Controversies about the enhanced vulnerability of the adolescent brain to develop addiction

The Associations Between Social Support and Problematic Mobile Phone Use Among Children and Adolescents: A Three-level Meta-analysis

Numerous studies have investigated the relationship between social support and problematic mobile phone use among adolescents, yet a definitive consensus remains elusive. The high prevalence of problematic mobile phone use among children and adolescents requires urgent clarity on this issue. However, previous meta-analyses on this topic have primarily focused on college students, overlooking this association in younger age groups. The present study thus concentrated on children and adolescents, conducting a three-level meta-analysis to combine existing research findings and analyze various moderators to identify sources of research heterogeneity. A systematic literature search retrieved a total of 33 studies with 135 effect sizes for this meta-analysis, and 25,537 students (53.83% female, age range 7-19, grades range 3rd-12th) were included. The results showed a negative correlation (r = -0.139) between social support and problematic mobile phone use in children and adolescents. Age, social support measurement, sources of social support, and symptoms of problematic mobile phone use were found to have a significant moderating influence. Specifically, social support showed a stronger negative correlation with problematic mobile phone use in older adolescents compared to their younger counterparts. The correlation was more pronounced when using the Multidimensional Scale of Perceived Social Support than other scales. Family support exhibited a stronger negative correlation with problematic mobile phone use compared to other sources of support. Among the symptoms of problematic mobile phone use, the inability to control craving has the strongest negative correlation with social support. This meta-analysis suggested that providing more social support, particularly in the form of family support, during the development of children and adolescents may help alleviate problematic mobile phone use.

Liver disease in adolescents

In this article, we discuss common liver diseases in the adolescent population. We describe the initial evaluation of an adolescent presenting with new-onset liver enzyme abnormalities, based on the clinical history and physical examination. The management approach to the adolescent with liver disease is exemplified, including monitoring for adherence, risk-taking behaviours and focusing on psychosocial aspects of their care. Finally, we highlight the challenges of caring for the adolescent patient and the importance of addressing not only the liver disease but, more importantly, the holistic approach towards their management.

Nicotine on the developing brain

Developmental periods such as gestation and adolescence have enhanced plasticity leaving the brain vulnerable to harmful effects from nicotine use. Proper brain maturation and circuit organization is critical for normal physiological and behavioral outcomes. Although cigarette smoking has declined in popularity, noncombustible nicotine products are readily used. The misperceived safety of these alternatives lead to widespread use among vulnerable populations such as pregnant women and adolescents. Nicotine exposure during these sensitive developmental windows is detrimental to cardiorespiratory function, learning and memory, executive function, and reward related circuitry. In this review, we will discuss clinical and preclinical evidence of the adverse alterations in the brain and behavior following nicotine exposure. Time-dependent nicotine-induced changes in reward related brain regions and drug reward behaviors will be discussed and highlight unique sensitivities within a developmental period. We will also review long lasting effects of developmental exposure persisting into adulthood, along with permanent epigenetic changes in the genome which can be passed to future generations. Taken together, it is critical to evaluate the consequences of nicotine exposure during these vulnerable developmental windows due to its direct impact on cognition, potential trajectories for other substance use, and implicated mechanisms for the neurobiology of substance use disorders.

Reversing anterior insular cortex neuronal hypoexcitability attenuates compulsive behavior in adolescent rats

Development of self-regulatory competencies during adolescence is partially dependent on normative brain maturation. Here, we report that adolescent rats as compared to adults exhibit impulsive and compulsive-like behavioral traits, the latter being associated with lower expression of mRNA levels of the immediate early gene zif268 in the anterior insula cortex (AIC). This suggests that underdeveloped AIC function in adolescent rats could contribute to an immature pattern of interoceptive cue integration in decision making and a compulsive phenotype. In support of this, we report that layer 5 pyramidal neurons in the adolescent rat AIC are hypoexcitable and receive fewer glutamatergic synaptic inputs compared to adults. Chemogenetic activation of the AIC attenuated compulsive traits in adolescent rats supporting the idea that in early stages of AIC maturity there exists a suboptimal integration of sensory and cognitive information that contributes to inflexible behaviors in specific conditions of reward availability.

