Brain Structure and Function in Recovery

Treadmill Exercise Reshapes Cortical Astrocytic and Neuronal Activity to Improve Motor Learning Deficits Under Chronic Alcohol Exposure

Alcohol abuse induces various neurological disorders including motor learning deficits, possibly by affecting neuronal and astrocytic activity. Physical exercise is one effective approach to remediate synaptic loss and motor deficits as shown by our previous works. In this study, we unrevealed the role of exercise training in the recovery of cortical neuronal and astrocytic functions. Using a chronic alcohol injection mouse model, we found the hyperreactivity of astrocytes along with dendritic spine loss plus lower neuronal activity in the primary motor cortex. Persistent treadmill exercise training, on the other hand, improved neural spine formation and inhibited reactive astrocytes, alleviating motor learning deficits induced by alcohol exposure. These data collectively support the potency of endurance exercise in the rehabilitation of motor functions under alcohol abuse.

Sex and Gender Differences in Co-Occurring Alcohol Use Disorder and PTSD

Purpose of Review

Research demonstrates a strong association between alcohol use disorder (AUD) and posttraumatic stress disorder (PTSD). However, less is known about sex- and gender-based differences among individuals with AUD + PTSD. This narrative review examines recent literature in this area and aims to be a reference for future research endeavors.

Recent Findings

Extant literature shows that intertwining biological systems increase females' risk of developing PTSD and experiencing more adverse effects from AUD compared to males. Sex-based physiological differences further interact with gendered sociocultural environments to influence the risk of AUD + PTSD. Emerging research suggests potential gender-specific pathways between PTSD, coping, and AUD which may inform prevention and treatment. However, barriers to care are often gender-specific and tailored approaches are needed to improve reach and uptake.

Summary

Additional research is needed to examine intersectional and contextual factors that synergistically influence sex/gender differences in AUD + PTSD, particularly beyond cisgender identities, and mechanisms of action.

Preliminary evidence for changes in frontoparietal network connectivity in the early abstinence period in alcohol use disorder: a longitudinal resting-state functional magnetic resonance imaging study

The early abstinence period is a crucial phase in alcohol use disorder (AUD) in which patients have to find a new equilibrium and may start recovery, or conversely, relapse. However, the changes in brain functions during this key period are still largely unknown. We set out to study longitudinal changes in large-scale brain networks during the early abstinence period using resting-state scans. We scanned AUD patients twice in a well-controlled inpatient setting, with the first scan taking place shortly after admission and the second scan 4 weeks (±9 days) later near the end of the treatment period. We studied 37 AUD patients (22 males) and 27 healthy controls (16 males). We focused on three networks that are affected in AUD and underly core symptom dimensions in this disorder: the frontoparietal networks (left and right FPN) and default mode network (DMN). Both the whole brain and within network connectivity of these networks were studied using dual regression. Finally, we explored correlations between these brain networks and various neuropsychological and behavioral measures. In contrast to the controls (Z = -1.081, p = 0.280), the AUD patients showed a decrease in within left FPN connectivity (Z = -2.029, p = 0.042). However, these results did not survive a strict Bonferroni correction. The decrease in left FPN connectivity during the early abstinence period in AUD may reflect an initially upregulated FPN, which recovers to a lower resting-state connectivity level during subsequent weeks of abstinence. The AUD patients showed a trend for a positive association between the change in left FPN connectivity and trait anxiety (rs = 0.303, p = 0.068), and a trend for a negative association between the change in left FPN connectivity and delay discounting (rs = -0.283, p = 0.089) (uncorrected for multiple comparisons). This suggests that the FPN might be involved in top-down control of impulsivity and anxiety, which are important risk factors for relapse. Although there were no statistically significant results (after multiple comparison correction), our preliminary findings encourage further research into the dynamic neuroadaptations during the clinically crucial early abstinence period and could inform future study designs.

WOMEN'S USE OF ALCOHOL: NEUROBIOBEHAVIORAL CONCOMITANTS AND CONSEQUENCES

In this narrative review, we draw from historical and contemporary literature to explore the impact of alcohol consumption on brain and behavior among women. We examine three domains: 1) the impact of alcohol use disorder (AUD) on neurobiobehavioral outcomes, 2) its impact on social cognition/emotion processing, and 3) alcohol's acute effects in older women. There is compelling evidence of alcohol-related compromise in neuropsychological function, neural activation, and brain structure. Investigations of social cognition and alcohol effects in older women represent emerging areas of study. Initial analyses suggest that women with AUD show significant deficits in emotion processing, a finding also observed in older women who have consumed a moderate dose of alcohol. Critically, despite the long-recognized need for programmatic interrogation of alcohol's effect in women, studies with sufficient numbers of women for meaningful analysis represent a small proportion of the literature, constraining interpretation and generalization.

