The human adolescent brain and alcohol use disorders

Nutrition in school-age children: a rationale for revisiting priorities

Middle childhood and early adolescence have received disproportionately low levels of scientific attention relative to other life stages, especially as related to nutrition and health. This is partly due to the justified emphasis on the first 1000 days of life, and the idea that early deficits and consequences may not be fully reversible. In addition, these stages of life may superficially appear less "eventful" than infancy or late adolescence. Finally, there has been historical ambiguity and inconsistency in terminology, depending on whether viewing "childhood" through physiologic, social, legal, or other lenses. Nevertheless, this age bracket, which encompasses most of the primary education and basic schooling years for most individuals, is marked by significant changes, inflection points, and sexually driven divergence in somatic and brain growth and development trajectories. These constitute transformative changes, and thus middle childhood and early adolescence represents a major and last opportunity to influence long-term health and productivity. This review highlights the specificities of growth and development in school age, with a focus on middle childhood and early adolescence (5 years-15 years of age, for the purposes of this review), the role of nutrition, the short- and long-term consequences of inadequate nutrition, and the current global status of nutrition in this age group. Adequate attention and emphasis on nutrition in the school-age years is critical: (a) for maintaining an adequate course of somatic and cognitive development, (b) for taking advantage of this last major opportunity to correct deficits of undernutrition and "catch-up" to normal life course development, and (c) for addressing the nutritional inadequacies and mitigating the longer-term consequences of overnutrition. This review summarizes and provides a rationale for prioritizing nutrition in school-age children, and for the need to revisit priorities and focus on this part of the life cycle to maximize individuals' potential and their contribution to society.

Neuroscience Outside the Box: From the Laboratory to Discussing Drug Abuse at Schools

One of the effects of the current COVID-19 pandemic is that low-income countries were pushed further into extreme poverty, exacerbating social inequalities and increasing susceptibility to drug use/abuse in people of all ages. The risks of drug abuse may not be fully understood by all members of society, partly because of the taboo nature of the subject, and partly because of the considerable gap between scientific production/understanding and communication of such knowledge to the public at large. Drug use is a major challenge to social development and a leading cause of school dropout rates worldwide. Some public policies adopted in several countries in recent decades failed to prevent drug use, especially because they focused on imposing combative or coercive measures, investing little or nothing in education and prevention. Here we highlight the role of neuroscience education as a valid approach in drug use education and prevention. We propose building a bridge between schools and scientists by promoting information, student engagement and honest dialogue, and show evidence that public policy regulators should be persuaded to support such science-based education programs in their efforts to effect important positive changes in society.

Alcohol Induced Brain and Liver Damage: Advantages of a Porcine Alcohol Use Disorder Model

Alcohol is one of the most commonly abused intoxicants with 1 in 6 adults at risk for alcohol use disorder (AUD) in the United States. As such, animal models have been extensively investigated with rodent AUD models being the most widely studied. However, inherent anatomical and physiological differences between rodents and humans pose a number of limitations in studying the complex nature of human AUD. For example, rodents differ from humans in that rodents metabolize alcohol rapidly and do not innately demonstrate voluntary alcohol consumption. Comparatively, pigs exhibit similar patterns observed in human AUD including voluntary alcohol consumption and intoxication behaviors, which are instrumental in establishing a more representative AUD model that could in turn delineate the risk factors involved in the development of this disorder. Pigs and humans also share anatomical similarities in the two major target organs of alcohol- the brain and liver. Pigs possess gyrencephalic brains with comparable cerebral white matter volumes to humans, thus enabling more representative evaluations of susceptibility and neural tissue damage in response to AUD. Furthermore, similarities in the liver result in a comparable rate of alcohol elimination as humans, thus enabling a more accurate extrapolation of dosage and intoxication level to humans. A porcine model of AUD possesses great translational potential that can significantly advance our current understanding of the complex development and continuance of AUD in humans.

Alterations in White Matter Microstructure and Connectivity in Young Adults with Alcohol Use Disorder

BACKGROUND

Magnetic resonance imaging (MRI) studies have shown differences in volume and structure in the brains of individuals with alcohol use disorder (AUD). Most research has focused on neuropathological effects of alcohol that appear after years of chronic alcohol misuse. However, few studies have investigated white matter (WM) microstructure and diffusion MRI-based (DWI) connectivity during early stages of AUD. Therefore, the goal of this work was to investigate WM integrity and structural connectivity in emerging adulthood AUD subjects using both conventional DWI metrics and a novel connectomics approach.