The association between age of initiation and current blunt use among adults: Findings from the national survey on drug use and health, 2014-2019

BACKGROUND

Initiating cannabis use at a young age has been linked to problematic and continued cannabis use in adulthood. Given that approximately 1 in 3 adult cannabis smokers report blunt use, it is important to determine if and how age of blunt initiation is associated with current blunt use among adult blunt smokers.

METHODS

This study uses cross-sectional pooled data from the 2014-2019 National Survey on Drug Use and Health (NSDUH) to examine the association between age of blunt initiation and current blunt use among 62,020 adults who reported lifetime blunt use.

RESULTS

Among lifetime blunt smokers, 51.4% initiated blunt use at 18 years or older, 42.1% initiated blunt use at 14-17 years old and 6.5% initiated blunt use at 13 years or younger. Multivariable logistic regression models revealed that odds of past 12-month (aOR: 1.58; 95% CI: 1.45 - 1.72), past 30-day (aOR: 2.58; 95% CI: 2.37 - 2.80) and daily (aOR: 3.17; 95% CI: 2.61 - 3.86) blunt use were greater among adults who initiated blunt use at 13 years of age or younger relative to those who initiated blunt use at 18 years of age or older, controlling for covariates.

CONCLUSIONS

Early onset of blunt use among adolescents is associated with current blunt use in adulthood among lifetime blunt users. Given the adverse health effects associated with blunt use and the prevalence of adult cannabis users who report blunt use, cannabis interventions and policies should be expanded to target blunt use among early initiators.

Factors modulating the incubation of drug and non-drug craving and their clinical implications

It was suggested in 1986 that cue-induced cocaine craving increases progressively during early abstinence and remains high during extended periods of time. Clinical evidence now supports this hypothesis and that this increase is not specific to cocaine but rather generalize across several drugs of abuse. Investigators have identified an analogous incubation phenomenon in rodents, in which time-dependent increases in cue-induced drug seeking are observed after abstinence from intravenous drug or palatable food self-administration. Incubation of craving is susceptible to variation in magnitude as a function of biological and/or the environmental circumstances surrounding the individual. During the last decade, the neurobiological correlates of the modulatory role of biological (sex, age, genetic factors) and environmental factors (environmental enrichment and physical exercise, sleep architecture, acute and chronic stress, abstinence reinforcement procedures) on incubation of drug craving has been investigated. In this review, we summarized the behavioral procedures adopted, the key underlying neurobiological correlates and clinical implications of these studies.

Multifactorial Etiology of Adolescent Nicotine Addiction: A Review of the Neurobiology of Nicotine Addiction and Its Implications for Smoking Cessation Pharmacotherapy

Nicotine is the primary pharmacologic component of tobacco, and its highly addictive nature is responsible for its widespread use and significant withdrawal effects that result in challenges to smoking cessation therapeutics. Nicotine addiction often begins in adolescence and this is at least partially attributed to the fact that adolescent brain is most susceptible to the neuro-inflammatory effects of nicotine. There is increasing evidence for the involvement of microglial cells, which are the brain's primary homeostatic sensor, in drug dependence and its associated behavioral manifestations particularly in the adolescent brain. A hallmark of neuro-inflammation is microglial activation and activation of microglia by nicotine during adolescent development, which may result in long-term addiction to nicotine. This non-systematic review examines multifactorial etiology of adolescent nicotine addiction, neurobiology of nicotine addiction and the potential mechanisms that underlie the effects of nicotine on inflammatory signaling in the microglia, understanding how nicotine affects the adolescent brain. We speculate, that modulating homeostatic balance in microglia, could have promising therapeutic potential in withdrawal, tolerance, and abstinence-related neural adaptations in nicotine addiction, in the adolescent brain. Further, we discuss nicotine addiction in the context of the sensitization-homeostasis model which provides a theoretical framework for addressing the potential role of microglial homeostasis in neural adaptations underlying nicotine abuse.