Genome-wide transcriptomics of the amygdala reveals similar oligodendrocyte-related responses to acute and chronic alcohol drinking in female mice

Repeated excessive alcohol consumption is a risk factor for alcohol use disorder (AUD). Although AUD has been more common in men than women, women develop more severe behavioral and physical impairments. However, relatively few new therapeutics targeting development of AUD, particularly in women, have been validated. To gain a better understanding of molecular mechanisms underlying alcohol intake, we conducted a genome-wide RNA-sequencing analysis in female mice exposed to different modes (acute vs chronic) of ethanol drinking. We focused on transcriptional profiles in the amygdala including the central and basolateral subnuclei, brain areas previously implicated in alcohol drinking and seeking. Surprisingly, we found that both drinking modes triggered similar changes in gene expression and canonical pathways, including upregulation of ribosome-related/translational pathways and myelination pathways, and downregulation of chromatin binding and histone modification. In addition, analyses of hub genes and upstream regulatory pathways revealed that voluntary ethanol consumption affects epigenetic changes via histone deacetylation pathways, oligodendrocyte and myelin function, and the oligodendrocyte-related transcription factor, Sox17. Furthermore, a viral vector-assisted knockdown of Sox17 gene expression in the amygdala prevented a gradual increase in alcohol consumption during repeated accesses. Overall, these results suggest that the expression of oligodendrocyte-related genes in the amygdala is sensitive to voluntary alcohol drinking in female mice. These findings suggest potential molecular targets for future therapeutic approaches to prevent the development of AUD, due to repeated excessive alcohol consumption, particularly in women.

Mechanisms of Behavior Change in Substance Use Disorder With and Without Formal Treatment

This article provides a narrative review of studies that examined mechanisms of behavior change in substance use disorder. Several mechanisms have some support, including self-efficacy, craving, protective behavioral strategies, and increasing substance-free rewards, whereas others have minimal support (e.g., motivation, identity). The review provides recommendations for expanding the research agenda for studying mechanisms of change, including designs to manipulate putative change mechanisms, measurement approaches that expand the temporal units of analysis during change efforts, more studies of change outside of treatment, and analytic approaches that move beyond mediation tests. The dominant causal inference approach that focuses on treatment and individuals as change agents could be expanded to include a molar behavioral approach that focuses on patterns of behavior in temporally extended environmental contexts. Molar behavioral approaches may advance understanding of how recovery from substance use disorder is influenced by broader contextual features, community-level variables, and social determinants of health. Expected final online publication date for the Annual Review of Clinical Psychology, Volume 18 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Cognitive training in recently-abstinent individuals with alcohol use disorder improves emotional stroop performance: Evidence from a randomized pilot trial

BACKGROUND

Cognitive training interventions appear capable of improving alcohol-associated neurobehavioral deficits in recently detoxified individuals. However, efficacy remains incompletely characterized in alcohol use disorder (AUD) and available data address only non-affective cognitive outcomes; enhancement of social cognition remains uninvestigated. We utilized a training paradigm in which successfully ignoring emotionally-valent stimuli benefitted task performance. We hypothesized trained individuals would display improvements in an affective inhibitory control task, and that individuals trained with high valence (relative to neutral) stimuli would evince greater improvement.

METHODS

42 recently detoxified inpatients with AUD were assigned to one of three groups (Emotional Training, Neutral Training, or Treatment as Usual [TAU]). Training consisted of two computerized working memory tasks (dual-modality n-back task; attend/ignore task) which included task-irrelevant stimuli (emotional vs. neutral). Post-training performance efficiency (indexing speed-accuracy tradeoffs) in an emotional Stroop task was the outcome of interest.

RESULTS

Significant group by time interactions were detected for emotional Stroop performance, supporting our hypothesis that trained groups would exhibit greater improvement than TAU controls (F[2,39]=8.61, p < .01). Additionally, the emotional training condition appeared to result in greater improvement relative to neutral training (F[1,26]=4.98, p < .01).

CONCLUSION

Results are consistent with current literature suggesting the potential of training to enhance cognitive recovery in early abstinence. Findings inform the development of training protocols, suggesting integration of task-irrelevant distractor stimuli in training may enhance cognitive control outcomes. Further, they expand the relevant domains for application of training approaches, providing novel evidence that among individuals with AUD, training-associated benefits may extend to social cognitive domains.

