Connecting the pathology of posttraumatic stress and substance use disorders: monoamines and neuropeptides

Coping motives mediate the relationship between PTSD and MDMA use in adolescents with substance use disorders

BACKGROUND

Post-traumatic stress disorder (PTSD) and substance use disorders (SUDs) often co-occur in adolescent patients. Previous research has shown that these patients differ from SUD patients without PTSD in terms of their substance use patterns. In this study, we aimed to test whether substance use in this population is related to an attempt to self-medicate PTSD-related symptoms.

METHODS

German adolescent patients (aged 13-18 years) at an outpatient clinic for SUD treatment, n = 111 (43% female), completed a self-designed questionnaire on use motives, a measure of PTSD-related experiences, and underwent a standardized psychiatric interview including structured substance use questions. Participants were subsequently classified as 'no traumatic experiences ('noTEs' but SUD), 'traumatic experiences but no current PTSD diagnosis' ('TEs' with SUD), and 'PTSD' with SUD. After establishing a self-designed motive measurement through exploratory and confirmatory factor analyses, we calculated non-parametric group differences and a mediation analysis in a linear regression framework.

RESULTS

The past-year frequency of MDMA use was highest in the PTSD group and lowest in the noTE group (H (2) = 7.2, p = .027, η2 = .058), but no differences were found for frequencies of tobacco, alcohol, cannabis, or stimulant use (all H ≤ 4.9, p ≥ .085, η2 ≤ .033). While controlling for sex, the three groups showed a similar pattern (highest in the PTSD group and lowest in the noTE group) for coping scores (F (103) = 5.77, p = .004, η2 = .101). Finally, mediation analyses revealed an indirect effect of coping score (b = 0.61, 95% CI [0.29, 1.58], p = .145) on the association between group membership and MDMA use frequency.

CONCLUSIONS

In adolescent SUD patients, we found an association of current PTSD and lifetime traumatic experiences with higher MDMA use that could be partially explained by substance use being motivated by an attempt to cope with mental health symptoms. This indicates a coping process involved specifically in MDMA use compared to the use of other psychoactive substances, possibly due to unique psychoactive effects of MDMA.

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.

Invisible wounds: Suturing the gap between the neurobiology, conventional and emerging therapies for posttraumatic stress disorder

A sharp increase in the prevalence of neuropsychiatric disorders, including major depression, anxiety, substance use disorders and posttraumatic stress disorder (PTSD) has occurred due to the traumatic nature of the persisting COVID-19 global pandemic. PTSD is estimated to occur in up to 25% of individuals following exposure to acute or chronic trauma, and the pandemic has inflicted both forms of trauma on much of the population through both direct physiological attack as well as an inherent upheaval to our sense of safety. However, despite significant advances in our ability to define and apprehend the effects of traumatic events, the neurobiology and neuroanatomical circuitry of PTSD, one of the most severe consequences of traumatic exposure, remains poorly understood. Furthermore, the current psychotherapies or pharmacological options for treatment have limited efficacy, durability, and low adherence rates. Consequently, there is a great need to better understand the neurobiology and neuroanatomy of PTSD and develop novel therapies that extend beyond the current limited treatments. This review summarizes the neurobiological and neuroanatomical underpinnings of PTSD and discusses the conventional and emerging psychotherapies, pharmacological and combined psychopharmacological therapies, including the use of psychedelic-assisted psychotherapies and neuromodulatory interventions, for the improved treatment of PTSD and the potential for their wider applications in other neuropsychiatric disorders resulting from traumatic exposure.

[Comorbidity of posttraumatic stress disorder and addiction from a biopsychosocial perspective]

Posttraumatic stress disorder and substance use disorder often co-occur within the health care system. Their comorbidity is associated with more serious acute clinical symptomatology, more frequent hospital admissions in state of emergency and significantly lower chances of improvement by psychological and pharmacological treatment. Their comorbidity contributes to dramatically unfavourable courses of illness as regards all biopsychosocial levels. The survey presented will discuss empirical findings from various perspectives: general epidemiology, substance use disorder as risk factor of trauma and PTSD, trauma and PTSD as risk factor of SUD, neurobiological effects of SUD converging towards neurobiology of PTSD, shared common factors of genetics/epigenetics, personality traits, and early developmental stress and trauma. The main focus of analysis will be put on processes that are intrinsically linked to the development and course of both disorders.

