Age at First Intoxication and Alcohol Use Disorders in Southwest California Indians

Adolescent alcohol drinking interaction with the gut microbiome: implications for adult alcohol use disorder

Reciprocal communication between the gut microbiota and the brain, commonly referred to as the "gut-brain-axis" is crucial in maintaining overall physiological homeostasis. Gut microbiota development and brain maturation (neuronal connectivity and plasticity) appear to be synchronized and to follow the same timeline during childhood (immature), adolescence (expansion) and adulthood (completion). It is important to note that the mesolimbic reward circuitry develops early on, whereas the maturation of the inhibitory frontal cortical neurons is delayed. This imbalance can lead to increased acquirement of reward-seeking and risk-taking behaviors during adolescence, and consequently eventuate in heightened risk for substance abuse. Thus, there is high initiation of alcohol drinking in early adolescence that significantly increases the risk of alcohol use disorder (AUD) in adulthood. The underlying causes for heightened AUD risk are not well understood. It is suggested that alcohol-associated gut microbiota impairment during adolescence plays a key role in AUD neurodevelopment in adulthood. Furthermore, alcohol-induced dysregulation of microglia, either directly or indirectly through interaction with gut microbiota, may be a critical neuroinflammatory pathway leading to neurodevelopmental impairments and AUD. In this review article, we highlight the influence of adolescent alcohol drinking on gut microbiota, gut-brain axis and microglia, and eventual manifestation of AUD. Furthermore, novel therapeutic interventions via gut microbiota manipulations are discussed briefly.

A multicomponent ethanol response battery across a cumulative dose ethanol challenge reveals diminished adolescent rat ethanol responsivity relative to adults

Adolescence is a conserved developmental period associated with low alcohol responsivity, which can contribute to heavy drinking and development of an alcohol use disorder (AUD) later in life. To investigate ethanol responsivity between adolescent and adult rats, we developed an ethanol response battery (ERB) to assess acute ethanol responses across cumulative doses of ethanol during the rising phase of the blood ethanol curve. We tested the hypothesis that adolescent male and female rats would exhibit lower ethanol responsivity to a cumulative ethanol challenge relative to adults. Male and female adolescent (postnatal day [P]40) and adult (P85) Wistar rats underwent ERB assessment following consecutive doses of ethanol (i.e., 1.0, 1.0, and 1.0 g/kg) to produce cumulative ethanol doses of 0.0, 1.0, 2.0, and 3.0 g/kg. The ERB consisted of (1) the 6-point behavioral intoxication rating scale, (2) body temperature assessment, (3) tail blood collection, (4) accelerating rotarod assessment, (5) tilting plane assessment, and (6) loss of righting reflex (LORR) assessment. Across cumulative ethanol doses, adolescent and adult rats evidenced progressive changes in ERB measures. On the ERB, adolescent rats of both sexes evidenced (1) lower intoxication rating, (2) blunted hypothermic responses, particularly in females, (3) longer latencies to fall from the accelerating rotarod, and (4) less tilting plane impairment relative to adults despite comparable BECs. All adult rats, regardless of sex, displayed a LORR at the 3.0 g/kg cumulative ethanol dose while among the adolescent rats, only one male rat and no females showed the LORR. These data reveal decreased adolescent ethanol responsivity across body temperature, intoxication, balance, and coordination responses to a cumulative ethanol challenge as assessed using the novel ERB relative to adults. The results of this study suggest that adolescent-specific low ethanol responsivity may contribute to adolescent binge drinking and increased risk for development of an AUD.

Event-related Oscillations to Emotional Faces are Related to a History of Internalizing Disorders

Event-related oscillations (EROs) may represent sensitive biomarkers or endophenotypes for disorders that underlie risk behaviors such as suicidal thoughts and actions. In this study, young adults of American Indian (AI) (n = 821) and Mexican American (MA) (n = 721) ancestry (age 18-30 yrs) were clinically assessed for internalizing and externalizing disorders, and an internalizing scale was generated by extracting core diagnostic items from 6 lifetime DSM5-compatible diagnoses (social phobia, panic disorder, agoraphobia, obsessive compulsive disorder, post-traumatic stress disorder, major depressive episode) and symptoms of suicidality. EROs were generated to sad, happy and neutral faces, and energy and phase locking of delta ERO oscillations were assessed in frontal areas. An increase in delta ERO energy was found in the frontal lead (FZ) following presentation of the sad facial expressions in those with a history of 10 or more internalizing symptoms compared to those with no symptoms. Increases in delta ERO energy in FZ were also associated with a diagnosis of major depressive disorder (MDD), but not with anxiety disorders or antisocial personality disorder/conduct disorders (ASP). Major depression was also associated with increases in cross-cortical phase-locking (FZ-PZ). A decrease in the percentage of correctly identified neutral faces also was seen among those with 10 or more internalizing symptoms compared to those without internalizing symptoms, and in those with anxiety disorders, but not in those with ASP or MDD as compared to their controls. These findings suggest ERO measures may represent important potential biomarkers of depressive disorders as well as risk indicators for suicidal behaviors.

Use of a Fitbit-like device in rats: Sex differences, relation to EEG sleep, and use to measure the long-term effects of adolescent ethanol exposure

BACKGROUND

Sleep difficulties and rhythm disturbances are some of the problems associated with adolescent binge drinking. Recently, animal models of alcohol-induced insomnia have been developed. However, studies in human subjects have recently focused not only on nighttime EEG findings but also on daytime sleepiness and disrupted activity levels as typically measured by activity tracking devices such as the "Fitbit." We sought to develop and test a Fitbit-like device (the "FitBite") in rats and use it to track rest-activity cycles following adolescent alcohol exposure.

METHODS

The effects of 5 weeks of adolescent ethanol vapor or control conditions were evaluated in 48 male and female Wistar rats using FitBite activity while intoxicated, and during acute (24 h post-vapor exposure) and chronic withdrawal (4 weeks post-vapor exposure). Data were analyzed using activity count and cosinor analyses. Fourteen rats were subsequently implanted with cortical electrodes, and data from the FitBite were compared with EEG data to determine how well the FitBite could identify sleep and activity cycles.

RESULTS

Female rats were generally more active than males, with higher circadian rhythm amplitudes and mesors (rhythm-adjusted means) across a 24-h period. There were significant correlations between EEG-estimated sleep and activity counts using the FitBite. When the rats were tested during intoxication after 4 weeks of ethanol vapor exposure, they had significantly less overall activity. Disruptions in circadian rhythm were also found with significant decreases in the circadian amplitude, mesor, and a later shift in the acrophase. At 24 h of ethanol withdrawal, rats had more episodes of activity with shorter durations during the daytime, when rats are expected to spend more of their time sleeping. This effect remained at 4 weeks following withdrawal, but circadian rhythm disruptions were no longer present.

CONCLUSIONS

A Fitbit-like device can be successfully used in rats to assess rest-activity cycles. Adolescent alcohol exposure produced circadian rhythm disturbances that were not observed after withdrawal. Fragmentation of ultradian rest-activity cycles during the light period was found at 24 h and 4 weeks after withdrawal and support data demonstrating the presence of sleep disturbance long after alcohol withdrawal.

Extreme Binge Drinking During Adolescence: Associations With Subsequent Substance Use Disorders in American Indian and Mexican American Young Adults

OBJECTIVE

This study collected retrospective data on adolescent binge drinking (ABD) (5 drinks for boys, 4 for girls per occasion at least once per month) and/or extreme adolescent binge drinking (EABD) (10 or more drinks per occasion at least once per month) and tested for associations with demographic and diagnostics variables including alcohol and other substance use disorders (AUD/SUD).

METHODS

Cross-sectional data were collected from young adult (age 18-30 yrs) American Indians (AI) (n = 534) and Mexican Americans (MA) (n = 704) using a semi-structured diagnostic instrument.

RESULTS

Thirty percent (30%) of the sample reported ABD and 21% reported EABD. Those having had monthly ABD were more likely to be AI and have less education; those having had EABD were more likely to be AI, male, younger, have less education and lower economic status compared to participants without ABD. ABD/EABD was associated with higher impulsivity, a family history of AUD, and lower level of response to alcohol (ORs = 1.0-2.0), as well as with adult AUD (ORs = 3.7-48), other substance use disorders (ORs = 3.5-9), and conduct disorder/ antisocial personality disorder (ORs = 2.0-2.6), but not with anxiety/depression. Monthly EABD further increased the odds of AUD/SUD.

CONCLUSIONS

Although binge drinking was more common in AI compared to MA, there were little effects of race in individual risk factor analyses. Monthly ABD and EABD were common among these AI/MA as adolescents, and, as with other ethnic groups, these drinking patterns resulted in highly significant increases in the odds of developing alcohol and other substance use disorders in young adulthood.