Neurotoxicity of e-cigarettes

It appears that electronic cigarettes (EC) are a less harmful alternative to conventional cigarette (CC) smoking, as they generate substantially lower levels of harmful carcinogens and other toxic compounds. Thus, switching from CC to EC may be beneficial for smokers. However, recent accounts of EC- or vaping-associated lung injury (EVALI) has raised concerns regarding their adverse health effects. Additionally, the increasing popularity of EC among vulnerable populations, such as adolescents and pregnant women, calls for further EC safety evaluation. In this state-of-the-art review, we provide an update on recent findings regarding the neurological effects induced by EC exposure. Moreover, we discuss possible neurotoxic effects of nicotine and numerous other chemicals which are inherent both to e-liquids and EC aerosols. We conclude that in recognizing pertinent issues associated with EC usage, both government and scientific researchers must address this public health issue with utmost urgency.

Access to voluntary running wheel exercise: Prevention of anxiety-like behavior in chronically stressed rats, but potentiation of ethanol intake/preference

The current study tested the effect of voluntary running on future anxiety-like behavior, physiological response to stress, and ethanol intake/preference, while including a chronically stressed group and healthy group housed conspecifics. When given concurrently, voluntary running reduces ethanol intake, though it is unknown what effect voluntary running will have on anxiety-like behavior, corticosterone response to stress, and ethanol intake/preference when exercise is allowed only prior to ethanol access. Adolescent male Long Evans rats arrived in the lab at postnatal day (PND) 21. At PND 27, rats were either socially isolated (SI; n = 1/cage) or group housed (GH; n = 4/cage). Half of each group was allowed access to a running wheel for 30 min for 24 days from PND 35-66, and half of each group was not allowed access to a running wheel. After the housing/running procedure, we tested anxiety-like behavior using the elevated plus maze and stress responsivity by measuring corticosterone (CORT) levels before and after a swim stressor; then, rats were allowed intermittent access to ethanol in two-bottle choice design for four weeks. In accord with our hypothesis, running reduced anxiety-like behavior in SI runners compared to non-runners. Swim stress increased CORT levels but there was no difference in the response among groups. In regard to ethanol intake and preference, running (irrespective of housing group) increased intake at the 30 min time point and preference at the 24 h time point. Altogether, these data show that access to voluntary exercise was successful in reducing anxiety-like behavior, but withdrawal of exercise access appeared to enhance ethanol intake/preference. We suggest that these data reflect hedonic substitution.

Prefrontal cortex development and emergence of self-regulatory competence: the two cardinal features of adolescence disrupted in context of alcohol abuse

Adolescence is a tumultuous period in the lifetime of an individual confronted to major changes in emotional, social and cognitive appraisal. During this period of questioning and doubt, while the executive functions are still maturing, the abstract reasoning remains vague and the response inhibition loose; ultimately the adolescent scarcely resists temptation. Consequently, adolescence is often associated with uninhibited risk-taking, reckless behaviours, among which are alcohol and illicit drugs use. Here, we discuss how the development of the prefrontal cortex (which critically contributes to rational decision-making and temporal processing of complex events) can be associated with the idiosyncratic adolescent behaviour, and potentially uncontrolled alcohol use. Most importantly, we present clinical and preclinical evidence supporting that ethanol exposure has deleterious effects on the adolescent developing brain. Ultimately, we discuss why a late maturing prefrontal cortex represents a ripe candidate to environmental influences that contribute to shape the adolescent brain but, potentially, can also trigger lifelong maladaptive responses, including increased vulnerability to develop substance use disorder later in life.

Subregional Hippocampal Thickness Abnormalities in Older Adults with a History of Heavy Cannabis Use

Background and Aims: Legalization of cannabis (CB) for both medicinal and, in some states, recreational use, has given rise to increasing usage rates across the country. Of particular concern are indications that frequent CB use may be selectively harmful to the developing adolescent brain compared with adult-onset usage. However, the long-term effects of heavy, adolescent CB use on brain structure and cognitive performance in late-life remain unknown. A critical brain region is the hippocampus (HC), where there is a striking intersection between high concentrations of cannabinoid 1 (CB1) receptors and age-related pathology.

Design: We investigated whether older adults (average age=66.6+7.2 years old) with a history of early life CB use show morphological differences in hippocampal subregions compared with older, nonusers.