METHODS

Twenty-two AUD and 18 controls (CON) underwent anatomic and diffusion MRI. Outcome measures were scalar diffusion metrics and structural network connectomes. Tract-Based Spatial Statistics was used to investigate group differences in diffusion measures. Structural connectomes were used as input into a community structure procedure to obtain a coclassification index matrix (an indicator of community association strength) for each subject. Differences in coclassification and structural connectivity (indexed by streamline density) were assessed via the Network Based Statistics Toolbox.

RESULTS

AUD had higher fractional anisotropy (FA) values throughout the major WM tracts, but also had lower FA values in WM tracts in the cerebellum and right insula (p_TFCE  < 0.05). Mean diffusivity was generally lower in the AUD group (p_TFCE  < 0.05). AUD had lower coclassification of nodes between ventral attention and default mode networks and higher coclassification between nodes of visual, default mode, and somatomotor networks. Additionally, AUD had higher fiber density between an adjacent pair of nodes within the default mode network.

CONCLUSIONS

Our results indicate that emerging adulthood AUD subjects may have differential patterns of FA and distinct differences in structural connectomes compared with CON. These data suggest that such alterations in microstructure and structural connectivity may uniquely characterize early stages of AUD and/or a predisposition for development of AUD.

Neurobiological Effects of Binge Drinking Help in Its Detection and Differential Diagnosis from Alcohol Dependence

The prevalence of binge drinking in the general population is 3-4 times higher than that of alcohol dependence. Neuroimaging studies show that binge drinking in adolescence impairs brain development and white matter integrity. Regions with reduced functional activity include the limbic system, ventral diencephalon, frontal lobe, and middle and inferior temporal lobes, whereas the right superior frontal and parietal lobes are typically hyperactivated. The observed activation of the frontoparietal areas might reflect the alternative memory system operating, whereas the reduced occipito-hippocampal response is associated with impaired visual and linguistic processing/learning. Some other findings from literature research include a decrease of N-acetylaspartate (NAA) in the frontal lobe and its increase in the parietal lobes, as well as the reduced components of event-related potentials, reflecting deficit in attention, working memory, inhibition, and executive functioning. Animal studies show that even a single day of binge drinking results in a neurodegeneration and reactive gliosis in the limbic cortex as well as in gene expression dysregulation and histone acetylation. Another biological evidence on binge drinking effect include inflammatory response, oxidative stress, formation of toxic ceramides, activation of caspase 3, and secretion of corticoliberin. Some of the binge drinking-induced cognitive abnormalities can be reversible after three weeks of abstinence. Although binge drinkers have a similar pattern of neuropsychological deficits with chronic alcohol consumers (mainly memory deficits), binge drinkers have prominent impairment of inhibitory control, which may be a marker of binge pattern of alcohol drinking. The optimal therapeutic strategies should target the inhibitory control processes to facilitate discontinuation of alcohol consumption and to block its possible progression to the alcohol dependence syndrome.

Drinker Identity: Key Risk Factor for Adolescent Alcohol Use

BACKGROUND

Adolescent alcohol use continues to be a critical public health problem with both short- and long-term negative health consequences. Defining oneself in terms of alcohol, a drinking-related identity, has been shown to predict high levels of alcohol use. Because adolescence is the developmental period during which identity development is most salient, preventing the development of the drinker identity and early identification of youth who have a developing drinker identity may be important for prevention and early intervention.

METHODS

We review the theory- and evidence-based literature about identity development and the effects of a drinker identity on alcohol use behaviors in adolescents, discuss potential determinants of the drinker identity, and discuss future implications for practice and research.

RESULTS

There is some evidence that the drinker identity forms in early adolescence and becomes more well-developed during adolescence. The drinker identity predicts alcohol use behaviors both concurrently and over time in adolescence and young adulthood. There is also some evidence that early exposure to alcohol may contribute to formation of the drinker identity.

CONCLUSIONS

Identity-based approaches may be promising strategies to identify adolescents who are at risk for alcohol use and to intervene with early prevention or treatment within the school setting.