Adolescent neuroimmune function and its interaction with alcohol

Adolescence is an evolutionarily conserved developmental period associated with behavioral change, including increased risk-taking and alcohol use. Experimentation with alcohol typically begins in adolescence and transitions to binge-like patterns of consumption. Alcohol exposure during adolescence can alter normative changes in brain structure and function. Understanding mechanisms by which ethanol impacts neurodevelopmental processes is important for preventing and ameliorating the deleterious consequences of adolescent alcohol abuse. This review focuses on the neuroimmune system as a key contributor to ethanol-induced changes in adolescent brain and behavior. After brief review of neuroimmune system development, acute and chronic effects of ethanol on adolescent neuroimmune functioning are addressed. Comparisons between stress/immunological challenges and ethanol on adolescent neuroimmunity are reviewed, as cross-sensitization is relevant during adolescence. The mechanisms by which ethanol alters neuroimmune functioning are then discussed, as they may portend development of neuropathological consequences and thus increase vulnerability to subsequent challenges and potentiate addictive behaviors.

The role of sex in the persistent effects of adolescent alcohol exposure on behavior and neurobiology in rodents

Alcohol drinking is often initiated during adolescence, and this frequently escalates to binge drinking. As adolescence is also a period of dynamic neurodevelopment, preclinical evidence has highlighted that some of the consequences of binge drinking can be long lasting with deficits persisting into adulthood in a variety of cognitive-behavioral tasks. However, while the majority of preclinical work to date has been performed in male rodents, the rapid increase in binge drinking in adolescent female humans has re-emphasized the importance of addressing alcohol effects in the context of sex as a biological variable. Here we review several of the consequences of adolescent ethanol exposure in light of sex as a critical biological variable. While some alcohol-induced outcomes, such as non-social approach/avoidance behavior and sleep disruption, are generally consistent across sex, others are variable across sex, such as alcohol drinking, sensitivity to ethanol, social anxiety-like behavior, and induction of proinflammatory markers.

Community Awareness of Outreach Efforts to Reduce Underage Drinking on California Indian Reservations

We report an evaluation of a combined individual- and community-level treatment and prevention effort to reduce underage drinking by American Indian (AI) youths on rural California Indian reservations. The interventions included: brief motivational interviewing and psychoeducation for Tribal youths, restricting alcohol sales to minors in alcohol sales outlets, and community mobilization and awareness activities. Surveys were collected from 120 adults and 74 teens to evaluate the awareness and effectiveness of the interventions. A high proportion of adult (93%) and youth (96%) respondents endorsed being aware of one or more of the intervention activities, and 88% of adults and 71% of youth felt the program impacted the community in a positive way. Eighty-four percent of adults and 63% of youth agreed that as a result of the activities that they decided to take action to reduce teen drinking in their community. Being aware of more of the intervention activities significantly increased the odds of taking action to change drinking behaviors. This study documents that a significant proportion of the community was aware of the intervention efforts and that awareness caused them to take action to reduce underage drinking. Such efforts may benefit other AI/AN communities seeking to reduce underage drinking.

Adolescent alcohol exposure increases orexin-A/hypocretin-1 in the anterior hypothalamus

Adolescence is a time of marked changes in sleep, neuromaturation, and alcohol use. While there is substantial evidence that alcohol disrupts sleep and that disrupted sleep may play a role in the development of alcohol use disorders (AUD), there is very little known about the brain mechanisms underlying this phenomenon. The orexin (also known as hypocretin) system is fundamental for a number of homeostatic mechanisms, including the initiation and maintenance of wakefulness that may be impacted by adolescent alcohol exposure. The current study investigated the impact of adolescent ethanol exposure on adult orexin-A/hypocretin-1 immunoreactive (orexin-A + IR) cells in hypothalamic nuclei in two models of adolescent intermittent ethanol (AIE) exposure. Both models assess adult hypothalamic orexin following either an AIE vapor exposure paradigm, or an AIE intragastric gavage paradigm during adolescence. Both AIE exposure models found that binge levels of ethanol intoxication during adolescence significantly increased adult orexin-A + IR expression in the anterior hypothalamic nucleus (AHN). Further, both AIE models found no change in orexin-A + IR in the posterior hypothalamic area (PH), perifornical nucleus (PeF), dorsomedial hypothalamic nucleus dorsal part (DMD) or lateral hypothalamic area (LH). However, AIE vapor exposure reduced orexin-A + IR in the paraventricular nucleus (PVN), but AIE gavage exposure did not. These findings suggest that the AHN orexinergic system is increased in adults following binge-like patterns of intoxication during adolescence. Altered adult AHN orexin could contribute to long-lasting changes in sleep.

Alcohol Sensitivity as an Endophenotype of Alcohol Use Disorder: Exploring Its Translational Utility between Rodents and Humans

Alcohol use disorder (AUD) is a complex, chronic, relapsing disorder with multiple interacting genetic and environmental influences. Numerous studies have verified the influence of genetics on AUD, yet the underlying biological pathways remain unknown. One strategy to interrogate complex diseases is the use of endophenotypes, which deconstruct current diagnostic categories into component traits that may be more amenable to genetic research. In this review, we explore how an endophenotype such as sensitivity to alcohol can be used in conjunction with rodent models to provide mechanistic insights into AUD. We evaluate three alcohol sensitivity endophenotypes (stimulation, intoxication, and aversion) for their translatability across human and rodent research by examining the underlying neurobiology and its relationship to consumption and AUD. We show examples in which results gleaned from rodents are successfully integrated with information from human studies to gain insight in the genetic underpinnings of AUD and AUD-related endophenotypes. Finally, we identify areas for future translational research that could greatly expand our knowledge of the biological and molecular aspects of the transition to AUD with the broad hope of finding better ways to treat this devastating disorder.

Delta Event-Related Oscillations Are Related to a History of Extreme Binge Drinking in Adolescence and Lifetime Suicide Risk

Alcohol exposure typically begins in adolescence, and heavy binge drinking is associated with health risk behaviors. Event-related oscillations (EROs) may represent sensitive biomarkers or endophenotypes for early alcohol exposure as well as other risk behaviors such as suicidal thoughts and actions. In this study, young adults (age 18–30 years) of American Indian (AI) (n = 479) and Mexican American (MA) (n = 705) ancestry were clinically assessed, and EROs were generated to happy, sad and neutral faces. Extreme adolescent binge drinking (10+ drinks) was common (20%) in this population of AI/MA and associated with a significantly increased risk of a lifetime history of suicidal acts (SA, suicide attempts, deaths) but not suicidal thoughts (ST, ideation, plans). ST were reported among MA participants, whereas SA were more common among AI young adults. Extreme adolescent binge drinking was also associated with errors in detection of sad and neutral faces, increases in delta ERO energy, and decreases in phase locking (PL), particularly in parietal areas. A lifetime history of ST was associated with increases in delta ERO energy and PL, whereas SA were associated with decreases in both. These studies suggest that ERO measures may represent important potential biomarkers of adolescent extreme binge drinking and risk for suicidal behaviors.

PSPH-D-18-00526: Effect of a dual orexin receptor antagonist (DORA-12) on sleep and event-related oscillations in rats exposed to ethanol vapor during adolescence

RATIONALE

Sleep difficulties are one of the problems associated with adolescent binge drinking. However, the mechanisms underlying adolescent alcohol-associated sleep disturbances and potential targets for therapy remain under investigated. Orexin receptor antagonists may have therapeutic value in the treatment of insomnia, yet the use of this class of drugs in the treatment of sleep disturbances following adolescent alcohol exposure has not been studied.

OBJECTIVES

This study employed a model whereby ethanol vapor exposure occurred for 5 weeks during adolescence (AIE), and waking event-related oscillations (EROs) and EEG sleep were subsequently evaluated in young adult rats. The ability of two doses (10, 30 mg/kg PO) of a dual orexin receptor antagonist (DORA-12) to modify sleep, EEG, and EROs was investigated in AIE rats and controls.

RESULTS

Adolescent vapor exposure was found to produce a fragmentation of sleep, in young adults, that was partially ameliorated by DORA-12. DORA-12 also produced increases in delta and theta power in waking EROs recorded before sleep, and deeper sleep as indexed by increases in delta and theta power in the sleep EEG in both ethanol and control rats. Rats given DORA-12 also fell asleep faster than vehicle-treated rats as measured by a dose-dependent reduction in the latency to both the first slow wave and REM sleep episodes.

CONCLUSIONS

This study showed that DORA-12 can affect the sleep disturbance that is associated with a history of adolescent ethanol exposure and also has several other sleep-promoting effects that are equivalent in both ethanol and control rats.

