Neurobiology of comorbid post-traumatic stress disorder and alcohol-use disorder

Stress-enhanced ethanol drinking does not increase sensitivity to the effects of a CRF-R1 antagonist on ethanol intake in male and female mice

Research confirms that stress is associated with alcohol drinking and relapse in males and females and that there are sex differences in the alcohol-related adaptations of stress pathways. The predator stress (PS) model of traumatic stress produces an increase in alcohol drinking or self-administration in a subpopulation of rodents, so it is utilized as an animal model of comorbid alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD). Previous work determined that sensitivity to PS-enhanced drinking produced sex differences in proteins related to stress-regulating systems in the medial prefrontal cortex and hippocampus. The present studies examined whether male and female C57BL/6J mice differ in sensitivity to the ability of the corticotropin releasing factor receptor 1 antagonist CP-376395 to decrease PS-enhanced drinking. In control studies, CP-376395 doses of 5, 10, and 20 mg/kg dose-dependently decreased 4-h ethanol drinking. Next, CP-376395 doses of 5 and 10 mg/kg were tested for effects on ethanol drinking in mice with differential sensitivity to PS-enhanced drinking. Subgroups of "Sensitive" and "Resilient" male and female mice were identified based on changes in ethanol intake in an unrestricted-access ethanol-drinking procedure following four exposures to PS (dirty rat bedding). During the first 2 h post-injection of CP-376395, both doses significantly decreased ethanol licks versus vehicle in the females, with no significant interaction between subgroups, whereas the 10 mg/kg dose significantly decreased ethanol licks versus vehicle in the "Resilient" males. Thus, sensitivity to the suppressive effect of CP-376395 on stress-induced ethanol intake was greater in females versus males, whereas sensitivity and resilience to PS-enhanced drinking produced differential sensitivity to the ability of CP-376395 to decrease ethanol drinking only in male mice. Our results argue against greater efficacy of CRF-R1's ability to decrease ethanol intake in subjects with traumatic stress-enhanced ethanol drinking.

Elevated GABAergic neurotransmission prevents chronic intermittent ethanol induced hyperexcitability of intrinsic and extrinsic inputs to the ventral subiculum of female rats

With the recent rise in the rate of alcohol use disorder (AUD) in women, the historical gap between men and women living with this condition is narrowing. While there are many commonalities in how men and women are impacted by AUD, an accumulating body of evidence is revealing sex-dependent adaptations that may require distinct therapeutic approaches. Preclinical rodent studies are beginning to shed light on sex differences in the effects of chronic alcohol exposure on synaptic activity in a number of brain regions. Prior studies from our laboratory revealed that, while withdrawal from chronic intermittent ethanol (CIE), a commonly used model of AUD, increased excitability in the ventral hippocampus (vHC) of male rats, this same treatment had the opposite effect in females. A follow-up study not only expanded on the synaptic mechanisms of these findings in male rats, but also established a CIE-dependent increase in the excitatory-inhibitory (E-I) balance of a glutamatergic projection from the basolateral amygdala to vHC (BLA-vHC). This pathway modulates anxiety-like behavior and could help explain the comorbid occurrence of anxiety disorders in individuals suffering from AUD. The present study sought to conduct a similar analysis of CIE effects on both synaptic mechanisms in the vHC and adaptations in the BLA-vHC pathway of female rats. Our findings indicate that CIE increases the strength of inhibitory neurotransmission in the vHC and that this sex-specific adaptation blocks, or at least delays, the increases in intrinsic vHC excitability and BLA-vHC synaptic transmission observed in males. Our findings establish the BLA-vHC pathway and the vHC as important circuitry to consider for future studies directed at identifying sex-dependent therapeutic approaches to AUD.

Effects of early life stress paired with adolescent alcohol consumption on two-bottle choice alcohol drinking behaviors in mice

Background

In humans, early life stress (ELS) is associated with an increased risk for developing both alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD). We previously used an infant footshock model that produces stress-enhanced fear learning (SEFL) in rats and mice and increases aversion-resistant alcohol drinking in rats to explore this shared predisposition. The goal of the current study was to extend this model of comorbid PTSD and AUD to male and female C57BL/6J mice.

Methods

Acute ELS was induced using 15 footshocks on postnatal day (PND) 17. In adulthood, alcohol drinking behavior was tested in one of three two-bottle choice drinking paradigms. In continuous access, mice were given 24 h access to 5% or 10% ethanol and water for five consecutive drinking sessions each. In limited access drinking in the dark, mice were given 2 h of access to 15% ethanol and water across 15 sessions 3 h into the dark cycle. In intermittent access, mice were presented with 20% ethanol and water Monday, Wednesday, and Friday, for four consecutive weeks. In a fifth week of intermittent access drinking, increasing concentrations of quinine (10 mg/L, 100 mg/L, and 200 mg/L) were added to the ethanol to test aversion-resistant drinking. Intermittent access drinking was tested with and without a period of adolescent drinking (PND 35).

Results

Infant footshock did not alter drinking in the continuous or limited access tasks. Adult consumption and preference were lower in the intermittent access task when adolescent drinking was included and there were ELS-induced differences in consumption of quinine-adulterated ethanol in females.

Conclusions

Our results demonstrate that infant footshock followed by a period of adolescent drinking is a viable model of comorbid PTSD and AUD in rats and mice.

Early life psychosocial stress increases binge-like ethanol consumption and CSF1R inhibition prevents stress-induced alterations in microglia and brain macrophage population density

Early life stress (ELS) has lasting consequences on microglia and brain macrophage function. During ELS, microglia and brain macrophages alter their engagement with synapses leading to changes in neuronal excitability. Further, ELS can induce innate immune memory formation in microglia and brain macrophages resulting in altered responsivity to future environmental stimuli. These alterations can result in lasting adaptations in circuit function and may mediate the relationship between ELS and the risk to develop alcohol use disorder (AUD). Whether microglia and brain macrophages truly mediate this relationship remains elusive. Here, we report: 1) an ELS model, psychosocial stress (PSS), increases binge-like ethanol consumption in early adulthood. 2) Repeated binge-like ethanol consumption increases microglia and brain macrophage population densities across the brain. 3) PSS may elicit innate immune memory formation in microglia and brain macrophages leading to altered population densities following repeated binge-like ethanol consumption. 4) Microglia and brain macrophage inhibition trended towards preventing PSS-evoked changes in binge-like ethanol consumption and normalized microglia and brain macrophage population densities. Therefore, our study suggests that acutely inhibiting microglia and brain macrophage function during periods of early life PSS may prevent innate immune memory formation and assist in reducing the risk to develop AUD.

Highlights

An early life psychosocial stress (PSS) exposure increases ethanol consumptionMicroglial inhibition during PSS trends towards reducing ethanol consumptionBinge ethanol consumption increases microglial count and alters cell proximityEarly life PSS alters microglial responsivity to binge ethanol consumptionMicroglial inhibition may prevent microglial innate immune memory formation.

Effects of early social isolation and adolescent single prolonged stress on anxiety-like behaviors and voluntary ethanol consumption in female Long Evans rats

BACKGROUND

Exposure to stress during childhood and adolescence is a risk factor for alcohol use disorder (AUD) and comorbid conditions, including posttraumatic stress disorder (PTSD). We previously established an adolescent social isolation (SI) model that leads to the emergence of a wide range of behavioral risk factors for AUD, including increased anxiety-like behavior, locomotor activity, and ethanol consumption in male and female rats. Here, we sought to test the hypothesis that SI may increase vulnerability to single prolonged stress (SPS), a rodent model of PTSD.

METHODS

Female Long Evans rats (n = 8/group) were either single-housed or group-housed (GH) (4/cage) on postnatal day 21. One week later, rats underwent testing in the open field test (OFT), elevated plus-maze (EPM), and successive alleys test (SAT). Following initial behavioral testing, a subset of SI/GH rats were exposed to SPS. All rats were then tested on the novelty-suppressed feeding test (NSFT) followed by fear conditioning and home cage two-bottle choice to assess ethanol consumption.

RESULTS

SI significantly increased activity in the OFT and anxiety-like behavior on the SAT, but not the EPM. While SI and SPS alone had no effect on the NSFT, exposure to both stressors significantly increased approach latency. Complex effects of stress history were observed across a 3-day fear conditioning paradigm and no group differences were observed with home cage ethanol consumption, regardless of prior ethanol exposure.

CONCLUSIONS

The results from this study provide novel evidence that SI interacts with SPS in female rats to influence behavior in assays of unconditioned anxiety-like behavior (NSFT) and conditioned fear. Surprisingly, stress exposure had no effect on home cage ethanol consumption. Ultimately, these models provide useful avenues to examine the interaction between stressful experiences, alcohol exposure, biological sex, and the neurobiological adaptations underlying potential risk factors for psychiatric conditions.