Homer2 within the central nucleus of the amygdala modulates withdrawal-induced anxiety in a mouse model of binge-drinking

A history of binge-drinking decreases protein expression of the glutamate-related scaffolding protein Homer2 within the central nucleus of the amygdala (CEA), coinciding with behavioral signs of negative affect. To assess the functional relevance of this protein change for withdrawal-induced hyper-anxiety, adult (PND 56) and adolescent (PND 28) male C57BL/6J mice were administered an intra-CEA infusion of an adeno-associated viral vector (AAV) carrying either cDNA to express Homer2 (H2-cDNA) or GFP as control. Mice underwent 14 days of binge-drinking under multi-bottle, limited-access conditions and were assayed for behavioral signs of negative affect during withdrawal using the light-dark box, marble burying, and forced swim tests (FST). Following behavioral testing, all animals experienced 5 days of drinking to evaluate the effects of prior alcohol experience and Homer2 manipulation on subsequent alcohol consumption. During protracted (4 weeks) withdrawal, adolescent alcohol-experienced GFP controls showed increased signs of negative affect across all 3 assays, compared to water-drinking GFP animals, and also showed elevated alcohol consumption during the subsequent drinking period. Homer2-cDNA infusion in adolescent-onset alcohol-drinking animals was anxiolytic and reduced subsequent alcohol consumption. Conversely, Homer2-cDNA was anxiogenic and increased drinking in water-drinking adolescents. Unfortunately, the data from adult-onset alcohol-drinking animals were confounded by low alcohol consumption and negligible behavioral signs of anxiety. Nevertheless, the present results provide novel cause-effect evidence supporting a role for CEA Homer2 in the regulation of both basal anxiety and the time-dependent intensification of negative affective states in individuals with a history of binge-drinking during adolescence.

Negative Affect and Excessive Alcohol Intake Incubate during Protracted Withdrawal from Binge-Drinking in Adolescent, But Not Adult, Mice

Binge-drinking is common in underage alcohol users, yet we know little regarding the biopsychological impact of binge-drinking during early periods of development. Prior work indicated that adolescent male C57BL6/J mice with a 2-week history of binge-drinking (PND28-41) are resilient to the anxiogenic effects of early alcohol withdrawal. Herein, we employed a comparable Drinking-in-the-Dark model to determine how a prior history of binge-drinking during adolescence (EtOH^adolescents) influences emotionality (assayed with the light-dark box, marble burying test, and the forced swim test) and the propensity to consume alcohol in later life, compared to animals without prior drinking experience. For additional comparison, adult mice (EtOH^adults) with comparable drinking history (PND56-69) were subdivided into groups tested for anxiety/drinking either on PND70 (24 h withdrawal) or PND98 (28 days withdrawal). Tissue from the nucleus accumbens shell (AcbSh) and central nucleus of the amygdala (CeA) was examined by immunoblotting for changes in the expression of glutamate-related proteins. EtOH^adults exhibited some signs of hyperanxiety during early withdrawal (PND70), but not during protracted withdrawal (PND98). In contrast, EtOH^adolescents exhibited robust signs of anxiety-l and depressive-like behaviors when tested as adults on PND70. While all alcohol-experienced animals subsequently consumed more alcohol than mice drinking for the first time, alcohol intake was greatest in EtOH^adolescents. Independent of drinking age, the manifestation of withdrawal-induced hyperanxiety was accompanied by reduced Homer2b expression within the CeA and increased Group1 mGlu receptor expression within the AcbSh. The present data provide novel evidence that binge-drinking during adolescence produces a state characterized by profound negative affect and excessive alcohol consumption that incubates with the passage of time in withdrawal. These data extend our prior studies on the effects of subchronic binge-drinking during adulthood by demonstrating that the increase in alcoholism-related behaviors and glutamate-related proteins observed in early withdrawal dissipate with the passage of time. Our results to date highlight a critical interaction between the age of binge-drinking onset and the duration of alcohol withdrawal in glutamate-related neuroplasticity within the extended amygdala of relevance to the etiology of psychopathology, including pathological drinking, in later life.

Neuroscience-Inspired, Behavioral Change Program for University Students

It is clear that environmental influences impact the structure and function of the human brain, and thus, thoughts, actions, and behaviors. These in turn influence whether an individual engages in high-risk (drugs, alcohol, violence) or health-promoting (exercise, meditation, music) activities. The developmental mismatch between cortical and subcortical maturation of the transitional age brain places college students at risk for negative outcomes. This article argues that the prescription of incentive-based behavioral change and brain-building activities simply make good scientific, programmatic, and financial sense for colleges and universities. The authors present University of Vermont Wellness Environment as an example.