Adolescent Intermittent Ethanol Exposure Effects on Kappa Opioid Receptor Mediated Dopamine Transmission: Sex and Age of Exposure Matter

Underage alcohol drinking increases the risk of developing alcohol use disorder (AUD). In rodents, adolescent ethanol exposure augments ethanol consumption and anxiety-like behavior while reducing social interaction. However, the underlying mechanisms driving these adaptations are unclear. The dopamine and kappa opioid receptor (KOR) systems in the nucleus accumbens (NAc) are implicated in affective disorders, including AUD, with studies showing augmented KOR function and reduced dopamine transmission in ethanol-dependent adult animals. Thus, here we examine the impact of adolescent intermittent ethanol (AIE) exposure on dopamine transmission and KOR function in the NAc. Rats were exposed to water or ethanol (4 g/kg, intragastrically) every other day during early (postnatal day (PD) 25–45) or late (PD 45–65) adolescence. While AIE exposure during early adolescence (early-AIE) did not alter dopamine release in male and female rats, AIE exposure during late adolescence (late-AIE) resulted in greater dopamine release in males and lower dopamine release in females. To determine the impact of AIE on KOR function, we measured the effect of KOR activation using U50,488 (0.01–1.00 µM) on dopamine release. Early-AIE exposure potentiated KOR-mediated inhibition of dopamine release in females, while late-AIE exposure attenuated this effect in males. Interestingly, no differences in KOR function were observed in early-AIE exposed males and late-AIE exposed females. Together, these data suggest that AIE exposure impact on neural processes is dependent on sex and exposure timing. These differences likely arise from differential developmental timing in males and females. This is the first study to show changes in KOR function following AIE exposure.

Adolescent Ethanol Exposure: Anxiety-Like Behavioral Alterations, Ethanol Intake, and Sensitivity

Adolescence is a developmental period associated with rapid age-specific physiological, neural, and hormonal changes. Behaviorally, human adolescents are characterized by age-typical increases in novelty-seeking and risk-taking, including the frequent initiation of alcohol and drug use. Alcohol use typically begins during early adolescence, and older adolescents often report high levels of alcohol consumption, commonly referred to as high-intensity drinking. Early-onset and heavy drinking during adolescence are associated with an increased risk of developing alcohol use disorders later in life. Yet, long-term behavioral consequences of adolescent alcohol use that might contribute to excessive drinking in adulthood are still not well understood. Recent animal research, however, using different exposure regimens and routes of ethanol administration, has made substantial progress in identifying the consequences of adolescent ethanol exposure that last into adulthood. Alterations associated with adolescent ethanol exposure include increases in anxiety-like behavior, impulsivity, risk-taking, and ethanol intake, although the observed alterations differ as a function of exposure regimens and routes of ethanol administration. Rodent studies have also shown that adolescent ethanol exposure produces alterations in sensitivity to ethanol, with these alterations reminiscent of adolescent-typical ethanol responsiveness. The goal of this mini-review article is to summarize the current state of animal research, focusing on the long-term consequences related to adolescent ethanol exposure, with a special emphasis on the behavioral alterations and changes to ethanol sensitivity that can foster high levels of drinking in adulthood.

Phase locking of event-related oscillations is decreased in both young adult humans and rats with a history of adolescent alcohol exposure

Alcohol exposure typically begins in adolescence, and frequent binge drinking has been associated with health risk behaviors including alcohol use disorders (AUDs). Few studies have documented the effects of a history of adolescent binge drinking on neurophysiological consequences in young adulthood. Synchrony of phase (phase locking (PL)) of event-related oscillations (EROs) within and between different brain areas reflects communication exchange between neural networks and is a sensitive measure of adolescent development in both rats and humans, and thus may be a good translational measure of the potential harmful effects of alcohol exposure during adolescence. In this study, EROs were collected from 1041 young adults of Mexican American and American Indian ancestry (age 18-30 years) with and without a history of adolescent binge drinking (five drinks for boys and four for girls per occasion at least once per month) and in 74 young adult rats with and without a history of 5 weeks of adolescent alcohol vapor exposure. PL of theta and beta frequencies between frontal and parietal cortex were estimated using an auditory-oddball paradigm in the rats and a visual facial expression paradigm in the humans. Significantly lower PL between frontal and parietal cortices in the theta frequencies was seen in both the humans and the rats with a history of adolescent alcohol exposure as compared with their controls. These findings suggest that alcohol exposure during adolescence may result in decreases in synchrony between cortical neuronal networks, suggesting a developmental delay, in young adult humans and in rats.

Time Course of Blood and Brain Cytokine/Chemokine Levels Following Adolescent Alcohol Exposure and Withdrawal in Rats

BACKGROUND

Adolescence is a critical period for neural development, and alcohol exposure during adolescence can lead to an elevated risk for health consequences as well as alcohol use disorders. Clinical and experimental data suggest that chronic alcohol exposure may produce immunomodulatory effects that can lead to the activation of pro-inflammatory cytokine pathways as well as microglial markers. The present study evaluated, in brain and blood, the effects of adolescent alcohol exposure and withdrawal on microglia and on the most representative pro- and anti-inflammatory cytokines and major chemokines that can contribute to the establishing of a neuroinflammatory environment.

METHODS

Wistar rats (males, n = 96) were exposed to ethanol (EtOH) vapors, or air control, for 5 weeks over adolescence (PD22-PD58). Brains and blood samples were collected at 3 time points: (i) after 35 days of vapor/air exposure (PD58); (ii) after 1 day of withdrawal (PD59), and (iii) 28 days after withdrawal (PD86). The ionized calcium-binding adapter molecule 1 (Iba-1) was used to index microglial activation, and cytokine/chemokine responses were analyzed using magnetic bead panels.

RESULTS

After 35 days of adolescent vapor exposure, a significant increase in Iba-1 immunoreactivity was seen in amygdala, frontal cortex, hippocampus, and substantia nigra. However, Iba-1 density returned to control levels at both 1 day and 28 days of withdrawal except in the hippocampus where Iba-1 density was significantly lower than controls. In serum, adolescent EtOH exposure induced a reduction in IL-13 and an increase in fractalkine at day 35. After 1 day of withdrawal, IL-18 was reduced, and IP-10 was elevated, whereas both IP-10 and IL-10 were elevated at 28 days following withdrawal. In the frontal cortex, adolescent EtOH exposure induced an increase in IL-1β at day 35, and 28 days of withdrawal, and IL-10 was increased after 28 days of withdrawal.

CONCLUSION

These data demonstrate that EtOH exposure during adolescence produces significant microglial activation; however, inflammatory markers seen in the blood appear to differ from those observed in the brain.

Effects of chronic intermittent ethanol exposure during early and late adolescence on anxiety-like behaviors and behavioral flexibility in adulthood

Although both humans and laboratory rodents demonstrate cognitive and affective alterations associated with adolescent alcohol exposure, it is still unknown whether the consequences of early initiation of alcohol use differ from those of later binge drinking within the adolescent developmental period. The present study was designed to assess the effects of early and late AIE on (1) anxiety-like behavior under social (modified social interaction test) and non-social test circumstances (modified light/dark box test, elevated plus maze), and (2) behavioral flexibility, indexed via set shifting in males and females. Early-mid adolescent intermittent exposure (early AIE) occurred between postnatal days (P) 25 and 45, whereas late adolescent intermittent exposure (late AIE) was conducted between P45 and P65, with behavioral testing initiated not earlier than 25 days after repeated exposure to ethanol (4.0 g/kg intragastrically, every other day for a total of 11 exposures). Anxiety-like behavior on the EPM was evident in males and females following early AIE, whereas only males demonstrated non-social anxiety on the EPM following late AIE. Social anxiety-like alterations and deficits in behavioral flexibility were evident only in males following early AIE. Taken together, the results of the present study demonstrate a particular vulnerability of young adolescent males to long-lasting detrimental effects of repeated ethanol and an insensitivity of older adolescent females to the intermittent ethanol exposure paradigm.

From adolescence to late aging: A comprehensive review of social behavior, alcohol, and neuroinflammation across the lifespan

The passage of time dictates the pace at which humans and other organisms age but falls short of providing a complete portrait of how environmental, lifestyle and underlying biological processes contribute to senescence. Two fundamental features of the human experience that change dramatically across the lifespan include social interactions and, for many, patterns of alcohol consumption. Rodent models show great utility for understanding complex interactions among aging, social behavior and alcohol use and abuse, yet little is known about the neural changes in late aging that contribute to the natural decline in social behavior. Here, we posit that aging-related neuroinflammation contributes to the insipid loss of social motivation across the lifespan, an effect that is exacerbated by patterns of repeated alcohol consumption observed in many individuals. We provide a comprehensive review of (i) neural substrates crucial for the expression of social behavior under non-pathological conditions; (ii) unique developmental/lifespan vulnerabilities that may contribute to the divergent effects of low-and high-dose alcohol exposure; and (iii) aging-associated changes in neuroinflammation that may sit at the intersection between social processes and alcohol exposure. In doing so, we provide an overview of correspondence between lifespan/developmental periods between common rodent models and humans, give careful consideration to model systems used to aptly probe social behavior, identify points of coherence between human and animal models, and point toward a multitude of unresolved issues that should be addressed in future studies. Together, the combination of low-dose and high-dose alcohol effects serve to disrupt the normal development and maintenance of social relationships, which are critical for both healthy aging and quality of life across the lifespan. Thus, a more complete understanding of neural systems-including neuroinflammatory processes-which contribute to alcohol-induced changes in social behavior will provide novel opportunities and targets for promoting healthy aging.