Frustrative nonreward and emotional self-medication:Factors modulating alcohol consumption following reward downshift in rats

Life experience involving unexpected incentive loss (e.g., loss of job or a significant other) may result in negative emotional reactions (frustration) and promote alcohol drinking. Similarly, animals exposed to a frustrative 32-to-4% sucrose downshift increase their preference for alcohol (2%) vs. water. This result was interpreted as reflecting emotional self-medication-the consumption of substances that reduce negative emotions. We conducted three experiments examining parametric manipulations of the animal model: (1) effects of a severe reward downshift (32-to-4% sucrose) on consumption of various alcohol concentrations (Experiment 1); (2) effects of different magnitudes of reward downshifts on consumption of 32% alcohol (Experiment 2); and (3) effects of partial reinforcement (an intervention that increases resistance to frustration) on 2% alcohol intake induced by a 32-to-4% sucrose downshift (Experiment 3). The results show that (1) a 32-to-4% sucrose downshift leads to an increase in alcohol intake over a wide range of alcohol concentrations; (2) the greater the reward downshift, the higher the relative increase in alcohol consumption; and (3) a treatment that increases resistance to frustration (partial reinforcement) also attenuates alcohol consumption after a sucrose downshift. These data are discussed in relation to the role of frustrative nonreward in alcohol consumption.

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.

Effectiveness of drugs acting on adrenergic receptors in the treatment for tobacco or alcohol use disorders: systematic review and meta-analysis

AIM

To assess the efficacy of drugs directly acting on alpha- and beta-adrenergic receptors in the treatment of patients suffering from tobacco or alcohol use disorder.

METHODS

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, studies were identified through PUBMED, EMBASE, the Cochrane Central Register of Controlled Trials and clinicaltrial.gov. We selected only randomized controlled trials with adult patients with tobacco or alcohol use disorders according to DSM-5 criteria. Interventions included any molecule having a direct pharmacological action on alpha- or beta-adrenergic receptors (agonist or antagonist). Comparators were placebo or other validated pharmacotherapies. The duration of the intervention was a minimum of 1 month, with 3 months of follow-up. Measurements included smoking cessation for tobacco; for alcohol, we selected abstinence, alcohol consumption (drinks per day or week) and heavy drinking days (HDD). Ten studies with tobacco and six with alcohol use disorder were included in the qualitative synthesis and fifteen studies in the quantitative analysis.

RESULTS

We found that clonidine, an alpha-2 agonist, significantly increased smoking abstinence [relative risk = 1.39 with a 95% confidence interval (CI) = 1.04, 1.84]. Beta-blockers had no significant effect on smoking abstinence. The alpha-1 antagonists prazosin and doxazosin decreased alcohol consumption [SMD = -0.32 (-0.56, -0.07)] but had no effect on abstinence or HDD.

CONCLUSIONS

The noradrenaline system may represent a promising mechanism to target in tobacco and alcohol use disorders.

An Integrated Model of Nature and Nurture Factors that Contribute to Addiction and Recovery

BACKGROUND

In the context of the opioid epidemic and growing awareness of addiction as a public health concern, there are efforts to inform the public, patients, families, and policy makers about the factors that contribute to addiction and facilitate recovery. Several theoretical models provide useful frameworks for this discussion, but each of them has limitations.

OBJECTIVES

This paper presents an accessible yet comprehensive theoretical model that integrates empirical evidence about addiction etiology and recovery using the nature-nurture paradigm.

RESULTS

The model presents substance use along a continuum, and identifies risk and protective factors in multiple domains that have been identified by research. The domains on the nature side of the model include genetic and biological factors, comorbid psychiatric and medical disorders, physiological reinforcement of substance use, and changes to neural mechanisms. The domains on the nurture side of the model include sociocultural factors, environmental factors, personality, emotions, cognitions, psychological reinforcement of substance use, and cognitive and behavioral changes. The progression from increased or decreased substance use to addiction or recovery is mediated by changes in neural mechanisms and cognitive and behavioral changes, which have feedback loops with the physiological and psychological reinforcement.Conclusions/Importance: This model is a useful heuristic, consistent with a public health framework, for discussing addiction and recovery with patients, their families, and the public. This integrated model of nature and nurture factors has the potential to inform clinical practice, consultation, research, prevention programs, educational programs, and public policy.