The role of recurrent trauma on post-traumatic stress disorder symptoms and substance use among trauma exposed youth

Comorbidity between post-traumatic stress disorder (PTSD) and substance use disorder may be explained by a prospective trauma risk conferred by both conditions. The current study modeled concurrent and prospective associations of trauma, PTSD symptoms, and substance use (SU) behavior among trauma exposed youth (ages 8-20). Clinical interviews assessed trauma exposure, PTSD symptom severity, and SU behavior at baseline and at six- and 12-month follow up study visits (N = 2,069). Structural equation models assessed the associations of trauma, PTSD symptoms, and SU behavior. Lifetime trauma was associated with more severe PTSD symptoms and SU behaviors, whereas trauma exposure during the study was only associated with PTSD symptoms. PTSD symptom severity was prospectively associated with trauma exposure. PTSD symptom severity and SU behavior at follow-up study visits were prospectively associated. These results highlight the dynamic interplay between trauma, PTSD symptoms, and SU behavior during youth, a developmental period during which complex psychiatric presentations can have longstanding consequences for health.

Sex differences in acute early life stress-enhanced fear learning in adult rats

Patients diagnosed with posttraumatic stress disorder (PTSD) present with a spectrum of debilitating anxiety symptoms resulting from exposure to trauma. Women are twice as likely to be diagnosed with anxiety and PTSD compared to men; however, the reason for this vulnerability remains unknown. We conducted four experiments where we first demonstrated a female vulnerability to stress-enhanced fear learning (SEFL) with a moderate, acute early life stress (aELS) exposure (4 footshocks in a single session), compared to a more intense aELS exposure (15 footshocks in a single session) where males and females demonstrated comparable SEFL. Next, we demonstrated that this female vulnerability does not result from differences in footshock reactivity or contextual fear conditioning during the aELS exposure. Finally, using gonadectomy or sham surgeries in adult male and female rats, we showed that circulating levels of gonadal steroid hormones at the time of adult fear conditioning do not explain the female vulnerability to SEFL. Additional research is needed to determine whether this vulnerability can be explained by organizational effects of gonadal steroid hormones or differences in sex chromosome gene expression. Doing so is critical for a better understanding of increased female vulnerability to certain psychiatric diseases.

The Interaction between Education and Sex with Alcohol Consumption during the COVID-19 Pandemic: A Cross-Sectional Analysis of Two Brazilian Cities

This cross-sectional study, carried out between October and December 2020 in two Brazilian cities, aimed to evaluate the joint association of education and sex with habitual and episodic excessive alcohol consumption during the COVID-19 pandemic. Habitual alcohol consumption was defined as drinking any quantity of alcohol at least once per week. Excessive episodic alcohol consumption was defined as the consumption of five or more drinks by men or four or more drinks by women at least once in the last 30 days. Adjusted multivariate logistic regression models were used to analyze associations of education and sex with alcohol consumption. Education was not associated with habitual alcohol consumption and excessive episodic alcohol consumption. However, when evaluating the joint effect between education and sex, it can be seen that men with low education were more likely to habitually consume (OR: 5.85; CI95:2.74-14.84) and abuse alcohol (OR: 4.45; IC95:1.54-12.82) and women with high education were more likely to have habitual (OR: 2.16; IC95:1.18-3.95) and abusive alcohol consumption (OR: 2.00; IC95:1.16-3.43). These findings highlight the modifying effect of sex on the relationship between education and alcohol consumption, such that education influenced alcohol consumption differently between sexes during the pandemic.

Integrative Pharmacology in the Treatment of Substance Use Disorders

The detrimental physical, mental, and socioeconomic effects of substance use disorders (SUDs) have been apparent to the medical community for decades. However, it has become increasingly urgent in recent years to develop novel pharmacotherapies to treat SUDs. Currently, practitioners typically rely on monotherapy. Monotherapy has been shown to be superior to no treatment at all for most substance classes. However, many randomized controlled trials (RCTs) have revealed that monotherapy leads to poorer outcomes when compared with combination treatment in all specialties of medicine. The results of RCTs suggest that monotherapy frequently fails since multiple dysregulated pathways, enzymes, neurotransmitters, and receptors are involved in the pathophysiology of SUDs. As such, research is urgently needed to determine how various neurobiological mechanisms can be targeted by novel combination treatments to create increasingly specific yet exceedingly comprehensive approaches to SUD treatment. This article aims to review the neurobiology that integrates many pathophysiologic mechanisms and discuss integrative pharmacology developments that may ultimately improve clinical outcomes for patients with SUDs. Many neurobiological mechanisms are known to be involved in SUDs including dopaminergic, nicotinic, N-methyl-D-aspartate (NMDA), and kynurenic acid (KYNA) mechanisms. Emerging evidence indicates that KYNA, a tryptophan metabolite, modulates all these major pathophysiologic mechanisms. Therefore, achieving KYNA homeostasis by harmonizing integrative pathophysiology and pharmacology could prove to be a better therapeutic approach for SUDs. We propose KYNA-NMDA-α7nAChRcentric pathophysiology, the "conductor of the orchestra," as a novel approach to treat many SUDs concurrently. KYNA-NMDA-α7nAChR pathophysiology may be the "command center" of neuropsychiatry. To date, extant RCTs have shown equivocal findings across comparison conditions, possibly because investigators targeted single pathophysiologic mechanisms, hit wrong targets in underlying pathophysiologic mechanisms, and tested inadequate monotherapy treatment. We provide examples of potential combination treatments that simultaneously target multiple pathophysiologic mechanisms in addition to KYNA. Kynurenine pathway metabolism demonstrates the greatest potential as a target for neuropsychiatric diseases. The investigational medications with the most evidence include memantine, galantamine, and N-acetylcysteine. Future RCTs are warranted with novel combination treatments for SUDs. Multicenter RCTs with integrative pharmacology offer a promising, potentially fruitful avenue to develop novel therapeutics for the treatment of SUDs.

Traumatic stress-enhanced alcohol drinking: Sex differences and animal model perspectives

Purpose of review

Stress is associated with alcohol drinking, and epidemiological studies document the comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD), with higher comorbid prevalence in females than in males. The aim of this paper is to highlight information related to sex differences in stress-enhanced alcohol drinking from clinical studies and from preclinical studies utilizing an animal model of traumatic stress.

Recent findings

Stress is associated with alcohol drinking and relapse in males and females, but there are sex differences in the alcohol-related adaptation of stress pathways and in the association of different prefrontal regions with stress-induced anxiety. The predator stress model of traumatic stress produced enhanced alcohol drinking in a subgroup of stress-sensitive male and female animals, which could be associated with sex and subgroup differences in stress axis responsivity, behavioral responses to predator odors, and epigenetic mechanisms engaged by traumatic experiences.

Summary

While additional studies in females are necessary, existing clinical and preclinical evidence suggests that biological mechanisms underlying stress-enhanced drinking likely differ between males and females. Thus, effective treatment strategies may differ between the sexes.

Functional Domains of Substance Use and their Implications to Trauma: A Systematic Review of Neuroimaging Studies

Substance use disorder (SUD) is a significant health problem, and trauma exposure is a known risk factor for the escalation of substance use. However, the shared neural mechanisms through which trauma is associated with substance use are still unknown. Therefore, we systematically review neuroimaging studies focusing on three domains that may contribute to the overlapping mechanisms of SUD and trauma-reward salience, negative emotionality, and inhibition. Using PRISMA guidelines, we identified 45 studies utilizing tasks measuring these domains in alcohol, tobacco, and cannabis use groups. Greater reward, lesser regulation of inhibitory processes, and mixed findings of negative emotionality processes in individuals who use substances versus controls were found. Specifically, greater orbitofrontal cortex, ventral tegmental area, striatum, amygdala, and hippocampal activation was found in response to reward-related tasks, and reduced activation was found in the inferior frontal gyrus and hippocampus in response to inhibition-related tasks. Importantly, no studies in trauma-exposed individuals met our review criteria. Future studies examining the role of trauma-related factors are needed, and more studies should explore inhibition- and negative-emotionality domains in individuals who use substances to uncover clinically significant alterations in these domains that place an individual at greater risk for developing a SUD.