Adolescent intermittent ethanol exposure: Effects on pubertal development, novelty seeking, and social interaction in adulthood

Alcohol use initiated early in adolescence is a major predictor for the development of alcohol use disorders. This risk may be increased when drinking is initiated around the time of puberty, given evidence of bidirectional relationships between alcohol and gonadal hormones. The current study examined the effects of adolescent intermittent ethanol exposure (AIE) on pubertal timing and expression of novelty-seeking and peer-directed behaviors as well as neural correlates of these behaviors. AIE did not affect pubertal timing or the later expression of novelty-seeking and peer-directed behaviors. AIE increased corticosterone (CORT) levels in females not tested behaviorally in adulthood or tested in the novel-object exploration paradigm, whereas social interaction blunted CORT levels in AIE females. Delays in pubertal timing and decreases in CORT levels were correlated, however, with increased novelty seeking in adult males - a phenotype associated with increased addiction vulnerability. In females, social testing elevated oxytocin receptor (OXTR) mRNA expression in the central amygdala (CeA), with this social testing-associated elevation evident in the lateral septum (LS), regardless of sex. Vasopressin receptor 1a (AVP-1aR) mRNA expression in the CeA was enhanced by social testing in females, but not males, with expression of this gene suppressed by social testing in the LS in males, but not females. Together, these data demonstrate that behavioral and neural alterations that may serve as risk factors in later drug vulnerabilities are likely not the result of a single insult, but may reflect interactions among several variables including sex, pubertal timing, stress reactivity, and test circumstances.

Comparison of age of first drink and age of first intoxication as predictors of substance use and mental health problems in adulthood

BACKGROUND

International public policy on age of first alcoholic drink (AFD) has emphasised the long-term benefits of delaying AFD. This study aimed to compare AFD to age of first intoxication (AFI) as predictors of substance use disorder and mental disorder outcomes in adulthood.

METHODS

Data were obtained from a longitudinal birth cohort in Christchurch, New Zealand. Participants were born in 1977. Analysis samples ranged from n = 1025 (age 18) to n = 962 (age 35). Measures of AFD and AFI were generated using parental- and self-report data collected from age 11. Outcomes at age 18-35 were alcohol quantity consumed, DSM-IV alcohol use disorder (AUD) and AUD symptoms, major depression, anxiety disorder, and nicotine, cannabis, and other illicit drug dependence. Covariate factors measured during childhood included family socioeconomic status, family functioning, parental alcohol-related attitudes/behaviours, and individual factors.

RESULTS

There was a significant unadjusted association between AFD and symptoms of AUD (p < .001) and nicotine dependence (p < .05) but not other outcomes. AFI was significantly (p < .05) associated with all outcomes. After adjustment for covariates, the association between AFD and outcomes was not statistically significant. Conversely, in adjusted models, statistically significant (p < .05) associations remained between AFI and all AUD and substance use disorder outcomes but not alcohol consumption or mental disorder outcomes.

CONCLUSIONS

AFI was a more robust predictor of adult substance use disorder outcomes than AFD. Public health and policy interventions aimed at prevention of long term harms from alcohol should therefore focus on AFI rather than AFD.

Intermittent voluntary ethanol consumption combined with ethanol vapor exposure during adolescence increases drinking and alters other behaviors in adulthood in female and male rats

Epidemiological studies suggest that binge drinking is prevalent among adolescents, and may result in neurobehavioral consequences. Animal models provide the experimental control to investigate the consequences of "binge" alcohol exposure during this neurodevelopmental epoch. The current study used an animal model that combined an intermittent pattern of alcohol vapor exposure with voluntary drinking of 20% unsweetened alcohol in adolescent male and female Wistar rats (postnatal day [PD] 22-62), in order to test for potential differences in behavioral changes, ethanol drinking, and hypocretin/orexin (Hcrt/OX) signaling associated with exposure status. Two weeks after discontinuation of the alcohol vapor exposure and drinking during adolescence, rats were tested in adulthood for anxiety-like behaviors using a modified open-field conflict task, pre-pulse facilitation of startle response, light/dark box, and marble burying test. Adolescent alcohol exposure led to overall decreased startle response and increased behavioral arousal in the light/dark chamber during adulthood. Additionally, male rats demonstrated more disinhibited behavior during the conflict task compared to females, and female rats exhibited more rearing behavior during the light/dark test. Rats were also given a 2-bottle choice test that resulted in adolescent alcohol-exposed rats drinking significantly more alcohol in adulthood. Further, female rats also consumed more alcohol in adulthood compared to males. Estrous cycle phase did not account for any of the sex differences observed in the behavioral measures. Histological results indicated that adolescent alcohol did not alter Hcrt/OX-1 or Hcrt/OX-2 receptor mRNA expression levels in adult rats compared to control adults. However, female rats expressed a higher level of Hcrt/OX-1 and Hcrt/OX-2 receptor mRNA in the frontal cortex compared to males. These data suggest that our current model of intermittent ethanol exposure in adolescence can modestly affect both behavior and future consumption of alcohol and that Hcrt/OX receptor signaling differs between males and females.

Oxytocin and vasopressin modulation of social anxiety following adolescent intermittent ethanol exposure

RATIONALE

Adolescent intermittent ethanol exposure (AIE) produces lasting, sex-specific social anxiety-like alterations in male, but not female rats. Oxytocin (OXT) and vasopressin (AVP) brain systems play opposite roles in regulating social preference/avoidance, with OXT increasing approach to, and AVP increasing avoidance of social stimuli.

OBJECTIVES

To test the hypothesis that social anxiety-like alterations seen in adult males after AIE are associated with a shift in the balance between OXT and AVP toward AVP, effectiveness of pharmacological activation of the OXT system and blockade of endogenous activity at AVP receptors for reversing AIE-induced social anxiety-like alterations was assessed, along with examination of the effects of AIE on OXT, vasopressin V1a, and V1b receptor (OXT-R, V1a-R, and V1b-R) surface expression in the hypothalamus.

METHODS

Sprague-Dawley male and female rats were given 4 g/kg ethanol (AIE) or water intragastrically every 48 h for a total of 11 exposures during postnatal days (P) 25-45. On P70-72, animals were given a social interaction test following administration of a selective OXT-R agonist WAY-267464, selective V1a-R antagonist SR-49059, or V1b-R antagonist SSR-149415, and hypothalamic tissue was collected.

RESULTS

Social anxiety-like behavior was induced by AIE in males but not females, and was selectively reversed by the selective OXT-R agonist and V1b-R antagonist, but not V1a-R antagonist. AIE was also found to decrease OXT-R, but increase V1b-R neuronal surface expression relative to water-exposed controls in the hypothalamus of males, but not females.

CONCLUSIONS

These findings demonstrate that AIE induces changes in OXT-R and AVP-R surface expression in the hypothalamus along with social anxiety-like alterations in male rats. These social anxiety-like alterations can be reversed either by activation of the OXT system or by suppression of the AVP system, data that support the hypothesis that social anxiety-like alterations induced by adolescent alcohol exposure in male rats are associated at least in part with an OXT/AVP imbalance.

Prevention of Underage Drinking on California Indian Reservations Using Individual- and Community-Level Approaches

OBJECTIVES

To evaluate combined individual- and community-level interventions to reduce underage drinking by American Indian/Alaska Native (AI/AN) youths on rural California Indian reservations.

METHODS

Individual-level interventions included brief motivational interviewing and psychoeducation for Tribal youths. Community-level interventions included community mobilization and awareness activities, as well as restricting alcohol sales to minors. To test effects, we compared 7 waves of California Healthy Kids Survey data (2002-2015) for 9th- and 11th-grade AI/AN and non-AI/AN students in intervention area schools with California AI/AN students outside the intervention area (n = 617, n = 33 469, and n = 976, respectively).

RESULTS

Pre- to postintervention mean past 30-day drinking frequency declined among current drinkers in the intervention group (8.4-6.3 days) relative to comparison groups. Similarly, heavy episodic drinking frequency among current drinkers declined in the intervention group (7.0-4.8 days) versus the comparison groups.

CONCLUSIONS

This study documented significant, sustained past 30-day drinking or heavy episodic drinking frequency reductions among AI/AN 9th- and 11th-grade current drinkers in rural California Indian reservation communities exposed to multilevel interventions. Public Health Implications. Multilevel community-partnered interventions can effectively reduce underage alcohol use in this population.

A history of binge drinking during adolescence is associated with poorer sleep quality in young adult Mexican Americans and American Indians

RATIONALE

Binge drinking during adolescence is common, and adolescents and young adults with alcohol problems may also have sleep difficulties. However, few studies have documented the effects of a history of adolescent binge drinking on sleep in young adulthood in high-risk minority populations.

OBJECTIVES

To quantify sleep disturbance, as indexed by the Pittsburgh Sleep Quality Index (PSQI), in a sample of young adult Mexican American and American Indian men and women (18-30 years, n = 800) with and without a history of alcohol binge drinking during adolescence, controlling for age, gender, and race.