Additive influences of acute early life stress and sex on vulnerability for aversion-resistant alcohol drinking

Acute early life stress (ELS) alters stress system functioning in adulthood and increases susceptibility to posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD). The current study assessed the effects of acute, infant ELS on alcohol drinking, including aversion-resistant drinking, in male and female Long Evans rats. Acute ELS was induced using a stress-enhanced fear learning (SEFL) protocol that consisted of 15 footshocks delivered on postnatal day (PND) 17. Alcohol drinking during adolescence and adulthood was measured with a two-bottle choice intermittent alcohol access paradigm. Aversion-resistant drinking was assessed in adulthood by adding quinine (0.01, 0.1, and 1.0 g/L) to the alcohol bottle after 5 to 6 weeks and 11 to 12 weeks of drinking. ELS had minimal influences on adolescent and adult alcohol consumption and preference. However, ELS, sex, and alcohol exposure history all influenced aversion-resistant alcohol drinking in an additive fashion. Higher concentrations of quinine were tolerated in females, ELS-exposed rats, and after 11 to 12 weeks of drinking. Tests of quinine sensitivity in a separate cohort of animals found that rats can detect concentrations of quinine as low as 0.001 g/L in water and that quinine sensitivity is not influenced by sex or ELS exposure. These results agree with reports of sex differences in aversion-resistant drinking and are the first to demonstrate an influence of ELS on this behavior. Our results also suggest that a single traumatic stress exposure in infancy may be a promising model of comorbid PTSD and AUD and useful in studying the interactions between ELS, sex, and alcohol dependence.

Cross-lagged effects of posttraumatic stress disorder symptom severity and cigarette smoking among OEF/OIF/OND veterans

OBJECTIVES

Veterans with posttraumatic stress disorder (PTSD) are known to smoke cigarettes at elevated levels in comparison to both veterans without PTSD and civilians. This study aims to elucidate how cigarette smoking and PTSD symptoms interact over time.

MATERIALS AND METHODS

This study examined the directionality and strength of the relationship between average daily cigarette smoking and PTSD symptom severity across three (T1-T3) time points in a large cohort (N = 851) of male and female Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn returning veterans who were either current or former smokers at T1 (mean age = 37.56; standard deviation = 10.10). We used cross-lagged panel analyses to evaluate their temporal relations.

RESULTS

The analyses indicated that PTSD symptom severity at T1 significantly predicted cigarette smoking at T2, and this predictive association was maintained from T2 to T3. Conversely, smoking at T1 and T2 did not predict PTSD symptom severity at T2 and T3, respectively. Although effect sizes were small, PTSD symptom severity was cross-sectionally related to smoking at T1 and T2, but not T3. In addition, when analyses were examined by gender, the same results were found except these associations were stronger for women than for men cross-sectionally.

CONCLUSION

Our findings provide some evidence of a longitudinal association between PTSD symptom severity and tobacco use and highlight potential targets of intervention.

Childhood Trauma, Cognitive Emotion Regulation and Motivation for Behavior Change Among Clients of Opioid Substitution Treatment With and Without Past Year Synthetic Cathinone Use During Therapy

Background

With a decrease in heroin's purity and availability in the European drug market, Hungarian opioid dependent patients started to substitute heroin with novel psychoactive substances (NPS) and especially with synthetic cathinones.

Goal

This study aims to assess whether clients of opioid substitution treatment (OST) with and without a history of synthetic cathinone use during therapy differ in (1) the rate and type of experienced childhood trauma, (2) the way they cope with negative life events, (3) their motivation to change substance use behavior, (4) the rate of treatment retention.

Methods

A total of 198 clients of an outpatient centers (Nyírõ Gyula National Institute of Psychiatry and Addictions, Budapest) OST were asked to provide information about their general substance use experiences, including the consumption of NPS during treatment, their childhood traumatic experiences (Childhood Trauma Questionnaire), cognitive emotion regulation strategies (Cognitive Emotion Regulation Questionnaire), their motivation to change substance use behavior (University of Rhode Island Change Assessment Scale) and current psychiatric symptoms (Brief Symptom Inventory). Baseline data was collected in the summer of 2015, while 4 years follow-up data on treatment retention was obtained in the summer of 2019.

Results

The majority of the clients were male (N = 141, 71.2%), receiving methadone as a substitute for opioids (N = 178, 89.9%), while mean age of the full sample was 39.7 (SD = 6.8). Based on a logistic regression model, the odds for past year synthetic cathinone use was higher among clients with more severe psychiatric symptoms (B = 0.8, OR = 2.2, p < 0.01) and among clients who were in treatment for a shorter period of time (B = 0.1, OR = 0.9, p < 0.05). Synthetic cathinone use during treatment was further associated with less adaptive strategies to cope with negative life events. Synthetic cathinone use was also a risk factor for reduced treatment retention (B = -0.8, OR = 0.4, p < 0.05) and was associated with lower odds of being member of a latent class with less severe psychopathological profile (B = -0.9, OR = 0.4, p < 0.05).