Progesterone Attenuates the Stress Response in Individuals with Alcohol Dependence and Post-Traumatic Stress Disorder - A Pilot Study

OBJECTIVE

Evidence from laboratory studies suggests that progesterone may be effective in reducing stress and craving, and may improve cognitive performance in smokers and individuals with cocaine dependence. The objective of this study was to examine if progesterone would attenuate stress-induced craving, anxiety, affect and physiological measures, as well as improve stress-induced cognitive performance (processing speed and selective attention) in individuals diagnosed with alcohol use disorder (AUD) and post traumatic stress disorder (PTSD).

METHODS

This laboratory study included (n = 13) participants who were diagnosed with current AUD and PTSD who were randomly assigned to recive either progesterone (200mg bid) or placebo in identical looking capsules for 3 days. On the fourth day they completed a laboratory session. In the morning of the test session, they received the last dose of medication and completed the rest of the laboratory procedures. The procedures included presentation in random order of personalized trauma and neutral scripts with relaxation in between. Main outcomes included measure of craving, anxiety, affect and cognitive performance.

RESULTS

Consistent with other research, trauma scripts produced significantly greater increases in craving, anxiety and negative affect when compared with neutral scripts. Progesterone significantly reduced stress-induced symptoms of craving, anxiety, fear, anger and sadness but had no effect on positive emotions (joy, relaxation). Progesterone was effective in ameliorating stress-induced decreases in cognitive performance.

CONCLUSIONS

The findings from this study demonstrate that progesterone can be effective in reducing stress-induced craving, anxiety and negative affect in a laboratory setting in individuals with comorbid AUD and PTSD. Interestingly, progesterone also improved cognitive performance. These findings require replication in a larger clinical trial and may have implications for treatment among individuals with AUD and PTSD.This study was registered as NCT02187224, at www.clinicaltrials.gov.

Non-consummatory behavior signals predict aversion-resistant alcohol drinking in head-fixed mice

A key facet of alcohol use disorder is continuing to drink alcohol despite negative consequences (so called "aversion-resistant drinking"). In this study, we sought to assess the degree to which head-fixed mice exhibit aversion-resistant drinking and to leverage behavioral analysis techniques available in head-fixture to relate non-consummatory behaviors to aversion-resistant drinking. We assessed aversion-resistant drinking in head-fixed female and male C57BL/6 J mice. We adulterated 20% (v/v) alcohol with varying concentrations of the bitter tastant quinine to measure the degree to which mice would continue to drink despite this aversive stimulus. We recorded high-resolution video of the mice during head-fixed drinking, tracked body parts with machine vision tools, and analyzed body movements in relation to consumption. Female and male head-fixed mice exhibited heterogenous levels of aversion-resistant drinking. Additionally, non-consummatory behaviors, such as paw movement and snout movement, were related to the intensity of aversion-resistant drinking. These studies demonstrate that head-fixed mice exhibit aversion-resistant drinking and that non-consummatory behaviors can be used to assess perceived aversiveness in this paradigm. Furthermore, these studies lay the groundwork for future experiments that will utilize advanced electrophysiological techniques to record from large populations of neurons during aversion-resistant drinking to understand the neurocomputational processes that drive this clinically relevant behavior. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".

Sexually dimorphic effects of a modified adolescent social isolation paradigm on behavioral risk factors of alcohol use disorder in Long Evans Rats

Early life stress (ELS) is a major risk factor for alcohol use disorder (AUD) and comorbid neuropsychiatric conditions. We previously demonstrated that an adolescent social isolation (aSI) model of ELS significantly increased behavioral risk factors for these disorders (e.g. anxiety-like behaviors, alcohol drinking) in male, but not female rats. Since many neurodevelopmental milestones are accelerated in females, we investigated whether an earlier/shorter isolation window (PND 21-38) would yield comparable phenotypes in both sexes. In two experiments, Long Evans rats were socially isolated (SI) or group-housed (GH) on postnatal day (PND) 21 and locomotion was assessed in the open field test (OFT; PND 30). Experiment 1 also assessed behavior on the elevated plus-maze (EPM) (PND 32). In Experiment 2, all rats were single housed on PND 38 to assess home cage alcohol drinking. Experiment 1 revealed that SI females had increased locomotor activity in the OFT but did not differ from GH subjects on the EPM. The OFT results were replicated in both sexes in Experiment 2 and both male and female SI rats had significantly greater ethanol consumption during an eight day continuous access paradigm. In contrast, during subsequent intermittent two-bottle choice drinking, only SI females displayed greater ethanol intake and preference and increased consumption of a quinine-adulterated alcohol solution. These findings demonstrate that early life social isolation can promote AUD vulnerability-related phenotypes in female rats but that there are profound sex differences in the vulnerability window to this early life stressor. Uncovering the neural mechanisms responsible for these sexually dimorphic differences in sensitivity to ELS may shed light on the biological substrates associated with vulnerability to AUD and comorbid disorders of negative emotion in men and women.

Treating posttraumatic stress disorder and alcohol use disorder comorbidity: Current pharmacological therapies and the future of MDMA-integrated psychotherapy

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) frequently co-occur in patients who have experienced trauma. This comorbidity leads to a vicious cycle where PTSD symptoms beget heavy drinking and vice versa. There are no FDA-approved medications to treat PTSD-AUD; therefore, individuals suffering from this comorbidity are treated with medication approved to treat the disorders separately or with off-label pharmacological interventions. However, these medications are limited in their efficacy for treating PTSD-AUD comorbidity. Emerging research on the nonclassical psychedelic drug 3,4-methylenedioxymethamphetamine (MDMA) suggests that it may be an effective drug used in conjunction with psychotherapy. The following reviews the current research for clinical pharmacotherapies, as well as MDMA-integrative psychotherapy as they pertain to PTSD and AUD in isolation and co-occurrence. Future directions for the role of psychedelic-integrative therapy for the treatment of this comorbidity are discussed.

Non-Consummatory Behavior Signals Predict Aversion-Resistant Alcohol Drinking in Head-Fixed Mice

A key facet of alcohol use disorder is continuing to drink alcohol despite negative consequences (so called "aversion-resistant drinking"). In this study, we sought to assess the degree to which head-fixed mice exhibit aversion-resistant drinking and to leverage behavioral analysis techniques available in head-fixture to relate non-consummatory behaviors to aversion-resistant drinking. We assessed aversion-resistant drinking in head-fixed female and male C57BL/6J mice. We adulterated 20% (v/v) alcohol with varying concentrations of the bitter tastant quinine to measure the degree to which mice would continue to drink despite this aversive stimulus. We recorded high-resolution video of the mice during head-fixed drinking, tracked body parts with machine vision tools, and analyzed body movements in relation to consumption. Female and male head-fixed mice exhibited heterogenous levels of aversion-resistant drinking. Additionally, non-consummatory behaviors, such as paw movement and snout movement, were related to the intensity of aversion-resistant drinking. These studies demonstrate that head-fixed mice exhibit aversion-resistant drinking and that non-consummatory behaviors can be used to assess perceived aversiveness in this paradigm. Furthermore, these studies lay the groundwork for future experiments that will utilize advanced electrophysiological techniques to record from large populations of neurons during aversion-resistant drinking to understand the neurocomputational processes that drive this clinically relevant behavior.

Stress and gonadal steroid influences on alcohol drinking and withdrawal, with focus on animal models in females

Sexually dimorphic effects of alcohol, following binge drinking, chronic intoxication, and withdrawal, are documented at the level of the transcriptome and in behavioral and physiological responses. The purpose of the current review is to update and to expand upon contributions of the endocrine system to alcohol drinking and withdrawal in females, with a focus on animal models. Steroids important in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axes, the reciprocal interactions between these axes, the effects of chronic alcohol use on steroid levels, and the genomic and rapid membrane-associated effects of steroids and neurosteroids in models of alcohol drinking and withdrawal are described. Importantly, comparison between males and females highlight some divergent effects of sex- and stress-steroids on alcohol drinking- and withdrawal-related behaviors, and the distinct differences in response emphasize the importance of considering sex in the development of novel pharmacotherapies for the treatment of alcohol use disorder.

Oxytocin Reduces Sensitized Stress-Induced Alcohol Relapse in a Model of Posttraumatic Stress Disorder and Alcohol Use Disorder Comorbidity

BACKGROUND

There is high comorbidity of posttraumatic stress disorder (PTSD) and alcohol use disorder with few effective treatment options. Animal models of PTSD have shown increases in alcohol drinking, but effects of stress history on subsequent vulnerability to alcohol relapse have not been examined. Here we present a mouse model of PTSD involving chronic multimodal stress exposure that resulted in long-lasting sensitization to stress-induced alcohol relapse, and this sensitized stress response was blocked by oxytocin (OT) administration.