RESULTS

Gender was found to affect PSQI responses with females reporting waking up at night, having more bad dreams, and later habitual bedtimes than males, and males reporting more problems with breathing and snoring. Increasing age was associated with snoring or coughing, less hours spent in bed, and later evening bedtimes. Race also influenced the PSQI with American Indians reporting longer sleep latencies and sleep durations, more hours spent in bed, and more trouble with coughing and snoring than Mexican Americans, and Mexican Americans reporting later bedtimes. A history of adolescent regular binge drinking was associated with longer sleep latencies, more problems with breathing, bad dreams, and an overall higher PSQI total score, when controlling for age, race, and gender.

CONCLUSIONS

This report suggests, like what has been found in young adults in general population samples, that binge drinking during adolescence is associated with deleterious consequences on sleep quality in young adulthood in these high-risk and understudied ethnic groups.

Effect of gabapentin on sleep and delta and theta EEG power in adult rats exposed to chronic intermittent ethanol vapor and protracted withdrawal during adolescence

RATIONALE

Adolescents and young adults with alcohol problems may also have sleep difficulties. However, whether these sleep problems are a result of a history of drinking or arise due to other comorbid disorders is difficult to disentangle in human studies. Additionally, the mechanisms underlying adolescent alcohol-induced sleep disturbances and potential targets for therapy also remain under-investigated. Recent clinical trials have demonstrated that the anticonvulsant and analgesic drug gabapentin may have therapeutic value in normalizing sleep quality in adult recovering alcoholics, yet its potential for the treatment of adolescent sleep disturbances has not been investigated.

OBJECTIVES

This study sought to evaluate the effects of a history of 5 weeks of chronic intermittent ethanol vapor exposure, administered during adolescence (AIE), on EEG sleep, in young adult rats (n = 29). The ability of two doses of gabapentin (30, 120 mg/kg) to modify sleep and slow wave activity were also investigated in these young adult rats exposed to alcohol vapor during adolescence.

RESULTS

Adolescent vapor exposure in the rat was found to result in deficits in delta (1-4 Hz) and theta (4-8 Hz) power during slow wave sleep. Administration of gabapentin caused a "normalization" of the delta power deficits but did not affect theta power.

CONCLUSIONS

This report suggests that the potential mechanisms and therapeutic targets for sleep disturbance associated with adolescent alcohol exposure can be studied in preclinical models and that gabapentin may show partial efficacy in ameliorating these sleep deficits.

Religiosity as a possible protective factor against "binge drinking" among 12-year-old students: a population-based study

Associated with positive impacts on health, religiosity has presented itself as a possible protection factor against alcohol consumption by teenagers. This study evaluated the prevalence of binge drinking and its association with religiosity among 12-year-old students, from Diamantina, State of Minas Gerais. Statistical analyses involved chi-square Pearson (p < 0,05) and Poisson regression with robust variance. The sample included a census of 588 students. Participation in religious activities was associated with no binge drinking (PR = 0,823; 95% CI: 0,717 - 0,945); and consumption of alcoholic beverages by the best friend was associated with binge drinking (PR = 1.554; 95% CI: 1,411-1,711). It was concluded that religiosity was associated with no consumption of alcoholic beverages in binge drinking sessions.

A pilot randomized trial of Motivational Interviewing compared to Psycho-Education for reducing and preventing underage drinking in American Indian adolescents

Underage drinking is an important public health issue for American Indian and Alaska Native (AI/AN) adolescents, as it is for U. S. teens of all ethnicities. One of the demonstrated risk factors for the development of alcohol use disorders in AI/AN is early age of initiation of drinking. To address this issue a randomized trial to assess the efficacy of Motivational Interviewing (MI) compared to Psycho-Education (PE) to reduce and prevent underage drinking in AI/AN youth was developed and implemented. Sixty-nine youth received MI or PE and 87% were assessed at follow-up. For teens who were already drinking, participating in the intervention (MI or PE) was associated, at follow-up, with lower quantity×frequency (q×f) of drinking (p=0.011), fewer maximum drinks per drinking occasion (p=0.004), and fewer problem behaviors (p=0.009). The MI intervention resulted in male drinkers reporting a lower q×f of drinking (p=0.048) and female drinkers reporting less depression (p=0.011). In teens who had not started drinking prior to the intervention, 17% had initiated drinking at follow-up. As a group they reported increased quantity×frequency of drinking (p=0.008) and maximum drinks (p=0.047), but no change in problem behaviors. These results suggest that intervening against underage drinking using either MI or PE in AI/AN youth can result in reduced drinking, prevention of initiation of drinking, and other positive behavioral outcomes. Brief interventions that enhance motivation to change as well as Psycho-Education may provide a successful approach to reducing the potential morbidity of underage drinking in this high-risk group.

Ethanol Sensitization during Adolescence or Adulthood Induces Different Patterns of Ethanol Consumption without Affecting Ethanol Metabolism

In previous study, we demonstrated that ethanol preexposure may increase ethanol consumption in both adolescent and adult mice, in a two-bottle choice model. We now questioned if ethanol exposure during adolescence results in changes of consumption pattern using a three-bottle choice procedure, considering drinking-in-the-dark and alcohol deprivation effect as strategies for ethanol consumption escalation. We also analyzed aldehyde dehydrogenase (ALDH) activity as a measurement of ethanol metabolism. Adolescent and adult Swiss mice were treated with saline (SAL) or 2.0 g/kg ethanol (EtOH) during 15 days (groups: Adolescent-SAL, Adolescent-EtOH, Adult-SAL and Adult-EtOH). Five days after the last injection, mice were exposed to the three-bottle choice protocol using sucrose fading procedure (4% + sucrose vs. 8%–15% ethanol + sucrose vs. water + sucrose) for 2 h during the dark phase. Sucrose was faded out from 8% to 0%. The protocol was composed of a 6-week acquisition period, followed by four withdrawals and reexposures. Both adolescent and adult mice exhibited ethanol behavioral sensitization, although the magnitude of sensitization in adolescents was lower than in adults. Adolescent-EtOH displayed an escalation of 4% ethanol consumption during acquisition that was not observed in Adult-EtOH. Moreover, Adult-EtOH consumed less 4% ethanol throughout all the experiment and less 15% ethanol in the last reexposure period than Adolescent-EtOH. ALDH activity varied with age, in which older mice showed higher ALDH than younger ones. Ethanol pretreatment or the pattern of consumption did not have influence on ALDH activity. Our data suggest that ethanol pretreatment during adolescence but not adulthood may influence the pattern of ethanol consumption toward an escalation in ethanol consumption at low dose, without exerting an impact on ALDH activity.

Alcohol drinking during adolescence increases consumptive responses to alcohol in adulthood in Wistar rats

Binge drinking and the onset of alcohol-use disorders usually peak during the transition between late adolescence and early adulthood, and early adolescent onset of alcohol consumption has been demonstrated to increase the risk for alcohol dependence in adulthood. In the present study, we describe an animal model of early adolescent alcohol consumption where animals drink unsweetened and unflavored ethanol in high concentrations (20%). Using this model, we investigated the influence of drinking on alcohol-related appetitive behavior and alcohol consumption levels in early adulthood. Further, we also sought to investigate whether differences in alcohol-related drinking behaviors were specific to exposure in adolescence versus exposure in adulthood. Male Wistar rats were given a 2-bottle choice between 20% ethanol and water in one group and between two water bottles in another group during their adolescence (Postnatal Day [PD] 26-59) to model voluntary drinking in adolescent humans. As young adults (PD85), rats were trained in a paradigm that provided free access to 20% alcohol for 25 min after completing up to a fixed-ratio (FR) 16 lever press response. A set of young adult male Wistar rats was exposed to the same paradigm using the same time course, beginning at PD92. The results indicate that adolescent exposure to alcohol increased consumption of alcohol in adulthood. Furthermore, when investigating differences between adolescent high and low drinkers in adulthood, high consumers continued to drink more alcohol, had fewer FR failures, and faster completion of FR schedules in adulthood, whereas the low consumers were no different from controls. Rats exposed to ethanol in young adulthood also increased future intake, but there were no differences in any other components of drinking behavior. Both adolescent- and adult-exposed rats did not exhibit an increase in lever pressing during the appetitive challenge session. These data indicate that adolescent and early adult alcohol exposure can increase consumptive aspects of drinking but that adolescent exposure may preferentially influence the motivation to drink.

Clinical characteristics of alcohol combined with other substance use disorders in an American Indian community sample

BACKGROUND

Alcohol and other substance use disorders (SUD) pose major problems of morbidity and mortality in some American Indian communities, but little is known about the clinical characteristics, risk factors, and consequences of combined alcohol and other substance use disorders (multi-substance use disorder, MSUD) in those communities.

METHODS

Using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), in a community sample of 876 American Indians, the clinical characteristics of lifetime DSM-5 moderate or severe alcohol use disorder alone (AUD alone) (n=146) and MSUD (defined as alcohol and ≥1 other SUD) (n=284) were evaluated and compared to 347 participants with no lifetime SUD (no SUD).