Conclusion

Synthetic cathinone use during treatment is associated with poorer treatment outcomes and might be characterized by more severe psychiatric symptoms and amotivation to change substance use among opioid dependent clients.

Animal models of liability to post-traumatic stress disorder: going beyond fear memory

In this review, we advocate a dimensional approach on the basis of candidate endophenotypes to the development of animal models of post-traumatic stress disorder (PTSD) capable of including genetic liability factors, variations in symptoms profile and underlying neurobiological mechanisms, and specific comorbidities. Results from the clinical literature pointed to two candidate endophenotypes of PTSD: low sensory gating and high waiting impulsivity. Findings of comparative studies in mice of two inbred strains characterized by different expressions of the two candidate endophenotypes showed different strain-specific neural and behavioral effects of stress experiences. Thus, mice of the standard C57BL/6J strain show stress-induced helplessness, stress-learned helplessness, and stress-extinction-resistant conditioned freezing. Instead, mice of the genetically unrelated DBA/2J strain, expressing both candidate endophenotypes, show stress-induced extinction-resistant avoidance and neural and behavioral phenotypes promoted by prolonged exposure to addictive drugs. These strain differences are in line with evidence of associations between genetic variants and specific stress-promoted pathological profiles in PTSD, support a role of genotype in determining different PTSD comorbidities, and offer the means to investigate specific pathogenic processes.

Dopamine D2/D3 receptor agonists attenuate PTSD-like symptoms in mice exposed to single prolonged stress

Medications that enhance dopaminergic neurotransmission can be useful in the pharmacotherapy of posttraumatic stress disorder (PTSD), which manifests as fearful memory retrieval, anxiety and depression. We examined the effects of subchronic (15 days) treatment with select dopaminergic medications, including bromocriptine, modafinil, dihydrexidine, rotigotine and pramipexole, in a mouse model of PTSD induced by single prolonged stress (mSPS). The potential antidepressant-like and anxiolytic effects of the medications were measured by the forced swim test (FST) and the elevated plus maze (EPM) test, respectively. In addition, we studied the effects of these medications on memory retrieval in an auditory fear conditioning (FC) test, on ultrasonic vocalizations (USVs) induced by restraint stress, and on spontaneous locomotor activity (SLA). We report that a single exposure to a severe and complex set of stressors several days before testing increased immobility time in the FST and freezing in the FC paradigm and reduced the time spent in the open arms of the EPM. The stressed mice also displayed increased USVs, especially the short type. While none of the tested dopamine-mimetics exhibited anxiolytic-like effects, rotigotine produced antidepressant-like activity specifically in the mSPS-exposed animals. Moreover, both rotigotine and pramipexole shortened the duration of freezing in the fear conditioning test, but only in the mSPS-exposed mice. This study supports the hypothesis that the activation of dopaminergic D2/D3 receptors may be a promising pharmacotherapy for PTSD.

Recent advances in the neurobiology of posttraumatic stress disorder: A review of possible mechanisms underlying an effective pharmacotherapy

Recent progress in the field of neurobiology supported by clinical evidence gradually reveals the mystery of human brain functioning. So far, many psychiatric disorders have been described in great detail, although there are still plenty of cases that are misunderstood. These include posttraumatic stress disorder (PTSD), which is a unique disease that combines a wide range of neurobiological changes, which involve disturbances of the hypothalamic-pituitary-adrenal gland axis, hyperactivation of the amygdala complex, and attenuation of some hippocampal and cortical functions. Such multiplicity results in differential symptomatology, including elevated anxiety, nightmares, fear retrieval episodes that may trigger delusions and hallucinations, sleep disturbances, and many others that strongly interfere with the quality of the patient's life. Because of widespread neurological changes and the disease manifestation, the pharmacotherapy of PTSD remains unclear and requires a multidimensional approach and involvement of polypharmacotherapy. Hopefully, more and more neuroscientists and clinicians will study PTSD, which will provide us with new information that would possibly accelerate establishment of well-tolerated and effective pharmacotherapy. In this review, we have focused on neurobiological changes regarding PTSD, addressing the most disturbed brain structures and neurotransmissions, as well as discussing in detail the recently taken and novel therapeutic paths.