METHODS

Male and female mice trained to self-administer alcohol were exposed to predator odor (TMT) + yohimbine over 5 consecutive days or left undisturbed. After reestablishing stable alcohol responding/intake, mice were tested under extinction conditions, and then all mice were exposed to TMT or context cues previously associated with TMT before a reinstatement test session. Separate studies examined messenger RNA expression of Oxt and Oxtr in hypothalamus following chronic stress exposure. A final study examined the effects of systemic administration of OT on stress-induced alcohol relapse in mice with and without a history of chronic stress experience.

RESULTS

Chronic stress exposure produced long-lasting sensitization to subsequent stress-induced alcohol relapse that also generalized to stress-related context cues and transcriptional changes in hypothalamic OT system. OT injected before the reinstatement test session completely blocked the sensitized stress-induced alcohol relapse effect.

CONCLUSIONS

Collectively, these results provide support for the therapeutic potential of OT, along with highlighting the value of utilizing this model in evaluating other pharmacological interventions for treatment of PTSD/alcohol use disorder comorbidity.

IL-18 Signaling in the Rat Central Amygdala Is Disrupted in a Comorbid Model of Post-Traumatic Stress and Alcohol Use Disorder

Alcohol use disorder (AUD) and anxiety disorders are frequently comorbid and share dysregulated neuroimmune-related pathways. Here, we used our established rat model of comorbid post-traumatic stress disorder (PTSD)/AUD to characterize the interleukin 18 (IL-18) system in the central amygdala (CeA). Male and female rats underwent novel (NOV) and familiar (FAM) shock stress, or no stress (unstressed controls; CTL) followed by voluntary alcohol drinking and PTSD-related behaviors, then all received renewed alcohol access prior to the experiments. In situ hybridization revealed that the number of CeA positive cells for Il18 mRNA increased, while for Il18bp decreased in both male and female FAM stressed rats versus CTL. No changes were observed in Il18r1 expression across groups. Ex vivo electrophysiology showed that IL-18 reduced GABAA-mediated miniature inhibitory postsynaptic currents (mIPSCs) frequencies in CTL, suggesting reduced CeA GABA release, regardless of sex. Notably, this presynaptic effect of IL-18 was lost in both NOV and FAM males, while it persisted in NOV and FAM females. IL-18 decreased mIPSC amplitude in CTL female rats, suggesting postsynaptic effects. Overall, our results suggest that stress in rats with alcohol access impacts CeA IL-18-system expression and, in sex-related fashion, IL-18's modulatory function at GABA synapses.

Post-traumatic stress disorder burden among female Syrian war refugees is associated with dysmenorrhea severity but not with the analgesics

Dysmenorrhea association with post-traumatic stress disorder (PTSD) has not been studied in refugees. We aimed to examine the associations between dysmenorrhea severity, dysmenorrhea analgesics self-medications, and PTSD in a cohort of Syrian war refugees residing in Jordan.<br /> This is a cross-sectional study based on predetermined inclusion criteria held at Caritas primary care centers in Jordanian districts between September and October 2022. The participants’ demographics and analgesic self-medication type were recorded through a structured questionnaire. The dysmenorrhea severity was measured by (working ability, location, intensity, days of pain, and dysmenorrhea) WaLiDD scale, PTSD was measured by Davidson trauma scale (DTS)-DSM-IV.<br /> Data from 347 Syrian female war refugees were analyzed. The multivariate analysis showed that dysmenorrhea severity demonstrated significantly higher estimates for PTSD (10.48 [6.72-14.23], p=0.001), however, the analgesic type was not associated with PTSD burden.<br /> In conclusion, dysmenorrhea severity, but not self-medication, was associated with a higher PTSD burden.

Molecular Toxicology and Pathophysiology of Comorbid Alcohol Use Disorder and Post-Traumatic Stress Disorder Associated with Traumatic Brain Injury

The increasing comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) associated with traumatic brain injury (TBI) is a serious medical, economic, and social issue. However, the molecular toxicology and pathophysiological mechanisms of comorbid AUD and PTSD are not well understood and the identification of the comorbidity state markers is significantly challenging. This review summarizes the main characteristics of comorbidity between AUD and PTSD (AUD/PTSD) and highlights the significance of a comprehensive understanding of the molecular toxicology and pathophysiological mechanisms of AUD/PTSD, particularly following TBI, with a focus on the role of metabolomics, inflammation, neuroendocrine, signal transduction pathways, and genetic regulation. Instead of a separate disease state, a comprehensive examination of comorbid AUD and PTSD is emphasized by considering additive and synergistic interactions between the two diseases. Finally, we propose several hypotheses of molecular mechanisms for AUD/PTSD and discuss potential future research directions that may provide new insights and translational application opportunities.

Chemogenetic inhibition of a monosynaptic projection from the basolateral amygdala to the ventral hippocampus selectively reduces appetitive, but not consummatory, alcohol drinking-related behaviours

Alcohol use disorder (AUD) and anxiety/stressor disorders frequently co-occur and this dual diagnosis represents a major health and economic problem worldwide. The basolateral amygdala (BLA) is a key brain region that is known to contribute to the aetiology of both disorders. Although many studies have implicated BLA hyperexcitability in the pathogenesis of AUD and comorbid conditions, relatively little is known about the specific efferent projections from this brain region that contribute to these disorders. Recent optogenetic studies have shown that the BLA sends a strong monosynaptic excitatory projection to the ventral hippocampus (vHC) and that this circuit modulates anxiety- and fear-related behaviours. However, it is not known if this pathway influences alcohol drinking-related behaviours. Here, we employed a rodent operant self-administration regimen that procedurally separates appetitive (e.g. seeking) and consummatory (e.g., drinking) behaviours, chemogenetics and brain region-specific microinjections, to determine if BLA-vHC circuitry influences alcohol and sucrose drinking-related measures. We first confirmed prior optogenetic findings that silencing this circuit reduced anxiety-like behaviours on the elevated plus maze. We then demonstrated that inhibiting the BLA-vHC pathway significantly reduced appetitive drinking-related behaviours for both alcohol and sucrose while having no effect on consummatory measures. Taken together, these findings provide the first indication that the BLA-vHC circuit may regulate appetitive reward seeking directed at alcohol and natural rewards and add to a growing body of evidence suggesting that dysregulation of this pathway may contribute to the pathophysiology of AUD and anxiety/stressor-related disorders.

Psychobiotic interventions attenuate chronic alcohol use-mediated exacerbation of posttraumatic stress disorder in rats: the role of gut-liver axis response

OBJECTIVES

The incidence of co-occurring alcohol-use disorder (AUD) and post-traumatic stress disorder (PTSD) is high, and the presence of one disorder aggravates the severity of the other. Emerging evidence shows the neuroprotective and anti-inflammation functions of psychobiotics. Hence, the study explored the effects of probiotics and synbiotic inulin on the gut- and liver-oxidative and inflammatory biomarkers in chronic alcohol exacerbation of PTSD symptoms in rats.

METHODS

Young adult rats were administered 10% ethanol in a two-bottle choice test for six weeks and were subjected to single prolonged stress. Probiotics and synbiotic intervention followed this. Markers of oxido-inflammatory stress, liver functions, intestinal (faecal) metabolites, occludin expression, and histopathology of the ileum and liver were evaluated.

RESULTS

Chronic alcohol drinking and PTSD increased oxido-inflammatory stress, markers of hepatic damage, and reduced faecal metabolites, which were attenuated by probiotic and synbiotic interventions. Furthermore, reduced immunoexpression of gut and liver occludin, with loss of barrier integrity, viable hepatocytes, congestive portal area, and shortened villi and crypt depth, were observed. Probiotic and synbiotic interventions mitigated these effects.

CONCLUSIONS

The study demonstrates that psychobiotics mitigate the detrimental effects of co-occurring chronic alcohol intake in the context of PTSD.