Methods: We performed high-resolution magnetic resonance imaging combined with computational techniques to assess cortical thickness of the medial temporal lobe, neuropsychological testing, and extensive drug use histories on 50 subjects (24 formerly heavy cannabis users [CB+ group] abstinent for an average of 28.7 years, 26 nonusers [CB− group]). We investigated group differences in hippocampal subregions, controlling for age, sex, and intelligence (as measured by the Wechsler Test of Adult Reading), years of education, and cigarette use.

Results: The CB+ subjects exhibited thinner cortices in subfields cornu ammonis 1 [CA1; F(1,42)=9.96, p=0.0003], and CA2, 3, and the dentate gyrus [CA23DG; F(1,42)=23.17, p<0.0001], and in the entire HC averaged over all subregions [F(1,42)=8.49, p=0.006].

Conclusions: Negative effects of chronic adolescent CB use on hippocampal structure are maintained well into late life. Because hippocampal cortical loss underlies and exacerbates age-related cognitive decline, these findings have profound implications for aging adults with a history of early life usage.

Clinical Trial Registration: ClinicalTrials.gov # NCT01874886.

Juvenile stress induces behavioral change and affects perineuronal net formation in juvenile mice

Background

Many neuropsychiatric disorders develop in early life. Although the mechanisms involved have not been elucidated, it is possible that functional abnormalities of parvalbumin-positive interneurons (PV neurons) are present. Several previous studies have shown that juvenile stress is implicated in the development of neuropsychiatric disorders. We aimed to clarify the effects of juvenile stress on behavior and on the central nervous system. We investigated behavioral abnormalities of chronically-stressed mice during juvenilehood and the effect of juvenile stress on PV neurons and WFA-positive perineuronal nets (PNNs), which are associated with vulnerability and plasticity in the mouse brain.

Results

Due to juvenile stress, mice showed neurodevelopmental disorder-like behavior. Juvenile stressed mice did not show depressive-like behaviors, but on the contrary, they showed increased activity and decreased anxiety-like behavior. In the central nervous system of juvenile stressed mice, the fluorescence intensity of WFA-positive PNNs decreased, which may signify increased vulnerability.

Conclusion

This study suggested that juvenile stressed mice showed behavioral abnormalities, resembling those seen in neuropsychiatric disorders, and increased brain vulnerability.

The Relationship between Self-Reported Executive Functioning and Risk-Taking Behavior in Urban Homeless Youth

Introduction: Almost 2 million U.S. youth are estimated to live on the streets, in shelters, or in other types of temporary housing at some point each year. Both their age and living situations make them more likely to engage in high-risk behaviors, particularly during adolescence, a time of increased risk taking. Much of self-control appears related to the development of the prefrontal cortex, which is at a particularly crucial period of elaboration and refinement during adolescence and emerging adulthood. Executive processes like decision-making, inhibition, planning, and reasoning may be vulnerable to adversity experienced as a result of homelessness and related impoverishment during childhood and adolescence. No study to date, to our knowledge, has directly investigated differences in risk-taking by homeless youth as it relates to their developing executive control. Objective: Examine the relationship between the level of self-reported executive function (EF) and engagement in risk taking behaviors among a sample of shelter-living urban homeless youth. We predicted that homeless youth who have lower levels of self-reported EF would more readily engage in risky behaviors that could lead to negative outcomes. Participants: One hundred and forty-nine youths between 18 and 22 years of age were recruited from homeless agencies in Chicago. Of this study sample, 53% were female and 76% African American. Measures: All participants completed, as part of a broader neuropsychological assessment, the Behavior Rating Inventory of Executive Functioning-Adult Version (BRIEF-A), the National Youth Risk Behavior Survey (YRBS), and the Mini-International Neuropsychiatric Interview (MINI). Analyses: Groups were separated based on level of self-reported EF, with two groups identified: High self-reported EF fell >1 SD above the normative average, and low self-reported EF fell >1 SD below the normative average. All analyses utilized Chi-square and Mann-Whitney tests. Results and Conclusions: Analyses revealed a relationship between the level of self-reported EF and risk taking behaviors in this group of sheltered homeless urban youths. Those with lower self-reported executive functioning had higher rates of engagement in multiple substance-related risk taking behaviors. These findings are important because they are a first step towards identifying contributions to risk-taking behavior in urban homeless youths. Identifying potential factors like low self-reported EF better allows us to potentially intervene, thereby providing focused support to youths who are at higher risk for engaging in problematic behaviors.

