triggers and modifying factors on drug consumption patterns in real life in a cohort of 900 patients with alcohol use disorder. This approach will be complemented by animal models of addiction with 24/7 automated behavioural monitoring across an entire disease trajectory; i.e. from a naïve state to a drug-taking state to an addiction or resilience-like state. (B) The identification and, if applicable, computational modelling of key molecular, neurobiological and psychological mechanisms (e.g., reduced cognitive flexibility) mediating the effects of such triggers and modifying factors on disease trajectories. (C) Developing and testing non-invasive interventions (e.g., Just-In-Time-Adaptive-Interventions (JITAIs), various non-invasive brain stimulations (NIBS), individualized physical activity) that specifically target the underlying mechanisms for regaining control over drug intake. Here, we will report on the most important results of the first funding period and outline our future research strategy.

Retrieval of an ethanol-conditioned taste aversion promotes GABAergic plasticity in the insular cortex

Blunted sensitivity to ethanol's aversive effects can increase motivation to consume ethanol; yet, the neurobiological circuits responsible for encoding these aversive properties are not fully understood. Plasticity in cells projecting from the insular cortex (IC) to the basolateral amygdala (BLA) is critical for taste aversion learning and retrieval, suggesting this circuit's potential involvement in modulating the aversive properties of ethanol. Here, we tested the hypothesis that GABAergic activity onto IC-BLA projections would be facilitated following the retrieval of an ethanol-conditioned taste aversion (CTA). Consistent with this hypothesis, frequency of mIPSCs was increased following retrieval of an ethanol-CTA across cell layers in IC-BLA projection neurons. This increase in GABAergic plasticity occurred in both a circuit-specific and learning-dependent manner. Additionally, local inhibitory inputs onto layer 2/3 IC-BLA projection neurons were greater in number and strength following ethanol-CTA. Finally, DREADD-mediated inhibition of IC parvalbumin-expressing cells blunted the retrieval of ethanol-CTA in male, but not female, mice. Collectively, this work implicates a circuit-specific and learning-dependent increase in GABAergic tone following retrieval of an ethanol-CTA, thereby advancing our understanding of how the aversive effects of ethanol are encoded in the brain.

Subjective stress and any drinking during alcohol treatment: Disentangling within and between person autoregressive effects

Alcohol use has been shown to increase stress, and there is some evidence that stress predicts subsequent alcohol use during treatment for alcohol use disorder (AUD), particularly among females who are more likely to report coping-motivated drinking. Gaining a better understanding of the processes by which stress and alcohol use are linked during treatment could potentially inform AUD treatment planning. The current study aimed to characterize the association between stress and drinking during the course of AUD treatment and whether there were sex differences in these associations. Secondary data analyses of the COMBINE study (N = 1375; 69% male, 76.3% non-Hispanic and white, average age of 44.4 years) were conducted to examine self-reported perceived stress and alcohol consumption across 16 weeks of treatment for AUD using a Bayesian random-intercept cross-lagged panel model. There was stronger evidence for any alcohol use predicting greater than typical stress in subsequent weeks and less strong evidence for stress increasing the subsequent probability of alcohol use, particularly among males. For females, greater stress predicted subsequent drinking earlier in the treatment period, and a lower probability of subsequent drinking in the last week of treatment. Interventions might specifically focus on targeting reductions in stress following drinking occasions.

Forced Abstinence from Volitional Ethanol Intake Drives a Vulnerable Period of Hyperexcitability in BNST-Projecting Insular Cortex Neurons

The insular cortex (IC) integrates sensory and interoceptive cues to inform downstream circuitry executing adaptive behavioral responses. The IC communicates with areas involved canonically in stress and motivation. IC projections govern stress and ethanol recruitment of bed nucleus of the stria terminalis (BNST) activity necessary for the emergence of negative affective behaviors during alcohol abstinence. Here, we assess the impact of the chronic drinking forced abstinence (CDFA) volitional home cage ethanol intake paradigm on synaptic and excitable properties of IC neurons that project to the BNST (IC→BNST). Using whole-cell patch-clamp electrophysiology, we investigated IC→BNST circuitry 24 h or 2 weeks following forced abstinence (FA) in female C57BL6/J mice. We find that IC→BNST cells are transiently more excitable following acute ethanol withdrawal. In contrast, in vivo ethanol exposure via intraperitoneal injection, ex vivo via ethanol wash, and acute FA from a natural reward (sucrose) all failed to alter excitability. In situ hybridization studies revealed that at 24 h post FA BK channel mRNA expression is reduced in IC. Further, pharmacological inhibition of BK channels mimicked the 24 h FA phenotype, while BK activation was able to decrease AP firing in control and 24 h FA subjects. All together these data suggest a novel mechanism of homeostatic plasticity that occurs in the IC→BNST circuitry following chronic drinking.