Posttraumatic stress as a moderator of the association between HPA-axis functioning and alcohol use disorder among a community sample of women currently experiencing intimate partner violence

Women experiencing intimate partner violence (IPV) experience a heightened prevalence of alcohol use disorder (AUD). Hypothalamic-pituitary-adrenal (HPA)-axis functioning has been associated with increased risk for AUD in other populations, including individuals with posttraumatic stress disorder (PTSD) symptoms. The goal of the present study was to determine whether PTSD symptom severity exacerbates the relationship between HPA-axis functioning and AUD. Participants were 151 community women who had experienced physical or sexual IPV in the past 30 days by their current male partners and used any amount of alcohol or drugs. A two-phase emotion induction protocol was utilized: Neutral mood induction followed by randomly assigned negative, positive, or neutral emotion induction. Saliva cortisol samples were obtained immediately following the neutral mood induction (baseline HPA-axis functioning), 20 min following the individualized emotion induction script (HPA-axis reactivity), and 40 min post the emotionally evocative cue (HPA-axis recovery). Findings revealed that PTSD symptom severity moderated the relations between baseline HPA-axis functioning and HPA-axis recovery and log odds of meeting criteria for AUD. Specifically, baseline HPA-axis functioning was positively associated with log odds of meeting criteria for AUD at high (but not low) PTSD symptom severity, whereas HPA-axis recovery was negatively associated with log odds of meeting criteria for AUD at high (but not low) PTSD symptom severity. Results contribute to our understanding of the biological processes involved in the etiology and maintenance of AUD among women experiencing IPV-specifically the prominent role of PTSD symptom severity. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Early intervention using written exposure therapy for PTSD and AUD symptoms following sexual assault: Description of design and methodology

The co-occurrence of posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) is common following sexual assault and associated with more severe symptomology and increased likelihood of sexual revictimization. Integrated interventions aimed at reducing PTSD and AUD symptoms following recent sexual assault are needed and should address barriers to care and early treatment termination. The proposed study will test a novel, brief (5 to 7 sessions) intervention that integrates Written Exposure Therapy for PTSD and Cognitive Behavioral Therapy for AUD, and is initiated within the first six weeks post-assault. In Phase 1, qualitative analysis of content gathered during focus groups with treatment providers will be conducted to inform intervention development. In Phase 2, a proof-of-concept pilot study (n = 10) of the intervention, Substance Use Skills Training and Exposure Post-Sexual Assault (STEPS), will be conducted. In Phase 3, a pilot randomized controlled trial (RCT) among 54 recent sexual assault survivors will be implemented using the updated manualized STEPS intervention to evaluate feasibility and preliminary efficacy in reducing PTSD and AUD symptoms. Ecological momentary assessments will be used to assess daily alcohol use, craving, affect, intrusions and avoidance. The effects of STEPS on commonly associated symptoms (e.g., depression, substance use) will be examined. The proposed study has the potential to make a significant public health impact by advancing knowledge on the link between sexual assault and co-occurring PTSD and AUD and informing early intervention efforts for this high-risk population.

Resting-state connectivity subtype of comorbid PTSD and alcohol use disorder moderates improvement from integrated prolonged exposure therapy in Veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly comorbid and are associated with significant functional impairment and inconsistent treatment outcomes. Data-driven subtyping of this clinically heterogeneous patient population and the associated underlying neural mechanisms are highly needed to identify who will benefit from psychotherapy.

METHODS

In 53 comorbid PTSD/AUD patients, resting-state functional magnetic resonance imaging was collected prior to undergoing individual psychotherapy. We used a data-driven approach to subgroup patients based on directed connectivity profiles. Connectivity subgroups were compared on clinical measures of PTSD severity and heavy alcohol use collected at pre- and post-treatment.

RESULTS

We identified a subgroup of patients associated with improvement in PTSD symptoms from integrated-prolonged exposure therapy. This subgroup was characterized by lower insula to inferior parietal cortex (IPC) connectivity, higher pregenual anterior cingulate cortex (pgACC) to posterior midcingulate cortex connectivity and a unique pgACC to IPC path. We did not observe any connectivity subgroup that uniquely benefited from integrated-coping skills or subgroups associated with change in alcohol consumption.

CONCLUSIONS

Data-driven approaches to characterize PTSD/AUD subtypes have the potential to identify brain network profiles that are implicated in the benefit from psychological interventions - setting the stage for future research that targets these brain circuit communication patterns to boost treatment efficacy.

Comorbidity of Post-Traumatic Stress Disorder and Alcohol Use Disorder: Animal Models and Associated Neurocircuitry

Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are prevalent neuropsychiatric disorders and frequently co-occur concomitantly. Individuals suffering from this dual diagnosis often exhibit increased symptom severity and poorer treatment outcomes than those with only one of these diseases. Lacking standard preclinical models limited the exploration of neurobiological mechanisms underlying PTSD and AUD comorbidity. In this review, we summarize well-accepted preclinical model paradigms and criteria for developing successful models of comorbidity. We also outline how PTSD and AUD affect each other bidirectionally in the nervous nuclei have been heatedly discussed recently. We hope to provide potential recommendations for future research.

Chronic ethanol consumption exacerbates future stress-enhanced fear learning, an effect mediated by dorsal hippocampal astrocytes

BACKGROUND

Alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) are highly comorbid, yet there is a lack of preclinical research investigating how prior ethanol (EtOH) dependence influences the development of a PTSD-like phenotype. Furthermore, the neuroimmune system has been implicated in the development of both AUD and PTSD, but the extent of glial involvement in this context remains unclear. A rodent model was developed to address this gap in the literature.

METHODS

We used a 15-day exposure to the 5% w/v EtOH low-fat Lieber-DeCarli liquid diet in combination with the stress-enhanced fear learning (SEFL) paradigm to investigate the effects of chronic EtOH consumption on the development of a PTSD-like phenotype. Next, we used a reverse transcription quantitative real-time polymerase chain reaction to quantify mRNA expression of glial cell markers GFAP (astrocytes) and CD68 (microglia) following severe footshock stress in EtOH-withdrawn rats. Finally, we tested the functional contribution of dorsal hippocampal (DH) astrocytes in the development of SEFL in EtOH-dependent rats using astrocyte-specific Gi designer receptors exclusively activated by designer drugs (Gi -DREADD).

RESULTS

Results demonstrate that chronic EtOH consumption and withdrawal exacerbate future SEFL. Additionally, we found significantly increased GFAP mRNA expression in the dorsal and ventral hippocampus and amygdalar complex following the severe stressor in EtOH-withdrawn animals. Finally, the stimulation of the astroglial Gi -DREADD during EtOH withdrawal prevented the EtOH-induced enhancement of SEFL.

CONCLUSIONS

Collectively, results indicate that prior EtOH dependence and withdrawal combined with a severe stressor potentiate future enhanced fear learning. Furthermore, DH astrocytes significantly contribute to this change in behavior. Overall, these studies provide insight into the comorbidity of AUD and PTSD and the potential neurobiological mechanisms behind increased susceptibility to a PTSD-like phenotype in individuals with AUD.

Trauma Cue-Elicited Alcohol Craving as a Function of Adult Versus Childhood-Onset Interpersonal Traumatic Events in Young Adult Drinkers

OBJECTIVE

Childhood trauma may influence risk for alcohol use disorder and posttraumatic stress disorder through negative and positive reinforcement drinking. Laboratory studies evaluating childhood trauma in relation to these phenotypes are limited.

METHOD

This study examined the influence of childhood index traumas on responses to trauma and alcohol cues among 184 college students (50.0% female) endorsing lifetime interpersonal trauma and current weekly alcohol use. Participants' subjective alcohol craving and distress were measured in response to four narrative (trauma vs. neutral) and beverage (alcohol vs. water) cue combinations.

RESULTS

Forward-fitted linear mixed-effects models indicated main effects of childhood index traumas on distress (β= 6.151, p = .001) and craving (β = 0.656, p = .023), wherein individuals with childhood index traumas showed evidence of elevated levels of distress and craving. Childhood index trauma interacted with the narrative cue to predict distress (β = -10.764, p = .002), wherein individuals with childhood index traumas showed greater levels of distress to the neutral cue, and individuals with adult index traumas showed greater levels of distress to the trauma cue. Childhood index trauma interacted with the beverage cue to predict craving (β = -0.599, p = .011), wherein childhood index traumas were associated with greater levels of craving to neutral cues. Childhood index trauma did not significantly interact with the beverage cue to predict distress or the narrative cue to predict craving (ps > .05).

CONCLUSIONS

Childhood trauma may be more relevant to positive rather than negative reinforcement aspects of alcohol use disorder during young adulthood.

Excessive alcohol consumption after exposure to two types of chronic social stress: intermittent episodes vs. continuous exposure in C57BL/6J mice with a history of drinking

RATIONALE

The attraction to alcohol can be greatly increased when it is consumed in a social context. While pro-social interactions can potentiate voluntary alcohol drinking under some conditions, aversive social experience (i.e., social stress) can similarly intensify alcohol consumption.

OBJECTIVE

We sought to determine how exposure to different types of chronic social stress (i.e., intermittent episodes of social defeat or continuous social stress) influences alcohol consumption and the reinforcing effects of alcohol in mice with a history of drinking.