RESULTS

The majority (57%) of participants with a SUD had multi-substance use disorder and 94% of those were with AUD. Stimulants (cocaine and/or amphetamine) and/or cannabis were the most common other SUDs. Participants with AUD alone were more likely to be male and have an earlier age of first alcohol intoxication than those with no SUD. Those with MSUD were more likely to have dropped out of high school, have antisocial personality disorder (ASPD) or conduct disorder (CD), have earlier ages of first alcohol intoxication and first use of cannabis and stimulants, an earlier age of onset of AUD, and more of several AUD symptoms than those with AUD alone, but the same temporal course and time to remission of AUD.

CONCLUSIONS

MSUD is prevalent in this sample, is associated with multiple comorbidities and denotes a more severe alcohol syndrome than AUD alone.

Some thoughts about the epidemiology of alcohol and drug use among American Indian/Alaska Native populations

Researchers have established that rates of alcohol and illicit drug use among American Indians/Alaska Natives vary by tribe, gender, and age group, making it difficult to get an accurate estimate of the actual extent of the problem of substance abuse within this population group. Although percentage rates of alcohol consumption are higher in non-Hispanic Whites, American Indians/Alaska Natives nevertheless have the highest alcohol-related mortality rates and rates of substance use and dependence of all ethnic groups. Alcohol-related motor vehicle accidents are especially high for American Indian/Alaska Natives. Similarly, illicit drug use is higher among American Indians/Alaska Natives across all age groups compared to non-Indians. Data indicate that American Indians/Alaska Natives have the highest rates of use for marijuana, cocaine, inhalants, hallucinogens, and non-medical use of psychotherapeutics compared to other ethnic groups. Anecdotally, use of amphetamine appears to be high within some American Indian/Alaska Native tribes and has become a serious concern for most American Indian/Alaska Native communities. The percentage of American Indian/Alaska Native women using illicit drugs is lower than that found in men, except in younger age groups, in which percentage rates of illicit drug use by women in some tribes are comparable to rates for men.

Alcohol Expectancies Mediate the Relationship Between Age of First Intoxication and Drinking Outcomes in College Binge Drinkers

BACKGROUND

While prior research has shown that age of first intoxication (AI) is associated with negative alcohol outcomes, limited research has examined factors accounting for this relationship. Alcohol expectancies, or beliefs about the effects of alcohol, may explain such associations as both positive and negative expectancies have been shown to be key predictors of drinking outcomes.

OBJECTIVE

The present study examined expectancies as mediators between early AI and alcohol-related outcomes.

METHOD

Data collection occurred in 2012 and 2013. Participants were college students (N = 562, 65.8% women) who completed an online survey including measures of alcohol use history, alcohol expectancies, typical alcohol consumption, and alcohol-related problems. Structural equation modeling was used to test the hypothesized model.

RESULTS

Our findings support a model whereby AI is associated with drinking through its influence on both positive and negative expectancies. Specifically, an earlier AI was associated with stronger alcohol expectancies, which in turn, was associated with heavier alcohol use and alcohol-related problems.

CONCLUSIONS/IMPORTANCE

These findings are consistent with expectancy theory and previous research suggesting that more experienced drinkers hold stronger drinking-related beliefs, be it positive or negative, and these expectancies ultimately explain variability in alcohol use and problems. Our findings further support that expectancies play an important role in the initiation of drinking behavior.

The clinical course of DSM-5 alcohol use disorders in young adult native and Mexican Americans

BACKGROUND AND OBJECTIVES

To determine if the clinical course of DSM-5 alcohol use disorders (AUD) in select populations of young adults (18-30 years) differed based on gender, diagnostic severity (mild, moderate, severe), and ethnicity.

METHODS

Native Americans (NA) and Mexican Americans (MA) (n = 1,129) were recruited from the community and completed a structured diagnostic interview. Participants with DSM-5 AUDs were compared based on gender, severity of the disorder (mild, moderate, severe), and ethnicity for differences in drinking levels, as well as the clinical course of AUD as defined by the occurrence and sequence of 36 alcohol-related life events.

RESULTS

Seventy percent of the NA men, 64% of the NA women, 56% of the MA men, and 42% of the MA women met lifetime diagnostic criteria for a DSM-5 AUD. NA reported more alcohol-related life events and at an earlier age than MA. A high degree of similarity in the clinical course was found between men and women and between those with severe or moderate disorder, but not with those with mild disorder.

CONCLUSIONS

NA had higher drinking levels and more alcohol problems at an earlier age than MA. A similar clinical course was seen based on gender and ethnicity in these young adults, but not based on diagnostic severity.

SCIENTIFIC SIGNIFICANCE

The DSM-5 mild AUD category differs from the moderate and severe categories on drinking history, clinical course, gender, and ethnic distribution. Mild AUD may not be in the same clinical continuum as moderate and severe AUD in these populations.

Chronic intermittent ethanol exposure produces persistent anxiety in adolescent and adult rats

BACKGROUND

Ethanol (EtOH) dependence and tolerance in the adult are marked by increased function of NMDA receptors and decreased function of GABAA receptors, which coincide with altered receptor subunit expression in specific brain regions. Adolescents often use EtOH at levels greater than adults, yet the receptor subunit expression profiles following chronic intermittent EtOH (CIE) exposure in adolescents are not known. Persistent age-dependent changes in receptor subunit alterations coupled with withdrawal-related anxiety may help explain the increase in alcohol abuse following adolescent experimentation with the drug.

METHODS

Adolescent and adult rats received 10 intraperitoneal administrations of 4.0 g/kg EtOH or saline every 48 hours. At either 24 hours or 12 days after the final exposure, anxiety-like behavior was assessed on the elevated plus maze and tissue was collected. Western blotting was used to assess changes in selected NMDA and GABAA receptor subunits in whole cortex and bilateral hippocampus.

RESULTS

CIE exposure yields a persistent increase in anxiety-like behavior in both age groups. However, selected NMDA and GABAA receptor subunits were not differentially altered by this CIE exposure paradigm in adolescents or adults.

CONCLUSIONS

CIE exposure produced persistent anxiety-like behavior, which has important implications for alcohol cessation. Given the reported behavioral and neuropeptide expression changes in response to this dose of EtOH, it is important for future work to consider the circumstances under which these measures are altered by EtOH exposure.

Low voltage alpha EEG phenotype is associated with reduced amplitudes of alpha event-related oscillations, increased cortical phase synchrony, and a low level of response to alcohol

Low voltage EEG (LVEEG) is a heritable phenotype that differs depending on ancestral heritage, yet its impact on brain networks and cognition remain relatively unexplored. In this study we assessed energy and task related phase locking of event-related oscillation (EROs), behavioral responses, measures of IQ and personality, and expected responses to alcohol in a large sample of individuals with LVEEG compared to those with higher voltage variants. Participants (n=762) were recruited from a Native American community and completed a diagnostic interview, the Quick Test, the Subjective High Assessment Scale Expectation Version (SHAS-E) and the Maudsley Personality Inventory. Clinical and spectral analyzed EEGs were collected for determination of the presence of a LVEEG variant. EROs were generated using a facial expression recognition task. Participants with LVEEG (n=451) were significantly more likely to be older, married and have higher degrees of Native American heritage but did not differ in gender, income or education. Individuals with LVEEG were also found to have decreased energy in their alpha EROs, increased phase locking between stimulus trials, and increased phase-locking between cortical brain areas. No significant differences in the cognitive tests, personality variables or alcohol dependence or anxiety diagnoses were found, however, individuals with LVEEG did report a larger number of drinks ever consumed in a 24-h period and a less intense expected response to alcohol. These data suggest that alpha power in the resting EEG is highly associated with energy and cortical connectivity measures generated by event-related stimuli, as well as potentially increased risk for alcohol use.

Asian American problem drinking trajectories during the transition to adulthood: ethnic drinking cultures and neighborhood contexts

OBJECTIVES

We aimed to identify problem drinking trajectories and their predictors among Asian Americans transitioning from adolescence to adulthood. We considered cultural and socioeconomic contextual factors, specifically ethnic drinking cultures, neighborhood socioeconomic status, and neighborhood coethnic density, to identify subgroups at high risk for developing problematic drinking trajectories.

METHODS

We used a sample of 1333 Asian Americans from 4 waves of the National Longitudinal Study of Adolescent to Adult Health (1994-2008) in growth mixture models to identify trajectory classes of frequent heavy episodic drinking and drunkenness. We fitted multinomial logistic regression models to identify predictors of trajectory class membership.

RESULTS

Two dimensions of ethnic drinking culture-drinking prevalence and detrimental drinking pattern in the country of origin-were predictive of problematic heavy episodic drinking and drunkenness trajectories. Higher neighborhood socioeconomic status in adolescence was predictive of the trajectory class indicating increasing frequency of drunkenness. Neighborhood coethnic density was not predictive of trajectory class membership.

CONCLUSIONS

Drinking cultures in the country of origin may have enduring effects on drinking among Asian Americans. Further research on ethnic drinking cultures in the United States is warranted for prevention and intervention.

