The physiological responses to acute stress in alcohol-dependent patients: A systematic review

Impact of provoked stress on model-free and model-based reinforcement learning in individuals with alcohol use disorder

Background

From both clinical and theoretical perspectives, understanding the functionality of evaluative reinforcement learning mechanisms (Model-Free, MF, and Model-Based, MB) under provoked stress, particularly in Alcohol Use Disorder (AUD), is crucial yet underexplored. This study aims to evaluate whether individuals with AUD who do not seek treatment show a greater tendency towards retrospective behaviors (MF) rather than prospective and deliberative simulations (MB) compared to controls. Additionally, it examines the impact of induced social stress on these decision-making processes.

Methods

A cohort comprising 117 participants, including 55 individuals with AUD and 62 controls, was examined. Acute social stress was induced through the socially evaluated cold pressor task (SECPT), followed by engagement in a Two-Step Markov task to assess MB and MF learning tendencies. We measured hypothalamic-pituitary-adrenal axis stress response using salivary cortisol levels.

Results

Both groups showed similar baseline cortisol levels and responses to the SECPT. Our findings indicate that participants with AUD exhibit a reduced reliance on MB strategies compared to those without AUD. Furthermore, stress decreases reliance on MB strategies in healthy participants, but this effect is not observed in those with AUD.

Conclusion

An atypical pattern of stress modulation impacting the balance between MB and MF reinforcement learning was identified in individuals with AUD who are not seeking treatment. Potential explanations for these findings and their clinical implications are explored.

Reciprocal relations between acute interpersonal negative life events and acute alcohol use: An examination of the 24 h preceding suicide attempts among hospitalized patients

OBJECTIVE

To examine the within-person relations between acute alcohol use and interpersonal negative life events (INLEs) in the 24 h preceding suicide attempts.

METHOD

Participants were 151 adult patients (67.55 % female; M age = 36.00) who were hospitalized within 24 h of a suicide attempt. Participants completed the Timeline Follow-back for Suicide Attempts interview to gather information about hourly events for the 24 h preceding their suicide attempt. Hierarchical logistic models were estimated to examine the influence of acute INLEs on next-hour alcohol use and acute alcohol use on next-hour INLEs. Biological sex and chronic alcohol use (past year) were evaluated as potential moderators.

RESULTS

Overall, acute alcohol use was associated with increased odds of next-hour INLEs and acute INLEs were associated with increased odds of next-hour alcohol use. Moderator analyses indicated that the influence of alcohol use on INLEs increased as participants' level of chronic alcohol use decreased, and relations did not vary by biological sex.

CONCLUSIONS

There is a bidirectional relation between INLEs and alcohol use in the hours preceding suicide attempts. Understanding that these within-person interrelations may differ in strength depending on one's level of chronic alcohol use has practical utility for providers tasked with clinical decision making.

Altered Physiological, Affective, and Functional Connectivity Responses to Acute Stress in Patients With Alcohol Use Disorder

Background

There is evidence that the processing of acute stress is altered in alcohol use disorder (AUD), but little is known about how this is manifested simultaneously across different stress parameters and which neural processes are involved. The current study examined physiological and affective responses to stress and functional connectivity in AUD.

Methods

Salivary cortisol samples, pulse rate, and affect ratings were collected on 2 days from 34 individuals with moderate or severe AUD during early abstinence and 34 control participants. On one of the days, stress was induced, and on the other day, a nonstressful control task was performed. Following the intervention, participants underwent functional magnetic resonance imaging to assess functional connectivity, with a focus on cortical and subcortical seed regions previously reported to be involved in AUD and/or stress.

Results

For pulse rate and cortisol, stress responses were blunted in AUD, whereas the affective response was stronger. Neuroimaging analyses revealed stress-related group differences in functional connectivity, involving the connectivity of striatal seeds with the posterior default mode network, cerebellum, and midcingulate cortex and of the posterior default mode network seed with the striatum and thalamus.

Conclusions

The results suggest a dissociation between subjectively experienced distress and the physiological stress response in AUD as well as stress-related alterations in functional connectivity. These findings highlight the complex interplay between chronic alcohol use and acute stress regulation, offering valuable considerations for the development of therapeutic strategies.