METHODS

Separate cohorts of male C57BL/6J mice were exposed to either 10 days of continuous or intermittent social defeat stress. In experiment 1, mice were assigned to 20% w/v alcohol consumption in a two-bottle choice protocol both prior to and after exposure to social defeat stress. In a second experiment, mice engaged in an operant response sequence to gain access to alcohol wherein completion of a fixed interval (FI; 5 min) schedule was reinforced with continuous access to alcohol (fixed ratio; FR1) for up to 1.8 g/kg. Alcohol-reinforced responding and subsequent alcohol consumption were assessed daily for 4 weeks prior to the 10-day social stress exposure and for 6-week post-stress. Machine learning was implemented to standardize the analysis of defeat behaviors exhibited by the intruder mouse during confrontation with an attacking resident.

RESULTS

In mice with a prior history of alcohol drinking, intermittent episodes of social defeat stress produced a significant increase in 20% EtOH consumption in preference over concurrently available water. This increased intake persisted for at least 6 weeks after the final social stress experience. Intermittently stressed mice also accelerated their anticipatory responding during the fixed interval component of the operant response chain that was reinforced by alcohol. Neither unstressed controls nor mice exposed to continuous social stress exhibited significant increases in alcohol consumption and alcohol reinforcement.

DISCUSSION

Episodic social defeat stress promotes the seeking and consumption of alcohol, extending earlier work to alcohol-experienced mice. We hypothesize that intermittent access to alcohol and intermittent episodes of social stress are additive and share common sensitizing neural mechanisms that engender excessive alcohol consumption.

Elucidating the Neurobiologic Etiology of Comorbid PTSD and Substance Use Disorders

Early childhood maltreatment and other traumatic event experiences ("trauma") are common among youth, including those with substance use problems including substance use disorders (SUD). Particularly, interpersonal violence is associated with high rates of comorbidity between posttraumatic stress disorder (PTSD) and SUD, and these comorbid disorders exhibit high levels of overlapping symptomatology. Theoretical models proposed to explain the bidirectional relationship between PTSD and SUD include the self-medication hypothesis and susceptibility hypothesis. In this article, we explore neurobiologic changes associated with trauma, PTSD, and SUD that underly dysregulated stress response. Examining lessons learned from recent translational and clinical research, we propose that further elucidating the neurobiologic etiology of comorbid PTSD and SUD will require a collaborative, interdisciplinary approach, including the integration of preclinical and clinical studies, exploration of biologic markers in clinical studies, and accumulation of larger studies and longitudinal studies with the power to study PTSD and SUD. Such research can transform the field and ultimately reduce high rates and costly impairment of co-occurring PTSD and SUD across the lifespan.

Hippocampal fear engrams modulate ethanol-induced maladaptive contextual generalization in mice

The compounding symptomatology of alcohol use disorder (AUD) and co-occurring mental health disorders gives rise to interactions of maladaptive neurobiological processes, the etiology of which are elusive. Here, we devised an optogenetic strategy aimed at rescuing maladaptive fear processing in male c57BL/6 mice that underwent a chronic ethanol administration and forced abstinence paradigm. In the first experiment, we confirmed that fear acquisition and maladaptive contextual generalization was potentiated in ethanol-exposed mice during fear conditioning and exposure to a novel environment, respectively. In the second experiment, using an activity-dependent tet-tag system, we labeled the neural ensemble selectively activated by contextual fear conditioning in the dorsal hippocampus with an inhibitory opsin to attenuate behavioral dysfunctions resulting from ethanol exposure. We found that acute optogenetic perturbations during exposure to a novel environment suppressed maladaptive generalization in ethanol-exposed mice. These results provide further evidence for a crucial link between ethanol exposure and impaired fear memory processing by providing cellular and behavioral insights into the neural circuitry underlying AUD and maladaptive fear processing.

Sensitivity and Resilience to Predator Stress-Enhanced Ethanol Drinking Is Associated With Sex-Dependent Differences in Stress-Regulating Systems

Stress can increase ethanol drinking, and evidence confirms an association between post-traumatic stress disorder (PTSD) and the development of alcohol use disorder (AUD). Exposure to predator odor is considered a traumatic stressor, and predator stress (PS) has been used extensively as an animal model of PTSD. Our prior work determined that repeated exposure to intermittent PS significantly increased anxiety-related behavior, corticosterone levels, and neuronal activation in the hippocampus and prefrontal cortex in naïve male and female C57BL/6J mice. Intermittent PS exposure also increased subsequent ethanol drinking in a subgroup of animals, with heterogeneity of responses as seen with comorbid PTSD and AUD. The present studies built upon this prior work and began to characterize “sensitivity” and “resilience” to PS-enhanced drinking. Ethanol drinking was measured during baseline, intermittent PS exposure, and post-stress; mice were euthanized after 24-h abstinence. Calculation of median and interquartile ranges identified “sensitive” (>20% increase in drinking over baseline) and “resilient” (no change or decrease in drinking from baseline) subgroups. Intermittent PS significantly increased subsequent ethanol intake in 24% of male (↑60%) and in 20% of female (↑71%) C57BL/6J mice in the “sensitive” subgroup. Plasma corticosterone levels were increased significantly after PS in both sexes, but levels were lower in the “sensitive” vs. “resilient” subgroups. In representative mice from “sensitive” and “resilient” subgroups, prefrontal cortex and hippocampus were analyzed by Western Blotting for levels of corticotropin releasing factor (CRF) receptor 1, CRF receptor 2, CRF binding protein, and glucocorticoid receptor, vs. separate naïve age-matched mice. In prefrontal cortex, CRF receptor 1, CRF receptor 2, CRF binding protein, and glucocorticoid receptor levels were significantly higher in “sensitive” vs. naïve and “resilient” mice only in females. In hippocampus, CRF receptor 1, CRF receptor 2 and glucocorticoid receptor levels were significantly lower in “resilient” vs. naïve and “sensitive” mice across both sexes. These results indicate that sex strongly influences the effects of ethanol drinking and stress on proteins regulating stress and anxiety responses. They further suggest that targeting the CRF system and glucocorticoid receptors in AUD needs to consider the comorbidity of PTSD with AUD and sex of treated individuals.

Comorbid alcohol use and post-traumatic stress disorders: Pharmacotherapy with aldehyde dehydrogenase 2 inhibitors versus current agents

The increased risk of alcohol use disorder (AUD) in individuals with post-traumatic stress disorder (PTSD) is well-documented. Compared to individuals with PTSD or AUD alone, those with co-existing PTSD and AUD exhibit greater symptom severity, poorer quality of life, and poorer treatment outcomes. Although the treatment of comorbid AUD is vital for the effective management of PTSD, there is a lack of evidence on how to best treat comorbid PTSD and AUD, and currently, there are no FDA-approved treatments for the PTSD-AUD comorbidity. The objective of this manuscript is to review the evidence of a promising target for treating the AUD-PTSD comorbidity. First, we summarize the epidemiological evidence and review the completed clinical studies that have tested pharmacotherapeutic approaches for co-existing AUD and PTSD. Next, we summarize the shared pathological factors between AUD and PTSD. We conclude by providing a rationale for selectively inhibiting aldehyde dehydrogenase-2 as a potential target to treat comorbid AUD in persons with PTSD.

An Association Between Psychological Childbirth Trauma and Hazardous Alcohol Use

Hazardous alcohol use is increasing amongst some groups of women, yet little is known about the underlying reasons or gender-specific influences. The purpose of this study was to explore the association between psychological childbirth trauma and women’s hazardous alcohol use. We aimed to identify predictors of hazardous alcohol use given childbirth-related trauma, other life trauma (combat, natural disasters, physical or sexual assault, experiences threatening loss of life or loss of loved ones) and coping motives for drinking, whilst controlling for age, socio-economic status, negative affect and other drinking motives (enhancement and social motives). Australian data from the Why Women Drink survey (N = 301) was analysed. Women who experienced childbirth as traumatic scored higher overall for hazardous drinking and endorsed coping reasons more strongly than those who did not. Analyses of individual differences affecting hazardous drinking revealed coping reasons, rather than trauma itself, as the strongest predictor in a regression model. Other significant predictors included socio-economic status, enhancement of positive emotions and, marginally, negative affect. Findings identified a link between traumatic childbirth and hazardous drinking as a coping strategy. Prospective research is required to characterise predisposing and perpetuating vulnerabilities determining maladaptive coping after traumatic childbirth, and to inform effective interventions.