Off-premise alcohol outlets on and around tribal land: risks for rural California Indian youth

Investigating the alcohol environment for rural American Indian youth, we conducted 70 interviews with leading members and youth representatives of nine Southern California tribes. We also conducted brief observations in all 13 stores licensed to sell alcohol on and close to the reservation lands of the nine tribes. Underage youth may obtain alcoholic beverages at stores either directly through illegal sales to minors or indirectly through social sources. Stores are also environments within which alcoholic beverages and heavy drinking may become normalized for youth. Limitations and implications for convenience store-based prevention research on alcohol retail environment for youth in rural populations areas are discussed.

Chronic intermittent ethanol exposure during adolescence: effects on social behavior and ethanol sensitivity in adulthood

This study assessed long-lasting consequences of repeated ethanol exposure during two different periods of adolescence on 1) baseline levels of social investigation, play fighting, and social preference and 2) sensitivity to the social consequences of acute ethanol challenge. Adult male and female Sprague-Dawley rats were tested 25 days after repeated exposure to ethanol (3.5 g/kg intragastrically [i.g.], every other day for a total of 11 exposures) in a modified social interaction test. Early-mid adolescent intermittent exposure (e-AIE) occurred between postnatal days (P) 25 and 45, whereas late adolescent intermittent exposure (l-AIE) was conducted between P45 and P65. Significant decreases in social investigation and social preference were evident in adult male rats, but not their female counterparts following e-AIE, whereas neither males nor females demonstrated these alterations following l-AIE. In contrast, both e-AIE and l-AIE produced alterations in sensitivity to acute ethanol challenge in males tested 25 days after adolescent exposure. Ethanol-induced facilitation of social investigation and play fighting, reminiscent of that normally seen during adolescence, was evident in adult males after e-AIE, whereas control males showed an age-typical inhibition of social behavior. Males after l-AIE were found to be insensitive to the socially suppressing effects of acute ethanol challenge, suggesting the development of chronic tolerance in these animals. In contrast, females showed little evidence for alterations in sensitivity to acute ethanol challenge following either early or late AIE. The results of the present study demonstrate a particular vulnerability of young adolescent males to long-lasting detrimental effects of repeated ethanol. Retention of adolescent-typical sensitivity to the socially facilitating effects of ethanol could potentially make ethanol especially appealing to these males, therefore promoting relatively high levels of ethanol intake later in life.

Associations between a history of binge drinking during adolescence and self-reported responses to alcohol in young adult Native and Mexican Americans

BACKGROUND

Binge drinking during adolescence is common and may predict increased drinking in young adulthood and enhanced risk of alcohol dependence. Variation in level of response to the hedonic and adverse effects of alcohol is in part an inherited factor that may also influence its use, abuse, and dependence. This study investigated, in young adults, whether an association could be demonstrated between variation in self-reported responses to alcohol and a history of binge drinking during adolescence.

METHODS

Young adult (18 to 30 years, n = 790) Native Americans and Mexican Americans were recruited from the community and completed a structured diagnostic interview. Response to alcohol was indexed using the expectation version of the Subjective High Assessment Scale (SHAS-E). An adolescent history of regular binge drinking was defined as drinking 5 or more drinks for boys and 4 or more drinks for girls per drinking occasion at least once a month during their highest drinking period prior to the age of 18.

RESULTS

An adolescent history of regular binge drinking was found to be associated with a lower level of self-reported responses to the negative aspects of alcohol intoxication (feeling terrible) as well as to the overall level of intoxication, but not to the positive impressions of intoxication (feeling great) on the SHAS-E. A history of regular adolescent binge drinking was also correlated with less feelings of the "terrible" and "total" effects of alcohol, as indexed by the SHAS-E, in a linear regression model that included several diagnostic and demographic variables such as a history of conduct disorder and current levels of drinking.

CONCLUSIONS

These data suggest that a history of adolescent binge drinking is associated with a reduction in the self-reported level of intoxication in young adulthood, a factor that could theoretically lead to increased risk of alcohol dependence.

Event-related potential responses to the acute and chronic effects of alcohol in adolescent and adult Wistar rats

BACKGROUND

This study explored the hypothesis that adolescent ethanol (EtOH) exposure may cause long-lasting changes in EtOH sensitivity by exploring the age-related effects of acute alcohol on intoxication and on event-related potential (ERP) responses to acoustic stimuli in EtOH-naïve adolescent and adult male Wistar rats and in adult rats that were exposed to chronic EtOH/control conditions during adolescence.

METHODS

EtOH-naïve adolescent (postnatal day 32 [PD32]) and adult male rats (PD99) were included in the first study. In a second study, rats were exposed to 5 weeks of EtOH vapor (blood EtOH concentrations at 175 mg%) or air from PD24 to 59 and allowed to mature until PD90. In both studies, rats were implanted with cortical recording electrodes, and the effects of acute EtOH (0.0, 1.5, and 3.0 g/kg) on behavioral and ERP responses were assessed.

RESULTS

Adolescents were found to have higher amplitude and longer latency P3a and P3b components at baseline as compared to adult rats, and EtOH was found to produce a robust dose-dependent increase in the latency of the P3a and P3b components of the auditory ERP recorded in cortical sites in both adolescents and adults. However, EtOH produced significantly larger delays in P3a and P3b latencies in adults as compared to adolescents. Acute EtOH administration was also found to produce a robust dose-dependent increase in the latency of the P3a and P3b components in adult animals exposed to EtOH vapor as adolescents and air exposed controls; however, larger acute EtOH-induced increases in P3a and P3b latencies were seen in controls as compared to adolescent vapor exposed rats.

CONCLUSIONS

Adolescent rats have a less intense P3 latency response to acute EtOH administration when compared to adult rats. Exposure to chronic EtOH during adolescence can cause "retention" of the adolescent phenotype of reduced P3 latency sensitivity to EtOH.

Usefulness of a survey on underage drinking in a rural American Indian community health clinic

This study examined the usefulness of a survey on underage drinking in a rural American Indian community health clinic. One hundred ninety-seven youth (90 male, 107 female; age range 8-20 years) were recruited from clinic waiting rooms and through community outreach. The study revealed that the usefulness of the survey was twofold: Survey results could be used by clinic staff to screen for underage drinking and associated problems in youth served by the clinic, and the process of organizing, evaluating, and implementing the survey results accomplished several important goals of community-based participatory research.

Developmental differences in EEG and sleep responses to acute ethanol administration and its withdrawal (hangover) in adolescent and adult Wistar rats

Age-related differences in sensitivity to the acute effects of alcohol may play an important role in the increased risk for the development of alcoholism seen in teens that begin drinking at an early age. The present study evaluated the acute and protracted (hangover) effects of ethanol in adolescent (P33-P40) and adult (P100-P107) Wistar rats, using the cortical electroencephalogram (EEG). Six minutes of EEG was recorded during waking, 15 min after administration of 0, 1.5, or 3.0 g/kg ethanol, and for 3 h at 20 h post ethanol, during the rats' next sleep cycle. Significantly higher overall frontal and parietal cortical power was seen in a wide range of EEG frequencies in adolescent rats as compared to adult rats in their waking EEG. Acute administration of ethanol did not produce differences between adolescents and adults on behavioral measures of acute intoxication. However, it did produce a significantly less intense acute EEG response to ethanol in the theta frequencies in parietal cortex in the adolescents as compared to the adults. At 20 h following acute ethanol administration, during the rats' next sleep cycle, a decrease in slow-wave frequencies (1-4 Hz) was seen and the adolescent rats were found to display more reduction in the slow-wave frequencies than the adults did. The present study found that adolescent rats, as compared to adults, demonstrate low sensitivity to acute ethanol administration in the theta frequencies and more susceptibility to disruption of slow-wave sleep during hangover. These studies may lend support to the idea that these traits may contribute to increased risk for alcohol use disorders seen in adults who begin drinking in their early teenage years.

Measuring historical trauma in an American Indian community sample: contributions of substance dependence, affective disorder, conduct disorder and PTSD

BACKGROUND

The American Indian experience of historical trauma is thought of as both a source of intergenerational trauma responses as well as a potential causative factor for long-term distress and substance abuse among communities. The aims of the present study were to evaluate the extent to which the frequency of thoughts of historical loss and associated symptoms are influenced by: current traumatic events, post traumatic stress disorder (PTSD), cultural identification, percent Native American Heritage, substance dependence, affective/anxiety disorders, and conduct disorder/antisocial personality disorder (ASPD).

METHODS

Participants were American Indians recruited from reservations that were assessed with the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), The Historical Loss Scale and The Historical Loss Associated Symptoms Scale (to quantify frequency of thoughts and symptoms of historical loss) the Stressful-Life-Events Scale (to assess experiences of trauma) and the Orthogonal Cultural Identification Scale (OCIS).