Childhood adversity is linked to differential brain volumes in adolescents with alcohol use disorder: a voxel-based morphometry study

Previous neuroimaging studies link both alcohol use disorder (AUD) and early adversity to neurobiological differences in the adult brain. However, the association between AUD and childhood adversity and effects on the developing adolescent brain are less clear, due in part to the confound of psychiatric comorbidity. Here we examine early life adversity and its association with brain volume in a unique sample of 116 South African adolescents (aged 12-16) with AUD but without psychiatric comorbidity. Participants were 58 adolescents with DSM-IV alcohol dependence and with no other psychiatric comorbidities, and 58 age-, gender- and protocol-matched light/non-drinking controls (HC). Assessments included the Childhood Trauma Questionnaire (CTQ). MR images were acquired on a 3T Siemens Magnetom Allegra scanner. Volumes of global and regional structures were estimated using SPM8 Voxel Based Morphometry (VBM), with analysis of covariance (ANCOVA) and regression analyses. In whole brain ANCOVA analyses, a main effect of group when examining the AUD effect after covarying out CTQ was observed on brain volume in bilateral superior temporal gyrus. Subsequent regression analyses to examine how childhood trauma scores are linked to brain volumes in the total cohort revealed a negative correlation in the left hippocampus and right precentral gyrus. Furthermore, bilateral (but most significantly left) hippocampal volume was negatively associated with sub-scores on the CTQ in the total cohort. These findings support our view that some alterations found in brain volumes in studies of adolescent AUD may reflect the impact of confounding factors such as psychiatric comorbidity rather than the effects of alcohol per se. In particular, early life adversity may influence the developing adolescent brain in specific brain regions, such as the hippocampus.

GABAergic contributions to alcohol responsivity during adolescence: insights from preclinical and clinical studies

There is a considerable body of literature demonstrating that adolescence is a unique age period, which includes rapid and dramatic maturation of behavioral, cognitive, hormonal and neurobiological systems. Most notably, adolescence is also a period of unique responsiveness to alcohol effects, with both hyposensitivity and hypersensitivity observed to the various effects of alcohol. Multiple neurotransmitter systems are undergoing fine-tuning during this critical period of brain development, including those that contribute to the rewarding effects of drugs of abuse. The role of developmental maturation of the γ-amino-butyric acid (GABA) system, however, has received less attention in contributing to age-specific alcohol sensitivities. This review integrates GABA findings from human magnetic resonance spectroscopy studies as they may translate to understanding adolescent-specific responsiveness to alcohol effects. Better understanding of the vulnerability of the GABA system both during adolescent development, and in psychiatric conditions that include alcohol dependence, could point to a putative mechanism, boosting brain GABA, that may have increased effectiveness for treating alcohol use disorders.

Adolescent heavy episodic drinking: neurocognitive functioning during early abstinence

The present study investigated the rate and pattern of neuropsychological recovery in heavy episodic drinking teens during the initial days to weeks of abstinence from alcohol. Adolescents (ages, 16-18 years) with histories of heavy episodic drinking (HED; N = 39) and socio-demographically similar control teens (CON; N = 26) were recruited from San Diego area schools. HED and CON were comparable on 5th grade standardized math and language arts test performance to ensure similar functioning before onset of substance use. Participants were administered three neuropsychological test batteries with 2-week intervals during a 4-week monitored abstinence period. HED teens performed worse overall than CON on tests of prospective memory (p = .005), cognitive switching (p = .039), inhibition task accuracy (p = .001), verbal memory (p's < .045), visuospatial construction (p's < .043), and language and achievement (p's < .008). The statistically significant group × time interaction for block design demonstrated normalization within the 4 weeks of abstinence for the HED (p = .009). This study identified cognitive performance deficits associated with heavy episodic drinking in adolescence during early abstinence and with sustained 4-week abstention. These findings suggest alcohol-related influences on several underlying brain systems that may predate the onset of alcohol abuse or dependence or take longer than 4 weeks to recover.

fMRI response during figural memory task performance in college drinkers

RATIONALE

Eighteen- to twenty-five-year-olds show the highest rates of alcohol use disorders (AUD) and heavy drinking, which may have critical neurocognitive implications. Regions subserving memory may be particularly susceptible to alcohol-related impairments.

OBJECTIVE

We used blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to examine the neural correlates of visual encoding and recognition among heavy-drinking college students. We predicted that heavy drinkers would show worse memory performance, increased frontal/parietal activation, and decreased hippocampal response during encoding.

METHODS

Participants were 23 heavy drinkers and 33 demographically matched light drinkers, aged 18-20, characterized using quantity/frequency of drinking and AUD diagnosis. Participants performed a figural encoding and recognition task during fMRI. BOLD response during encoding was modeled based on whether each stimulus was subsequently recognized or forgotten (i.e., correct vs. incorrect encoding).