Friend of the Devil: Negative Social Influences Driving Substance Use Disorders

Substance use disorders in humans have significant social influences, both positive and negative. While prosocial behaviors promote group cooperation and are naturally rewarding, distressing social encounters, such as aggression exhibited by a conspecific, are aversive and can enhance the sensitivity to rewarding substances, promote the acquisition of drug-taking, and reinstate drug-seeking. On the other hand, withdrawal and prolonged abstinence from drugs of abuse can promote social avoidance and suppress social motivation, accentuating drug cravings and facilitating relapse. Understanding how complex social states and experiences modulate drug-seeking behaviors as well as the underlying circuit dynamics, such as those interacting with mesolimbic reward systems, will greatly facilitate progress on understanding triggers of drug use, drug relapse and the chronicity of substance use disorders. Here we discuss some of the common circuit mechanisms underlying social and addictive behaviors that may underlie their antagonistic functions. We also highlight key neurochemicals involved in social influences over addiction that are frequently identified in comorbid psychiatric conditions. Finally, we integrate these data with recent findings on (±)3,4-methylenedioxymethamphetamine (MDMA) that suggest functional segregation and convergence of social and reward circuits that may be relevant to substance use disorder treatment through the competitive nature of these two types of reward. More studies focused on the relationship between social behavior and addictive behavior we hope will spur the development of treatment strategies aimed at breaking vicious addiction cycles.

Effects of oxytocin administration on fear-potentiated acoustic startle in co-occurring PTSD and alcohol use disorder: A randomized clinical trial

Co-occurring posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) is common and particularly associated with elevation of hyperarousal compared to PTSD alone. Treatment options are limited. Oxytocin regulates physiological stress response. Intranasal oxytocin administration has demonstrated potential in reducing symptoms of both PTSD and AUD. This study addresses a gap in the literature by investigating effects of intranasal oxytocin on startle reactivity, an important potential marker of both PTSD and AUD symptomatology. This is a randomized, double-blind, placebo-controlled, within- and between-participant, crossover, dose-ranging study examining the effects of a single administration of oxytocin 20 IU versus 40 IU versus placebo on psychophysiological responses to a common laboratory fear-potentiated acoustic startle paradigm in participants with PTSD-AUD (n = 47) and controls (n = 37) under three different levels of threat. Contrary to our hypothesis, for the PTSD-AUD group, oxytocin 20 IU had no effect on startle reactivity, while oxytocin 40 IU increased measures of startle reactivity. Additionally, for PTSD-AUD only, ambiguous versus low threat was associated with an elevated skin conductance response. For controls only, oxytocin 20 IU versus placebo was associated with reduced startle reactivity.

Linking Ethanol-Addictive Behaviors With Brain Catecholamines: Release Pattern Matters

Using a variety of animal models that simulate key features of the alcohol use disorder (AUD), remarkable progress has been made in identifying neurochemical targets that may contribute to the development of alcohol addiction. In this search, the dopamine (DA) and norepinephrine (NE) systems have been long thought to play a leading role in comparison with other brain systems. However, just recent development and application of optogenetic approaches into the alcohol research field provided opportunity to identify neuronal circuits and specific patterns of neurotransmission that govern the key components of ethanol-addictive behaviors. This critical review summarizes earlier findings, which initially disclosed catecholamine substrates of ethanol actions in the brain and shows how the latest methodologies help us to reveal the significance of DA and NE release changes. Specifically, we focused on recent optogenetic investigations aimed to reveal cause-effect relationships between ethanol-drinking (seeking and taking) behaviors and catecholamine dynamics in distinct brain pathways. These studies gain the knowledge that is needed for the better understanding addiction mechanisms and, therefore, for development of more effective AUD treatments. Based on the reviewed findings, new messages for researches were indicated, which may have broad applications beyond the field of alcohol addiction.

Neurobiological Bases of Alcohol Consumption After Social Stress

The urge to seek and consume excessive alcohol is intensified by prior experiences with social stress, and this cascade can be modeled under systematically controlled laboratory conditions in rodents and non-human primates. Adaptive coping with intermittent episodes of social defeat stress often transitions to maladaptive responses to traumatic continuous stress, and alcohol consumption may become part of coping responses. At the circuit level, the neural pathways subserving stress coping intersect with those for alcohol consumption. Increasingly discrete regions and connections within the prefrontal cortex, the ventral and dorsal striatum, thalamic and hypothalamic nuclei, tegmental areas as well as brain stem structures begin to be identified as critical for reacting to and coping with social stress while seeking and consuming alcohol. Several candidate molecules that modulate signals within these neural connections have been targeted in order to reduce excessive drinking and relapse. In spite of some early clinical failures, neuropeptides such as CRF, opioids, or oxytocin continue to be examined for their role in attenuating stress-escalated drinking. Recent work has focused on neural sites of action for peptides and steroids, most likely in neuroinflammatory processes as a result of interactive effects of episodic social stress and excessive alcohol seeking and drinking.

Reciprocal midbrain-extended amygdala circuit activity in preclinical models of alcohol use and misuse

Alcohol dependence is characterized by a shift in motivation to consume alcohol from positive reinforcement (i.e., increased likelihood of future alcohol drinking based on its rewarding effects) to negative reinforcement (i.e., increased likelihood of future alcohol drinking based on alcohol-induced reductions in negative affective symptoms, including but not limited to those experienced during alcohol withdrawal). The neural adaptations that occur during this transition are not entirely understood. Mesolimbic reinforcement circuitry (i.e., ventral tegmental area [VTA] neurons) is activated during early stages of alcohol use, and may be involved in the recruitment of brain stress circuitry (i.e., extended amygdala) during the transition to alcohol dependence, after chronic periods of high-dose alcohol exposure. Here, we review the literature regarding the role of canonical brain reinforcement (VTA) and brain stress (extended amygdala) systems, and the connections between them, in acute, sub-chronic, and chronic alcohol response. Particular emphasis is placed on preclinical models of alcohol use.

FACTORS CONTRIBUTING TO THE ESCALATION OF ALCOHOL CONSUMPTION

Understanding factors that contribute to the escalation of alcohol consumption is key to understanding how an individual transitions from non/social drinking to AUD and to providing better treatment. In this review, we discuss how the way ethanol is consumed as well as individual and environmental factors contribute to the escalation of ethanol consumption from intermittent low levels to consistently high levels. Moreover, we discuss how these factors are modelled in animals. It is clear a vast array of complex, interacting factors influence changes in alcohol consumption. Some of these factors act early in the acquisition of ethanol consumption and initial escalation, while others contribute to escalation of ethanol consumption at a later stage and are involved in the development of alcohol dependence. There is considerable need for more studies examining escalation associated with the formation of dependence and other hallmark features of AUD, especially studies examining mechanisms, as it is of considerable relevance to understanding and treating AUD.

Artificial Intelligence Identified Resilient and Vulnerable Female Rats After Traumatic Stress and Ethanol Exposure: Investigation of Neuropeptide Y Pathway Regulation

Post-traumatic stress disorder (PTSD) is initiated by traumatic-stress exposure and manifests into a collection of symptoms including increased anxiety, sleep disturbances, enhanced response to triggers, and increased sympathetic nervous system arousal. PTSD is highly co-occurring with alcohol use disorder. Only some individuals experiencing traumatic stress develop PTSD and a subset of individuals with PTSD develop co-occurring alcohol use disorder. To investigate the basis of these individual responses to traumatic stress, single prolonged stress (SPS) a rodent model of traumatic stress was applied to young adult female rats. Individual responses to SPS were characterized by measuring anxiety-like behaviors with open field and elevated plus maze tests. Rats were then allowed to drink ethanol under an intermittent two bottle choice procedure for 8 weeks, and ethanol consumption was measured. An artificial intelligence algorithm was built to predict resilient and vulnerable individuals based on data from anxiety testing and ethanol consumption. This model was implemented in a second cohort of rats that underwent SPS without ethanol drinking to identify resilient and vulnerable individuals for further study. Analysis of neuropeptide Y (NPY) levels and expression of its receptors Y1R and Y2R mRNA in the central nucleus of the amygdala (CeA), basolateral amygdala (BLA), and bed nucleus stria terminalis (BNST) were performed. Results demonstrate that resilient rats had higher expression of Y2R mRNA in the CeA compared with vulnerable and control rats and had higher levels of NPY protein in the BNST compared to controls. The results of the study show that an artificial intelligence algorithm can identify individual differences in response to traumatic stress which can be used to predict subsequent ethanol drinking, and the NPY pathway is differentially altered following traumatic stress exposure in resilient and vulnerable populations. Understanding neurochemical alterations following traumatic-stress exposure is critical in developing prevention strategies for the vulnerable phenotype and will help further development of novel therapeutic approaches for individuals suffering from PTSD and at risk for alcohol use disorder.