Adolescent Maturational Transitions in the Prefrontal Cortex and Dopamine Signaling as a Risk Factor for the Development of Obesity and High Fat/High Sugar Diet Induced Cognitive Deficits

Adolescence poses as both a transitional period in neurodevelopment and lifestyle practices. In particular, the developmental trajectory of the prefrontal cortex (PFC), a critical region for behavioral control and self-regulation, is enduring, not reaching functional maturity until the early 20 s in humans. Furthermore, the neurotransmitter dopamine is particularly abundant during adolescence, tuning the brain to rapidly learn about rewards and regulating aspects of neuroplasticity. Thus, adolescence is proposed to represent a period of vulnerability towards reward-driven behaviors such as the consumption of palatable high fat and high sugar diets. This is reflected in the increasing prevalence of obesity in children and adolescents as they are the greatest consumers of “junk foods”. Excessive consumption of diets laden in saturated fat and refined sugars not only leads to weight gain and the development of obesity, but experimental studies with rodents indicate they evoke cognitive deficits in learning and memory process by disrupting neuroplasticity and altering reward processing neurocircuitry. Consumption of these high fat and high sugar diets have been reported to have a particularly pronounced impact on cognition when consumed during adolescence, demonstrating a susceptibility of the adolescent brain to enduring cognitive deficits. The adolescent brain, with heightened reward sensitivity and diminished behavioral control compared to the mature adult brain, appears to be a risk for aberrant eating behaviors that may underpin the development of obesity. This review explores the neurodevelopmental changes in the PFC and mesocortical dopamine signaling that occur during adolescence, and how these potentially underpin the overconsumption of palatable food and development of obesogenic diet-induced cognitive deficits.

Behavioral consequences of exposure to a high fat diet during the post-weaning period in rats

We explored the impact of exposure to an obesogenic diet (High Fat-High Sucrose; HFS) during the post-weaning period on sweet preference and behaviors linked to reward and anxiety. All rats were fed chow. In addition a HFS-transient group had access to this diet for 10days from post-natal (PN) day 22 and a HFS-continuous group continued access until adult. Behavioral tests were conducted immediately after PN 32 (adolescence) or after PN 60 (adult) and included: the condition place preference (CPP) test for chocolate, sugar and saccharin preference (anhedonia), the elevated plus maze (anxiety-like behavior) and the locomotor response to quinpirole in the open field. Behavior was unaltered in adult rats in the HFS-transient group, suggesting that a short exposure to this obesogenic food does not induce long-term effects in food preferences, reward perception and value of palatable food, anxiety or locomotor activity. Nevertheless, rats that continued to have access to HFS ate less chocolate during CPP training and consumed less saccharin and sucrose when tested in adolescence, effects that were attenuated when these rats became adult. Moreover, behavioral effects linked to transient HFS exposure in adolescence were not sustained if the rats did not remain on that diet until adult. Collectively our data demonstrate that exposure to fat and sucrose in adolescence can induce immediate reward hypofunction after only 10days on the diet. Moreover, this effect is attenuated when the diet is extended until the adult period, and completely reversed when the HFS diet is removed.

Novelty Seeking and Drug Addiction in Humans and Animals: From Behavior to Molecules

Global treatment of drug addiction costs society billions of dollars annually, but current psychopharmacological therapies have not been successful at desired rates. The increasing number of individuals suffering from substance abuse has turned attention to what makes some people more vulnerable to drug addiction than others. One personality trait that stands out as a contributing factor is novelty seeking. Novelty seeking, affected by both genetic and environmental factors, is defined as the tendency to desire novel stimuli and environments. It can be measured in humans through questionnaires and in rodents using behavioral tasks. On the behavioral level, both human and rodent studies demonstrate that high novelty seeking can predict the initiation of drug use and a transition to compulsive drug use and create a propensity to relapse. These predictions are valid for several drugs of abuse, such as alcohol, nicotine, cocaine, amphetamine, and opiates. On the molecular level, both novelty seeking and addiction are modulated by the central reward system in the brain. Dopamine is the primary neurotransmitter involved in the overlapping neural substrates of both parameters. In sum, the novelty-seeking trait can be valuable for predicting individual vulnerability to drug addiction and for generating successful treatment for patients with substance abuse disorders.