RESULTS

Three hundred and six (306) American Indian adults participated in the study. Over half of them indicated that they thought about historical losses at least occasionally, and that it caused them distress. Logistic regression revealed that significant increases in how often a person thought about historical losses were associated with: not being married, high degrees of Native Heritage, and high cultural identification. Additionally, anxiety/affective disorders and substance dependence were correlated with historical loss associated symptoms.

CONCLUSIONS

In this American Indian community, thoughts about historical losses and their associated symptomatology are common and the presence of these thoughts are associated with Native American Heritage, cultural identification, and substance dependence.

Evidence for a genetic component for substance dependence in Native Americans

OBJECTIVE

Although tribes differ with regard to the use of alcohol and drugs, substance dependence is one of the primary sources of health problems facing Native Americans. General population studies have demonstrated that substance dependence has a substantially heritable component (approximately 50% of the risk resulting from genetic influences); however, fewer studies have investigated the role of genetics in the risk for substance dependence in Native Americans.

METHOD

The authors present a literature review of the evidence for a genetic component in the etiology of substance dependence in Native Americans, including studies of heritability, linkage analyses, and candidate genes.

RESULTS

Evidence for the heritability of alcohol and drug dependence was found. Linkage analyses revealed that genes influencing risk for substance dependence and related phenotypes, such as body mass index (BMI), drug tolerance, EEG patterns, and externalizing traits, reside on several chromosome regions identified in other population samples. Overlap in the gene locations for substance dependence and BMI suggests that a common genetic substrate may exist for disorders of consumption. Studies of the genes that code for alcohol-metabolizing enzymes have not revealed any risk variants specific to Native American populations, although most Native Americans lack protective variants seen in other populations. Other candidate genes associated with substance dependence phenotypes in Native Americans include OPRM1, CRN1, COMT, GABRA2, MAOA, and HTR3-B.

CONCLUSIONS

Substance dependence has a substantial genetic component in Native Americans, similar in magnitude to that reported for other populations. The high rates of substance dependence seen in some tribes is likely a combination of a lack of genetic protective factors (metabolizing enzyme variants) combined with genetically mediated risk factors (externalizing traits, consumption drive, and drug sensitivity or tolerance) that combine with key environmental factors (trauma exposure, early age at onset of use, and environmental hardship) to produce an elevated risk for the disorder.

Lifetime history of traumatic events in an American Indian community sample: heritability and relation to substance dependence, affective disorder, conduct disorder and PTSD

American Indians appear to experience a higher rate of traumatic events than what has been reported in general population surveys. American Indians also suffer higher alcohol related death rates than any other ethnic group in the U.S. population. Therefore efforts to delineate factors which may uniquely contribute to increased likelihood of trauma, post traumatic stress disorder (PTSD), and substance use disorders (SUD) over the lifetime in American Indians are important because of the high burden of morbidity and mortality that they pose to American Indian communities. Participants were American Indians recruited from reservations that were assessed with the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), family history assessment and the stressful-life-events scale. Of the 309 participants, equivalent numbers of men and women (94%) reported experiencing traumas; however, a larger proportion of women received a PTSD diagnosis (38%) than men (29%). Having experienced multiple trauma and sexual abuse were most highly associated with PTSD. Having experienced assaultive trauma and having PTSD symptoms were both found to be moderately heritable (30-50%). Logistic regression revealed that having an anxiety and/or affective disorder and having a substance dependent diagnosis, but not having antisocial personality disorder/conduct disorder, were significantly correlated with having a diagnosis of PTSD. These studies suggest that trauma is highly prevalent in this American Indian community, it is heritable, is associated with PTSD, affective/anxiety disorders and substance dependence. Additionally, trauma, PTSD and substance dependence appear to all co-emerge in early adulthood in this high-risk population.

Implementing a reward and reminder underage drinking prevention program in convenience stores near Southern California American Indian reservations

BACKGROUND

Underage drinking is associated with a number of social and public health consequences. Preventing access to alcohol is one approach to reducing underage drinking.

OBJECTIVES

This study assesses the efficacy of a culturally tailored "reward and reminder" program aimed at reducing convenience store alcohol sales to youth living on or near nine American Indian reservations.

METHODS

First, tribal council proclamations were sought to support underage drinking prevention, including reward and reminder efforts. Then, decoys (volunteers over 21 years of age but judged to look younger) attempted to purchase alcohol without identification. Clerks who asked for identification were given "rewards" (gift cards and congratulatory letters), whereas clerks who did not were given "reminders" of the law regarding sales to minors. Following an initial baseline of 12 purchase attempts, three repeated reward and reminder visits were made to 13 convenience stores selling alcohol within 10 miles of the reservations (n = 51 total attempts).

RESULTS

Five of nine tribal councils passed resolutions in support of the program. The baseline sales rate without requesting ID was 33%. Similarly, 38% of stores in the first reward and reminder visit round failed to request identification. However, in the following two reward and reminder rounds, 0% of the stores failed to request identification.

CONCLUSIONS

These results indicate that environmental community-level underage drinking prevention strategies to reduce alcohol sales near rural reservations are feasible and can be effective.

SCIENTIFIC SIGNIFICANCE

Environmental prevention strategies within reservation communities support integrated supply and demand reduction models for reducing underage drinking.

Similar ethanol drinking in adolescent and adult C57BL/6J mice after chronic ethanol exposure and withdrawal

BACKGROUND

Increasing evidence shows that excessive alcohol consumption during adolescence increases vulnerability to alcohol use disorders in adulthood. The aim of this study was to examine differences between adolescent and adult C57BL/6J mice in drinking behavior and blood ethanol (EtOH) concentrations (BECs) after chronic EtOH exposure and withdrawal.

METHODS

Male adolescent (PND = 28 to 30) and adult (PND = 70) C57BL/6J mice were allowed to consume EtOH in a 2-bottle choice paradigm (15% EtOH vs. water) for 3 weeks (Baseline drinking, Test 1, and Test 2), which were interspersed with 2 cycles (Cycles I and II) of chronic EtOH vapor or air inhalation (16 hours) and withdrawal (8 hours). BECs were determined during both cycles.

RESULTS

Chronic EtOH exposure led to increased EtOH intake during Test 1 and Test 2 in both adolescent and adult mice compared with air-exposed controls, and no differences between age groups were observed. During Cycle I adult mice showed higher BECs compared with adolescents. During Cycle II, BECs were lower in adult mice as compared to Cycle I, and BECs in adolescent mice did not change between the 2 cycles.

CONCLUSIONS

Chronic EtOH exposure followed by withdrawal periods increases EtOH consumption similarly in both adolescent and adult mice, despite differences in BECs.

Ethanol pre-exposure during adolescence or adulthood increases ethanol intake but ethanol-induced conditioned place preference is enhanced only when pre-exposure occurs in adolescence

Behavioral sensitization has been suggested to contribute to uncontrolled alcohol consumption. The aim of this study was to investigate the effects of repeated ethanol administration in adolescent and adult mice on subsequent ethanol consumption and conditioned place preference (CPP). Mice were administered ethanol for 15 consecutive days. This ethanol regimen induced behavioral sensitization to a lesser degree in adolescents than in adults. Following ethanol treatment, mice were subjected to CPP procedure, or given a free choice between water and ethanol solutions. While ethanol-pretreated adult mice did not display a robust ethanol-induced CPP, ethanol induced a significant CPP in mice pretreated with ethanol during adolescence. Ethanol pretreated mice, regardless of age, showed higher ethanol intake to saline-treated mice. The present findings suggest that ethanol-induced neuroadaptations underlying behavioral sensitization may activate mechanisms responsible for enhanced ethanol intake, and also reveals that ethanol pre-exposure during adolescence increases ethanol reward as measured by CPP.

Effects of adolescent onset voluntary drinking followed by ethanol vapor exposure on subsequent ethanol consumption during protracted withdrawal in adult Wistar rats

Epidemiological studies have demonstrated that heavy drinking and alcohol abuse and dependence peak during the transition between late adolescence and early adulthood. The objective of the present study was to determine whether a model of early onset adolescent ethanol drinking exposure that is followed by an ethanol vapor regimen during late adolescence and young adulthood leads to an increase in drinking in adulthood. In this model, initiation of voluntary ethanol drinking in adolescence, using a sweetened solution, was followed by an 8-wk intermittent ethanol vapor regimen in Wistar rats. A limited-access two-bottle choice paradigm was then used to measure intake of a 10% (w/v) ethanol solution. No differences in water intake (g/kg), total fluid intake (ml/kg) and body weight (g) were observed between air-exposed and ethanol-vapor exposed groups during the pre-vapor and post-vapor phases. The 8 weeks of ethanol vapor exposure was found to produce only a modest, but statistically significant, elevation of ethanol intake during the protracted withdrawal period, compared to air-exposed rats. A significant increase in ethanol preference ratio was also observed in ethanol-vapor exposed rats during the sucrose-fading phase, but not during the protracted withdrawal period. The findings from the present study suggest that in addition to alcohol exposure, environmental variables that impact appetitive as well as consumptive behaviors may be important in developing robust drinking effects that model, in animals, the increased risk for alcohol dependence seen in some human adolescents who begin drinking at an early age.