Posttraumatic stress disorder and tobacco use: A systematic review and meta-analysis

Posttraumatic stress disorder (PTSD) and tobacco use are prevalent conditions that co-occur at striking rates in the US. Previous reviews examined prevalence and factors associated with cigarette smoking among individuals with PTSD but have not been summarized since 2007. Moreover, none explored rates and factors associated with the use of other tobacco products. This study aimed to systematically review the most recent literature examining the comorbidity of PTSD and tobacco use to provide prevalence rates, as well as summarize the literature exploring other factors associated with tobacco use among individuals with PTSD. Studies were identified using a systematic search of keywords related to tobacco use and PTSD within the following databases: PubMed, PsycINFO, Web of Knowledge, CINAHL, PsycARTICLES, and Cochrane Clinical Trials Library. The studies included in this review (N = 66) showed that the prevalence of current use of tobacco products in individuals with PTSD was 24.0% and the rate of PTSD among users of tobacco products was 20.2%. Additionally, results demonstrated that individuals with PTSD present with high levels of nicotine dependence and heavy use of tobacco products, as well as underscore the importance of negative emotional states as a contributing factor to tobacco use among individuals with PTSD. It is imperative that future studies continue monitoring tobacco use among individuals with PTSD while also assessing factors identified as having a prominent role in tobacco use among individuals with PTSD. These findings also demonstrate the need for more innovative approaches to reduce the pervasive tobacco use among individuals with PTSD.

Pathways to Retention in HIV Care Among U.S. Veterans

Retaining HIV patients in clinical care is a critical component of the HIV care continuum, impacting not only patients' virologic suppression, but their overall health and wellbeing. Understanding reasons for patient drop-out is therefore important to improve HIV outcomes and reduce transmission. This study used qualitative in-depth interviews with patients who dropped out of HIV care (n = 16) from the Atlanta Veterans Affairs Medical Center, to explore their reasons for drop-out and how they negotiate barriers to return to care. Results show three interlinked "pathways" leading to patient drop-out -wellness, illness, and medication pathways. These pathways encompass both barriers to retention and triggers to resume clinic visits, with patients following different pathways at different times in their lives. Perhaps the strongest deterrent to continuing clinic visits was participants' self-perception of wellness, which often outweighed clinical indicators of wellness. These pathways suggest that multiple approaches are needed to improve treatment retention, including reducing clinic-based barriers, addressing basic needs that are barriers to clinic visits, and empowering patients to view clinic visits as a facilitator to maintaining their overall health rather than only a reaction to illness.

Imaging corticotropin-releasing-factor and nociceptin in addiction and PTSD models

Addiction is composed of three phases: intoxication, withdrawal, and craving. Negative reinforcement, strengthening a behaviour by removing an aversive stimulus, has been associated with the withdrawal phase. An imbalance of neurotransmitters within the brain's stress (nociceptin, neuropeptide Y) and anti-stress (CRF, norepinephrine, etc.) system is attributed to negatively reinforced compulsive behaviours associated with relapse. Similarly, post-traumatic stress disorder is characterized by an overactive stress system. In a PTSD mouse model, rodents exhibited impaired cued-fear memory consolidation when nociceptin transmission was blocked. Furthermore, a single-nucleotide polymorphism has been identified between women diagnosed with PTSD and the severity of PTSD symptoms, suggesting a genetic basis. Therefore, it is critical to understand the functions and interactions between the brain's stress and anti-stress neurotransmitters, specifically nociceptin. This paper will examine the hypothalamic-pituitary-adrenocortical axis, evaluate the functions of corticotropin-releasing-factor and nociceptin, discuss nociceptin's role as an anxiolytic or anxiogenic, and discuss PET-imaging studies-all of which targeted nociceptin receptors (NOP-R). Finally, the discussion of pharmacological interventions will be proposed as preventative or therapeutic treatments for those suffering from PTSD and substance-use disorders.

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

Post-traumatic stress disorder (PTSD) and alcohol-use disorder (AUD) are highly comorbid in humans. Although we have some understanding of the structural and functional brain changes that define each of these disorders, and how those changes contribute to the behavioral symptoms that define them, little is known about the neurobiology of comorbid PTSD and AUD, which may be due in part to a scarcity of adequate animal models for examining this research question. The goal of this review is to summarize the current state-of-the-science on comorbid PTSD and AUD. We summarize epidemiological data documenting the prevalence of this comorbidity, review what is known about the potential neurobiological basis for the frequent co-occurrence of PTSD and AUD and discuss successes and failures of past and current treatment strategies. We also review animal models that aim to examine comorbid PTSD and AUD, highlighting where the models parallel the human condition, and we discuss the strengths and weaknesses of each model. We conclude by discussing key gaps in our knowledge and strategies for addressing them: in particular, we (1) highlight the need for better animal models of the comorbid condition and better clinical trial design, (2) emphasize the need for examination of subpopulation effects and individual differences and (3) urge cross-talk between basic and clinical researchers that is reflected in collaborative work with forward and reverse translational impact.