Optogenetic manipulation of the prelimbic cortex during fear memory reconsolidation alters fear extinction in a preclinical model of comorbid PTSD/AUD

RATIONALE AND OBJECTIVE

Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are disorders of learning and memory that often occur comorbidly. Exposure to trauma-related cues can increase alcohol intake in PTSD patients that are using alcohol to self-medicate. The recurrence of anxiety symptoms with subsequent alcohol use may initiate a destructive cycle where stress and alcohol exposure impair the function of the prefrontal cortex (PFC). While the incidence of these disorders has steadily increased, current therapies and treatments often lack efficacy. Thus, investigation into the underlying neurocircuitry responsible for the establishment and maintenance of these disorders is necessary to develop novel treatment targets.

METHODS

The present study examined the effects of ethanol exposure on the ability to create new learned associations around previously conditioned fear cues in a rat model. Animals were exposed to fear conditioning followed by chronic intermittent ethanol to translationally model trauma exposure followed by alcohol abuse. Optogenetics was used to inhibit the prelimbic (PrL) or infralimbic (IfL) cortex during fear memory reconsolidation, and fear behaviors were measured during subsequent extinction and spontaneous recovery tests. Results and conclusion Chronic ethanol exposure led to deficits in fear extinction learning and increased freezing during spontaneous recovery, both of which were prevented following inhibition of the PrL, but not the IfL, during memory reconsolidation. These results support the involvement of the PrL in fear learning and memory, and strongly suggest that the PrL could serve as a potential target for the treatment of the learning and memory deficits that occur following exposure to stress and alcohol.

Hypoactive Thalamic Crh+ Cells in a Female Mouse Model of Alcohol Drinking After Social Trauma

BACKGROUND

Comorbid stress-induced mood and alcohol use disorders are increasingly prevalent among female patients. Stress exposure can disrupt salience processing and goal-directed decision making, contributing to persistent maladaptive behavioral patterns; these and other stress-sensitive cognitive and behavioral processes rely on dynamic and coordinated signaling by midline and intralaminar thalamic nuclei. Considering the role of social trauma in the trajectory of these debilitating psychopathologies, identifying vulnerable thalamic cells may provide guidance for targeting persistent stress-induced symptoms.

METHODS

A novel behavioral protocol traced the progression from social trauma to the development of social defensiveness and chronically escalated alcohol consumption in female mice. Recent cell activation-measured as cFos-was quantified in thalamic cells after safe social interactions, revealing stress-sensitive corticotropin-releasing hormone-expressing (Crh+) anterior central medial thalamic (aCMT) cells. These cells were optogenetically stimulated during stress-induced social defensiveness and abstinence-escalated binge drinking.

RESULTS

Crh+ aCMT neurons exhibited substantial activation after social interactions in stress-naïve but not in stressed female mice. Photoactivating Crh+ aCMT cells dampened stress-induced social deficits, whereas inhibiting these cells increased social defensiveness in stress-naïve mice. Optogenetically activating Crh+ aCMT cells diminished abstinence-escalated binge alcohol drinking in female mice, regardless of stress history.

CONCLUSIONS

This work uncovers a role for Crh+ aCMT neurons in maladaptive stress-induced social interactions and in binge drinking after forced abstinence in female mice. This molecularly defined thalamic cell population may serve as a critical stress-sensitive hub for social deficits caused by exposure to social trauma and for patterns of excessive alcohol drinking in female populations.

Importance of sex and trauma context on circulating cytokines and amygdalar GABAergic signaling in a comorbid model of posttraumatic stress and alcohol use disorders

Alcohol use disorder (AUD) and anxiety disorders are frequently comorbid and share mechanisms that could be therapeutic targets. To facilitate mechanistic studies, we adapted an inhibitory avoidance-based "2-hit" rat model of posttraumatic stress disorder (PTSD) and identified predictors and biomarkers of comorbid alcohol (ethanol)/PTSD-like symptoms in these animals. Stressed Wistar rats received a single footshock on two occasions. The first footshock occurred when rats crossed into the dark chamber of a shuttle box. Forty-eight hours later, rats received the second footshock in a familiar (FAM) or novel (NOV) context. Rats then received 4 weeks of two-bottle choice (2BC) ethanol access. During subsequent abstinence, PTSD-like behavior responses, GABAergic synaptic transmission in the central amygdala (CeA), and circulating cytokine levels were measured. FAM and NOV stress more effectively increased 2BC drinking in males and females, respectively. Stressed male rats, especially drinking-vulnerable individuals (≥0.8 g/kg average 2-h ethanol intake with >50% ethanol preference), showed higher fear overgeneralization in novel contexts, increased GABAergic transmission in the CeA, and a profile of increased G-CSF, GM-CSF, IL-13, IL-6, IL-17a, leptin, and IL-4 that discriminated between stress context (NOV > FAM > Control). However, drinking-resilient males showed the highest G-CSF, IL-13, and leptin levels. Stressed females showed increased acoustic startle and decreased sleep maintenance, indicative of hyperarousal, with increased CeA GABAergic transmission in NOV females. This paradigm promotes key features of PTSD, including hyperarousal, fear generalization, avoidance, and sleep disturbance, with comorbid ethanol intake, in a sex-specific fashion that approximates clinical comorbidities better than existing models, and identifies increased CeA GABAergic signaling and a distinct pro-hematopoietic, proinflammatory, and pro-atopic cytokine profile that may aid in treatment.

ADHD symptoms as risk factor for PTSD in inpatients treated for alcohol use disorder

Attention deficit hyperactivity disorder (ADHD) and post-traumatic stress disorder (PTSD) are more common in alcohol use disorder (AUD) patients than in the general population. Still, there is a lack of knowledge about the relationship between the two conditions in these patients. The main objective of this study was to examine the prevalence of ADHD symptoms, and the relationship between ADHD symptoms and PTSD in AUD inpatients in treatment. Data from 85 AUD patients were collected. The Adult ADHD Self-Report Scale (ASRS) was used to measure ADHD symptoms in all patients. Differences between groups split by PTSD diagnosis and by ASRS clinical cut-off were described, and the relationship between ADHD symptom level and PTSD was tested in a multiple regression model. Almost half the patients scored above ASRS cut-off and 14% had PTSD. Of the patients whose score was above cut-off on the ASRS 23% had PTSD, versus 7% among those below cut-off. Higher ASRS score was associated with PTSD even when age, sex and trauma were adjusted for. This study confirms the high level of ADHD symptoms in AUD patients in treatment. Diagnostic evaluation of PTSD is recommended in patients with ADHD attending inpatient treatment programs for AUD.

A unifying translational framework to advance treatment research for comorbid PTSD and substance use disorders

We provide a unifying translational framework that can be used to synthesize extant lines of human laboratory research in four neurofunctional domains that underlie the co-occurrence of posttraumatic stress and substance use disorders (PTSD+SUD). We draw upon the Alcohol and Addiction Research Domain Criteria (AARDOC) to include executive functioning, negative emotionality, reward, and added social cognition from the National Institute of Mental Health (NIMH) Research Domain Criteria into our framework. We review research findings across each of the four domains, emphasizing human experimental studies in PTSD, SUD, and PTSD+SUD for each domain. We also discuss the implications of research findings for treatment development by considering new ways of conceptualizing risk factors and outcomes at the level of the individual patient, which will enhance treatment matching and advance innovations in intervention.

High ethanol preference and dissociated memory are co-occurring phenotypes associated with hippocampal GABAAR-δ receptor levels

Alcohol use disorder (AUD) frequently co-occurs with dissociative disorders and disorders with dissociative symptoms, suggesting a common neurobiological basis. It has been proposed that facilitated information processing under the influence of alcohol, resulting in the formation of dissociated memories, might be an important factor controlling alcohol use. Access to such memories is facilitated under the effect of alcohol, thus further reinforcing alcohol use. To interrogate possible mechanisms associated with these phenotypes, we used a mouse model of dissociative amnesia, combined with a high-alcohol preferring (HAP) model of AUD. Dissociated memory was induced by activation of hippocampal extrasynaptic GABA type A receptor delta subunits (GABA_AR-δ), which control tonic inhibition and to which ethanol binds with high affinity. Increased ethanol preference was associated with increased propensity to form dissociated memories dependent on GABA_AR-δ in the dorsal hippocampus (DH). Furthermore, the DH level of GABA_AR-δ protein, but not mRNA, was increased in HAP mice, and was inversely correlated to the level of miR-365-3p, suggesting an miRNA-mediated post-transcriptional mechanism contributing to elevated GABA_AR-δ. The observed changes of DH GABA_AR-δ were associated with a severe reduction of excitatory projections stemming from GABA_AR-δ-containing pyramidal neurons in the subiculum and terminating in the mammillary body. These results suggest that both molecular and circuit dysfunction involving hippocampal GABA_AR-δ receptors might contribute to the co-occurrence of ethanol preference and dissociated information processing.