RESULTS

There were no group differences in behavioral performance. Compared to light drinkers, heavy drinkers showed (1) greater BOLD response during correct encoding in the right hippocampus/medial temporal, right dorsolateral prefrontal, left inferior frontal, and bilateral posterior parietal cortices; (2) less left inferior frontal activation and greater bilateral precuneus deactivation during incorrect encoding; and (3) less bilateral insula response during correct recognition (clusters >10,233 μl, p < 0.05 whole brain).

CONCLUSIONS

This is the first investigation of the neural substrates of figural memory among heavy-drinking older adolescents. Heavy drinkers demonstrated compensatory hyperactivation of memory-related areas during correct encoding, greater deactivation of default mode regions during incorrect encoding, and reduced recognition-related response. Results could suggest use of different encoding and recognition strategies among heavy drinkers.

A randomized controlled trial of a group motivational interviewing intervention for adolescents with a first time alcohol or drug offense

Group motivational interviewing (MI) interventions that target youth at-risk for alcohol and other drug (AOD) use may prevent future negative consequences. Youth in a teen court setting [n=193; 67% male, 45% Hispanic; mean age 16.6 (SD=1.05)] were randomized to receive either a group MI intervention, Free Talk, or usual care (UC). We examined client acceptance, and intervention feasibility and conducted a preliminary outcome evaluation. Free Talk teens reported higher quality and satisfaction ratings, and MI integrity scores were higher for Free Talk groups. AOD use and delinquency decreased for both groups at 3 months, and 12-month recidivism rates were lower but not significantly different for the Free Talk group compared to UC. Results contribute to emerging literature on MI in a group setting. A longer term follow-up is warranted.

Advances in the science of adolescent drug involvement: implications for assessment and diagnosis - experience from the United States

PURPOSE OF REVIEW

Adolescence is a developmental period characterized by relatively high rates of substance use and substance use disorders. Precise assessment and classification of adolescent drug use behaviors are essential in gaining an accurate understanding of the nature and extent of adolescent drug use, and possible intervention or treatment needs. There has been a select group of recently published research reports and manuscripts that address critical and emerging issues pertaining to the classification and assessment of alcohol and other drug use behaviors among adolescents. An overview of these publications is provided and their clinical relevance is discussed.

RECENT FINDINGS

The paper will focus on recent research, most from the United States, that addresses four main issues. One is the application of the new DSM-5 criteria to adolescents, including the advantages and disadvantages of the new criteria for substance use disorders. The second issue pertains to advances in instrumentation that provide new tools for researchers and clinicians in assessing substance use in adolescents. A significant public health issue is addressed as the third theme in the paper - screening for alcohol abuse in college settings. Finally, the paper reviews how the emerging science of brain development can inform the assessment process.

SUMMARY

Recent advances in the adolescent drug abuse assessment field continue to inform clinical service and research. As a whole, these advances have strengthened the field, but continued research is needed to further refine assessment practices and standards and to better understand how to define a substance use disorder in youth.

Adolescent neurobehavioral characteristics, alcohol sensitivities, and intake: Setting the stage for alcohol use disorders?

The transition to adolescence is characterized by rapid biological transformations that include not only the hormonal and physiological changes of puberty but also dramatic changes in the brain as well. Similar neural and physiological changes are associated with the transition from immaturity to maturity across a variety of mammalian species, along with a variety of common adolescent-typical behavioral characteristics. Among the neural systems undergoing alterations during adolescence are those that modulate sensitivity to a variety of alcohol effects, potentially increasing the propensity for relatively high levels of adolescent alcohol use, which in turn may set the stage for later alcohol use disorders. This article reviews research on adolescent alcohol sensitivities and suggests possible implications of these findings for the frequent initiation and relatively high levels of alcohol intake seen at this age.