Memory impairment in alcohol use disorder is associated with regional frontal brain volumes

BACKGROUND

Episodic memory deficits occur in alcohol use disorder (AUD), but their anatomical substrates remain in question. Although persistent memory impairment is classically associated with limbic circuitry disruption, learning and retrieval of new information also relies on frontal systems. Despite AUD vulnerability of frontal lobe integrity, relations between frontal regions and memory processes have been under-appreciated.

METHODS

Participants included 91 AUD (49 with a drug diagnosis history) and 36 controls. Verbal and visual episodic memory scores were age- and education-corrected. Structural magnetic resonance imaging (MRI) data yielded regional frontal lobe (precentral, superior, orbital, middle, inferior, supplemental motor, and medial) and total hippocampal volumes.

RESULTS

AUD were impaired on all memory scores and had smaller precentral frontal and hippocampal volumes than controls. Orbital, superior, and inferior frontal volumes and lifetime alcohol consumption were independent predictors of episodic memory in AUD. Selectivity was established with a double dissociation, where orbital frontal volume predicted verbal but not visual memory, whereas inferior frontal volumes predicted visual but not verbal memory. Further, superior frontal volumes predicted verbal memory in AUD alone, whereas orbital frontal volumes predicted verbal memory in AUD+drug abuse history.

CONCLUSIONS

Selective relations among frontal subregions and episodic memory processes highlight the relevance of extra-limbic regions in mnemonic processes in AUD. Memory deficits resulting from frontal dysfunction, unlike the episodic memory impairment associated with limbic dysfunction, may be more amenable to recovery with cessation or reduction of alcohol misuse and may partially explain the heterogeneity in episodic memory abilities in AUD.

Bmal1 in the striatum influences alcohol intake in a sexually dimorphic manner

Alcohol consumption has been strongly associated with circadian clock gene expression in mammals. Analysis of clock genes revealed a potential role of Bmal1 in the control of alcohol drinking behavior. However, a causal role of Bmal1 and neural pathways through which it may influence alcohol intake have not yet been established. Here we show that selective ablation of Bmal1 (Cre/loxP system) from medium spiny neurons of the striatum induces sexual dimorphic alterations in alcohol consumption in mice, resulting in augmentation of voluntary alcohol intake in males and repression of intake in females. Per2mRNA expression, quantified by qPCR, decreases in the striatum after the deletion of Bmal1. To address the possibility that the effect of striatal Bmal1 deletion on alcohol intake and preference involves changes in the local expression of Per2, voluntary alcohol intake (two-bottle, free-choice paradigm) was studied in mice with a selective ablation of Per2 from medium spiny neurons of the striatum. Striatal ablation of Per2 increases voluntary alcohol intake in males but has no effect in females. Striatal Bmal1 and Per2 expression thus may contribute to the propensity to consume alcohol in a sex -specific manner in mice.

Research Needs for Inpatient Management of Severe Alcohol Withdrawal Syndrome: An Official American Thoracic Society Research Statement

Background: Severe alcohol withdrawal syndrome (SAWS) is highly morbid, costly, and common among hospitalized patients, yet minimal evidence exists to guide inpatient management. Research needs in this field are broad, spanning the translational science spectrum. Goals: This research statement aims to describe what is known about SAWS, identify knowledge gaps, and offer recommendations for research in each domain of the Institute of Medicine T0-T4 continuum to advance the care of hospitalized patients who experience SAWS. Methods: Clinicians and researchers with unique and complementary expertise in basic, clinical, and implementation research related to unhealthy alcohol consumption and alcohol withdrawal were invited to participate in a workshop at the American Thoracic Society 2019 International Conference. The committee was subdivided into four groups on the basis of interest and expertise: T0-T1 (basic science research with translation to humans), T2 (research translating to patients), T3 (research translating to clinical practice), and T4 (research translating to communities). A medical librarian conducted a pragmatic literature search to facilitate this work, and committee members reviewed and supplemented the resulting evidence, identifying key knowledge gaps. Results: The committee identified several investigative opportunities to advance the care of patients with SAWS in each domain of the translational science spectrum. Major themes included 1) the need to investigate non-γ-aminobutyric acid pathways for alcohol withdrawal syndrome treatment; 2) harnessing retrospective and electronic health record data to identify risk factors and create objective severity scoring systems, particularly for acutely ill patients with SAWS; 3) the need for more robust comparative-effectiveness data to identify optimal SAWS treatment strategies; and 4) recommendations to accelerate implementation of effective treatments into practice. Conclusions: The dearth of evidence supporting management decisions for hospitalized patients with SAWS, many of whom require critical care, represents both a call to action and an opportunity for the American Thoracic Society and larger scientific communities to improve care for a vulnerable patient population. This report highlights basic, clinical, and implementation research that diverse experts agree will have the greatest impact on improving care for hospitalized patients with SAWS.