Associations of hair cortisol levels with violence, poor mental health, and harmful alcohol and other substance use among female sex workers in Nairobi, Kenya

Violence, poor mental health, and harmful substance use are commonly experienced by female sex workers (FSWs) in sub-Saharan Africa, all of which are associated with increased HIV susceptibility. We aimed to investigate the associations between violence, poor mental health and harmful alcohol/substance use with hair cortisol concentration (HCC) levels as a potential biological pathway linking the experiences of these stressors and HIV vulnerability. We used the baseline data of the Maisha Fiti study of FSWs in Nairobi, Kenya. Participants reported recent violence, poor mental health, and harmful alcohol/substance use. Hair samples proximal to the scalp were collected to measure cortisol levels determined by ELISA. We analysed the data of 425 HIV-negative respondents who provided at least 2 cm of hair sample. The prevalence of recent violence was 89.3% (physical 54.6%; sexual 49.4%; emotional 77.0% and financial 66.5%), and 29.1% had been arrested due to sex work. 23.7% of participants reported moderate/severe depression, 11.6% moderate/severe anxiety, 13.5% PTSD and 10.8% recent suicidal thoughts and/or attempts. About half of the participants (48.8%) reported recent harmful alcohol and/or other substance use. In multivariable linear regression analyses, both physical and/or sexual violence (adjusted geometric mean ratio (aGMR) = 1.28; 95% CI 1.01-1.62) and harmful alcohol and/or other substance use (aGMR = 1.31; 95% CI 1.03-1.65) were positively and independently associated with increased HCC levels. Findings suggest a role of violence and substance use in elevated HCC levels, which could increase HIV risk due to cortisol-related T cell activation. However, longitudinal and mechanistic studies are needed to confirm this hypothesis.

The importance of community engagement in experimental stress and substance use research with marginalized groups: Lessons from research with sexual and gender minority populations

There is a growing need for experimental stress paradigms tailored for use with marginalized groups to better understand the impact of experiencing minoritized stress on substance use outcome. Experimental stress research that examines the role of minority stress in substance use is not only innovative, but also has the potential to improve health equity. However, this research also has anticipated risks. As a result, community-engaged research (CEnR) is critical. CEnR can improve experimental stress and substance use research by engaging applicable communities in research design, recruitment, data interpretation, and dissemination. When conducting CEnR, there are also unique challenges and considerations that need to be taken into account. Recommendations are provided based on prior experiences in experimental stress induction and alcohol research with SGM (sexual and gender minority) groups.

Blunted cortisol and normal sympathetic nervous system responses to an acute psychosocial stressor in internet addiction

Studies have demonstrated that addiction leads to blunted responses of cortisol and sympathetic nervous system (SNS) to acute stressors; however, limited studies have examined the neuroendocrine and SNS stress responses in Internet addiction (IA). To examine acute stress responses in IA, the current study recruited a total of 76 Japanese university students and staff members (51 females and 25 males, mean age = 22.4 years, SD = 4.7), and measured the salivary cortisol, salivary alpha-amylase (sAA), and blood pressure (BP) responses to an acute stressor under stress or a nonstress placebo conditions in IA and non-IA groups. The results revealed that patients with IA showed a blunted cortisol response to a stressor. In contrast, no differences were found in the sAA and BP responses between the IA and non-IA groups. These results suggest that IA may be characterized by blunted cortisol responses in acute stress settings.

The effects of social isolation stress and discrimination on mental health

Social isolation and discrimination are growing public health concerns associated with poor physical and mental health. They are risk factors for increased morbidity and mortality and reduced quality of life. Despite their detrimental effects on health, there is a lack of knowledge regarding translation across the domains of experimental research, clinical studies, and real-life applications. Here, we review and synthesize evidence from basic research in animals and humans to clinical translation and interventions. Animal models indicate that social separation stress, particularly in early life, activates the hypothalamic-pituitary-adrenal axis and interacts with monoaminergic, glutamatergic, and GABAergic neurotransmitter systems, inducing long-lasting reductions in serotonin turnover and alterations in dopamine receptor sensitivity. These findings are of particular importance for human social isolation stress, as effects of social isolation stress on the same neurotransmitter systems have been implicated in addictive, psychotic, and affective disorders. Children may be particularly vulnerable due to lasting effects of social isolation and discrimination stress on the developing brain. The effects of social isolation and loneliness are pronounced in the context of social exclusion due to discrimination and racism, during widespread infectious disease related containment strategies such as quarantine, and in older persons due to sociodemographic changes. This highlights the importance of new strategies for social inclusion and outreach, including gender, culture, and socially sensitive telemedicine and digital interventions for mental health care.