Early adolescent executive functioning, intrauterine exposures and own drug use

Individual differences in adolescents' executive functioning are often attributed either to intrauterine substance exposure or to adolescents' own substance use, but both predictors typically have not been evaluated simultaneously in the same study. This prospective study evaluated whether intrauterine drug exposures, the adolescents' own substance use, and/or their potential interactions are related to poorer executive functioning after controlling for important contextual variables. Analyses were based on data collected on a sample of 137 predominantly African-American/African Caribbean adolescents from low-income urban backgrounds who were followed since their term birth. Intrauterine substance exposures (cocaine, marijuana, alcohol, and cigarettes) and adolescents' substance use were documented using a combination of biological assays and maternal and adolescent self-report. At 12-14 years of age, examiners masked to intrauterine exposures and current substance use assessed the adolescents using the Delis-Kaplan Executive Function System (D-KEFS), an age-referenced instrument evaluating multiple dimensions of executive functioning (EF). Results of covariate-controlled analyses in this study suggest that when intrauterine substance exposures and young adolescents' substance use variables were in the same analysis models, subtle differences in specific EF outcomes were identifiable in this non-referred sample. While further study with larger samples is indicated, these findings suggest that 1) research on adolescent substance use and intrauterine exposure research should evaluate both predictors simultaneously, 2) subtle neurocognitive effects associated with specific intrauterine drug exposures can be identified during early adolescence, and 3) intrauterine substance exposure effects may differ from those associated with adolescents' own drug use.

Developing a Group Motivational Interviewing Intervention for Adolescents At-Risk for Developing an Alcohol or Drug use Disorder

This study examined how teens who had committed a first-time alcohol or other drug (AOD) offense responded to a motivational interviewing (MI) group intervention. Participants were 101 first-time AOD adolescent offenders (M=15.88; 63% male, 54% Hispanic). We developed and tested a six-session curriculum called Free Talk and solicited feedback from different teens after each session. Groups were recorded and transcribed. Feedback was categorized using the Motivational Interviewing Treatment Integrity scale (MITI 3.0). Feedback indicated high levels of evocation, collaboration, autonomy/support, and empathy. The current study highlights that utilizing group MI can be an acceptable approach for at-risk youth.

A Multilevel Developmental Contextual Approach To Substance Use and Addiction

Emerging technological advances in genetics and neuroscience have spawned innovative or elaborated conceptual models in the field of addiction science, as well as contributed to the mushrooming of new knowledge. By addictions, reference is made to chronic, often relapsing disorders typified by obsession, compulsion, or physical or psychological dependence. In this article it is proposed that a multilevel developmental contextual approach to substance use and addictions provides a useful framework for integrating existing studies across disciplines and serving as a generative guide to intriguing novel research questions. The multilevel developmental contextual approach emphasizes multiple factor influences on substance use and addiction, the conjoint influence of variables from different levels of analysis (e.g., genetic, biochemical, physiological, cognitive, social, neighborhood, societal), and dynamic, probabilistic behavior-outcome relations (i.e., the occurrence as well as the nature of expression of substance problems and addiction depend on a range of emerging, interactive factors that may vary across individuals and across time). The approach is illustrated with a long-term prospective study of predictors of binge drinking from adolescence to young adulthood and a description of the role of brain processes and mechanisms involved in the development and expression of alcohol use during adolescence.

Gender differences in factors influencing alcohol use and drinking progression among adolescents

While prevalence rates for alcohol use and related disorders differ widely between adult men and women, male and female adolescents do not exhibit the same disparity in alcohol consumption. Previous research and reviews do not address the emergence of differences in drinking patterns that occur during late adolescence. Therefore, a developmental perspective is presented for understanding how various risk and protective factors associated with problematic drinking affect diverging alcohol trajectories as youth move into young adulthood. This review examines factors associated with risk for developing an alcohol use disorder in adolescent girls and boys separately. Findings indicate that certain biological (i.e., genetic risk, neurological abnormalities associated with P300 amplitudes) and psychosocial (i.e., impact of positive drinking expectancies, personality characteristics, and deviance proneness) factors appear to impact boys and girls similarly. In contrast, physiological and social changes particular to adolescence appear to differentially affect boys and girls as they transition into adulthood. Specifically, boys begin to manifest a constellation of factors that place them at greater risk for disruptive drinking: low response to alcohol, later maturation in brain structures and executive function, greater estimates of perceived peer alcohol use, and socialization into traditional gender roles. On an individual level, interventions which challenge media-driven stereotypes of gender roles while simultaneously reinforcing personal values are suggested as a way to strengthen adolescent autonomy in terms of healthy drinking decisions. Moreover, parents and schools must improve consistency in rules and consequences regarding teen drinking across gender to avoid mixed messages about acceptable alcohol use for boys and girls.

Preventive interventions addressing underage drinking: state of the evidence and steps toward public health impact

The epidemiological features of underage drinking and evidence of its social, health, and economic consequences suggest compelling reasons for the development and dissemination of effective preventive interventions. To clarify the nature and extent of the current evidence base on preventive interventions addressing underage drinking, a review of the literature was conducted through extensive searches of the research literature on outcome evaluations, existing reviews of this body of outcome research (N = 25), and summary reports of evidence on specific interventions. More than 400 interventions were identified and screened, and the evidence for 127 was reviewed. Criteria for the evaluation of evidence were established for intervention studies with alcohol-specific outcome measures for 3 developmental periods (< 10, 10-15, and 16 to > or = 20 years of age). Ultimately, 12 interventions met criteria for "most promising" evidence and 29 met criteria for "mixed or emerging" evidence. Conducting this review revealed clear advances in the number of evidence-based interventions available and the quality of outcome research; however, much work remains to achieve greater public health impact through evidence-based interventions. This work should consider (1) the great need for intervention research related to understudied developmental phases, intervention domains (eg, family, school, community, and media), and populations (eg, early tweens, late teens, young adults not attending college, and nonmajority populations); (2) the critical importance of addressing key issues in research design and methods (eg, limited longitudinal studies, replication studies, and dissemination research); and (3) the need for improved consistency in application of evidence and reporting standards. Finally, we recommend the application of emerging consumer-oriented and community-participatory models for intervention development and research, designed to increase the likelihood of "real-world" public health impact through improved translation of intervention science into practice.

Transitions into underage and problem drinking: developmental processes and mechanisms between 10 and 15 years of age

Numerous developmental changes occur across levels of personal organization (eg, changes related to puberty, brain and cognitive-affective structures and functions, and family and peer relationships) in the age period of 10 to 15 years. Furthermore, the onset and escalation of alcohol use commonly occur during this period. This article uses both animal and human studies to characterize these multilevel developmental changes. The timing of and variations in developmental changes are related to individual differences in alcohol use. It is proposed that this integrated developmental perspective serve as the foundation for subsequent efforts to prevent and to treat the causes, problems, and consequences of alcohol consumption.

Diffusion tensor measures of the corpus callosum in adolescents with adolescent onset alcohol use disorders

BACKGROUND

In adults, myelination injury is associated with alcoholism. Maturation of the corpus callosum is prominent during adolescence. We hypothesized that subjects with adolescent-onset alcohol use disorders (AUD; defined as Diagnostic and Statistical Manual of Mental Disorders-IV alcohol dependence or abuse) would have myelination microstructural differences compared to controls.

METHODS

Adolescent subjects (25 males, 7 females) with an AUD (16.9 +/- 1.2 years), who were recruited from substance abuse treatment programs and had co-morbid mental disorders, and 28 sociodemographically similar healthy controls (17 males, 11 females; 15.9 +/- 1.1 years) underwent a 3.0 T MRI diffusion tensor imaging scan.

RESULTS

Measures of rostral body fractional anisotropy (FA) were higher in the AUD group than in the control group. Compared to controls, mean diffusivity (MD) was lower, while FA was higher, in the AUD group in the isthmus region. Anterior corpus callosum microstructural development differed in adolescents with AUD, as age was positively (not negatively) associated with rostrum MD and age was negatively (not positively) associated with rostrum FA. There were sex by group interactions in that control females had higher posterior midbody FA when compared to female adolescents with AUD.

CONCLUSIONS

Lower MD and higher FA values in the AUD group suggest pre-morbid vulnerability for accelerated prefrontal and temporo-parietal myelin maturation that may enhance the risk for adolescent AUD. Significant (and opposite to developmentally expected) correlations were seen between anterior corpus callosum MD and FA measures and age in the AUD group, suggesting neurotoxic effects of alcohol on adolescent corpus callosum microstructure. As seen in adults, female adolescents with AUD may be especially vulnerable to corpus callosum microstructural injury. Further diffusion tensor imaging studies of corpus callosum maturation in children at familial risk for alcoholism, and in those with AUD, need to be done to elucidate these mechanisms.