Subjective stress and alcohol use among young adult and adult drinkers: Systematic review of studies using Intensive Longitudinal Designs

Background: Understanding how stress dynamically associates with alcohol use could provide a finer-grain resolution of drinking behavior, facilitating development of more effective and personalized interventions. The primary aim of this systematic review was to examine research using Intensive Longitudinal Designs (ILDs) to determine if greater naturalistic reports of subjective stress (e.g., those assessed moment-to-moment, day-to-day) in alcohol-drinkers associated with a) greater frequency of subsequent drinking, b) greater quantity of subsequent drinking, and c) whether between-/within-person variables moderate or mediate any relationships between stress and alcohol use. Methods: Using PRISMA guidelines, we searched EMBASE, PubMed, PsycINFO, and Web of Science databases in December 2020, ultimately identifying 18 eligible articles, representing 14 distinct studies, from a potential pool of 2,065 studies. Results: Results suggested subjective stress equivocally predicted subsequent alcohol use; in contrast, alcohol use consistently demonstrated an inverse relationship with subsequent subjective stress. These findings remained across ILD sampling strategy and most study characteristics, except for sample type (treatment-seeking vs. community/collegiate). Conclusions: Results appear to emphasize the stress-dampening effects of alcohol on subsequent stress levels and reactivity. Classic tension-reduction models may instead be most applicable to heavier-drinking samples and appear nuanced in lighter-drinking populations, and may depend on specific moderators/mediators (e.g., race/ethnicity, sex, relative coping-strategy use). Notably, a preponderance of studies utilized once-daily, concurrent assessments of subjective stress and alcohol use. Future studies may find greater consistency by implementing ILDs that integrate multiple within-day signal-based assessments, theoretically-relevant event-contingent prompts (e.g., stressor-occurrence, consumption initiation/cessation), and ecological context (e.g., weekday, alcohol availability).

α6-Containing GABAA Receptors: Functional Roles and Therapeutic Potentials

GABAA receptors containing the α6 subunit are highly expressed in cerebellar granule cells and less abundantly in many other neuronal and peripheral tissues. Here, we for the first time summarize their importance for the functions of the cerebellum and the nervous system. The cerebellum is not only involved in motor control but also in cognitive, emotional, and social behaviors. α6βγ2 GABAA receptors located at cerebellar Golgi cell/granule cell synapses enhance the precision of inputs required for cerebellar timing of motor activity and are thus involved in cognitive processing and adequate responses to our environment. Extrasynaptic α6βδ GABAA receptors regulate the amount of information entering the cerebellum by their tonic inhibition of granule cells, and their optimal functioning enhances input filtering or contrast. The complex roles of the cerebellum in multiple brain functions can be compromised by genetic or neurodevelopmental causes that lead to a hypofunction of cerebellar α6-containing GABAA receptors. Animal models mimicking neuropsychiatric phenotypes suggest that compounds selectively activating or positively modulating cerebellar α6-containing GABAA receptors can alleviate essential tremor and motor disturbances in Angelman and Down syndrome as well as impaired prepulse inhibition in neuropsychiatric disorders and reduce migraine and trigeminal-related pain via α6-containing GABAA receptors in trigeminal ganglia. Genetic studies in humans suggest an association of the human GABAA receptor α6 subunit gene with stress-associated disorders. Animal studies support this conclusion. Neuroimaging and post-mortem studies in humans further support an involvement of α6-containing GABAA receptors in various neuropsychiatric disorders, pointing to a broad therapeutic potential of drugs modulating α6-containing GABAA receptors. SIGNIFICANCE STATEMENT: α6-Containing GABAA receptors are abundantly expressed in cerebellar granule cells, but their pathophysiological roles are widely unknown, and they are thus out of the mainstream of GABAA receptor research. Anatomical and electrophysiological evidence indicates that these receptors have a crucial function in neuronal circuits of the cerebellum and the nervous system, and experimental, genetic, post-mortem, and pharmacological studies indicate that selective modulation of these receptors offers therapeutic prospects for a variety of neuropsychiatric disorders and for stress and its consequences.