Robust and stable drinking behavior following long-term oral alcohol intake in rhesus macaques

Face validity in animal models of alcohol abuse and dependence is often at odds with robust demonstrations of ethanol-seeking. This study determined the relative influence of ethanol and a flavorant in maintaining ethanol intake in a nonhuman primate model of "cocktail" drinking. Four-year-old male monkeys were maintained on a 6% ethanol/6% Tang solution made available in daily (M-F) 1-h sessions. Experiments determined the effect of (1) a second daily access session, (2) concurrent presentation of the Tang vehicle, (3) sequential presentation of the vehicle in the first daily session and the ethanol solution in the second session, (4) altering the Tang concentration, (5) altering the ethanol concentration, and (6) removal of the flavorant. Mean daily intake (2.7+/-0.2 g/kg/day) was stable over 7 months. Simultaneous availability of a large, but not a low-moderate, volume of the vehicle reduced ethanol intake by about 50%. Decreasing the concentration of Tang in the first daily session reduced ethanol intake, whereas intake of the standard solution was increased in the second session. Ethanol consumption was decreased by only 27% when the flavorant was removed. In summary, alterations that reduced intake in the first daily session resulted in compensatory increases in ethanol intake in the second session, suggesting that animals sought a specific level of ethanol intake per day. It is concluded that models with excellent face validity (flavored beverages) can produce reliable ethanol intake in patterns that are highly consistent with ethanol-seeking behavior.

Differential expression of ethanol-induced hypothermia in adolescent and adult rats induced by pretest familiarization to the handling/injection procedure

BACKGROUND

Previous work examining ethanol's autonomic effects has found contrasting patterns of age-related differences in ethanol-induced hypothermia between adolescent and adult rats. Most studies have found adolescents to be less sensitive than adults to this effect, although other work has indicated that adolescents may be more sensitive than adults under certain testing conditions. To test the hypothesis that adolescents show more ethanol hypothermia than adults when the amount of disruption induced by the test procedures is low, but less hypothermia when the experimental perturbation is greater, the present study examined the consequences of manipulating the amount of perturbation at the time of testing on ethanol-induced hypothermia in adolescent and adult rats.

METHODS

The amount of test disruption was manipulated by administering ethanol through a chronically indwelling gastric cannula (low perturbation) versus via intragastric intubation (higher perturbation) in Experiment 1 or by either familiarizing animals to the handling and injection procedure for several days pretest or leaving them unmanipulated before testing in Experiment 2.

RESULTS

The results showed that the handling manipulation, but not the use of gastric cannulae, altered the expression of ethanol-induced hypothermia differentially across age. When using a familiarization protocol sufficient to reduce the corticosterone response to the handling and injection procedure associated with testing, adolescents showed greater hypothermia than adults. In contrast, the opposite pattern of age differences in hypothermia was evident in animals that were not manipulated before the test day. Surprisingly, however, this difference across testing circumstances was driven by a marked reduction in hypothermia among adults who had been handled before testing, with handling having relatively little impact on ethanol hypothermia among adolescents.

CONCLUSIONS

Observed differences between adolescents and adults in the autonomic consequences of ethanol were dramatically influenced by whether animals were familiarized with the handling/injection process before testing. Under these circumstances, adolescents were less susceptible than adults to the impact of experimental perturbation on ethanol-induced hypothermia. These findings suggest that seemingly innocuous aspects of experimental design can influence conclusions reached on ontogenetic differences in sensitivity to ethanol, at least when indexed by ethanol-induced hypothermia.

Adolescence and the Trajectory of Alcohol Use: Basic to Clinical Studies

Emerging findings from developmentally focused research indicates subtle but important neurocognitive disadvantages among adolescents with alcohol-use disorders (AUD) as compared to teens without AUD. Even after 3 weeks of abstinence AUD youth display a 10% decrement in delayed memory functions. Neuropsychological testing of youth followed at 4 and 8 years demonstrates that heavy drinking during adolescence is associated with diminished retrieval of verbal and nonverbal material, and poorer performance on tests requiring attention skills. Alcohol withdrawal over the teen years appears to uniquely contribute to deterioration in functioning in visuospatial tasks. Brain imaging studies suggest reduced hippocampal volumes, white matter microstructure irregularities, brain response abnormalities while performing challenging cognitive tasks, and enhanced brain response when viewing alcohol cues (i.e., alcohol advertisements) among adolescents with AUD. Family characteristics such as history of alcoholism and socioeconomic status as well as personal features, including adolescent psychopathology, gender, and age of onset must be carefully considered when investigating the influence of teenage drinking on neurocognition. Further research is needed to understand how age at onset of drinking and duration of abstinence at the time of assessment affect cognitive findings. Longitudinal studies are needed to clarify neuromaturational changes associated with early alcohol exposure and patterns of resiliency. Although the magnitude of alcohol-related effects observed in adolescents' neurocognition is relatively modest, the implications are major given the prevalence of alcohol involvement, and the important educational, occupational, and social transitions that occur during adolescence.