Neurobiology of Adolescent Substance Use Disorders

There are many facets of the neurobiology of substance use that are distinct in adolescence as compared with adulthood. The adolescent brain is subject to intense subcortical reward processes, but is left with an immature prefrontal control system that is often unable to resist the pull of potentially exciting activities like substance use, even when fully aware of the dangers involved. Peer influences serve only to magnify these effects and foster more sensation-seeking, risky behavior. The unique aspects of neurobiology should be taken into consideration when designing prevention programs and clinical interventions for adolescent substance use disorders.

Acute acquired comitant esotropia related to excessive Smartphone use

Background

To describe the clinical characteristics and outcomes of acute acquired comitant esotropia (AACE) related to excessive smartphone use in adolescents.

Methods

The medical records of 12 patients with AACE and a history of excessive smartphone use were retrospectively reviewed, and the duration of smartphone use, angle of deviation, refractive error, stereopsis, and treatment options were analyzed.

Results

All patients showed convergent and comitant esotropia ranging from 15 to 45 prism diopters (PD; average: 27.75 ± 11.47 PD) at far fixation. The angle of deviation was nearly equivalent for far and near fixation. Every patient used a smartphone for more than 4 h a day over a period of several months (minimum 4 months). Myopic refractive errors were detected in eight patients (average:−3.84 ± 1.68 diopters (D]), and the remaining four patients showed mild hyperopic refractive error (average: +0.84 ± 0.53 D). Reductions in esodeviation were noted in all patients after refraining from smartphone use, and bilateral medial rectus recession was performed in three patients with considerable remnant esodeviation. Postoperative exams showed orthophoria with good stereoacuity in these patients.

Conclusion

Excessive smartphone use might influence AACE development in adolescents. Refraining from smartphone use can decrease the degree of esodeviation in these patients, and remnant deviation can be successfully managed with surgical correction.

Adolescent Life History Strategy in the Intergenerational Transmission and Developmental Stability of Substance Use

Research suggests that fast life history strategy (LHS) may be a primary driver of substance use among young adults. However, a recent study reported that (a) young adult fast LHS did not subsume all theorized indicators of LHS during this period and (b) fast LHS among parents did not predict young adult fast LHS or liability for use of common substances. In this study, we used structural equations and national data to test whether these findings generalized to adolescence. In addition, given that LHS and substance use share genetic and neuropsychological bases, we examined whether fast LHS could explain the developmental stability of substance use. Overall, our results extend the findings discussed above and suggest that fast LHS fully explains the developmental stability of substance use among youth. We discuss implications for life history models, research applying life history theory and substance use, and substance abuse prevention and treatment.

Effects of Cannabinoid Exposure during Adolescence on the Conditioned Rewarding Effects of WIN 55212-2 and Cocaine in Mice: Influence of the Novelty-Seeking Trait

Adolescent exposure to cannabinoids enhances the behavioural effects of cocaine, and high novelty-seeking trait predicts greater sensitivity to the conditioned place preference (CPP) induced by this drug. Our aim was to evaluate the influence of novelty-seeking on the effects of adolescent cannabinoid exposure. Adolescent male mice were classified as high or low novelty seekers (HNS and LNS) in the hole-board test. First, we evaluated the CPP induced by the cannabinoid agonist WIN 55212-2 (0.05 and 0.075 mg/kg, i.p.) in HNS and LNS mice. Then, HNS and LNS mice were pretreated i.p. with vehicle, WIN 55212-2 (0.1 mg/kg), or cannabinoid antagonist rimonabant (1 mg/kg) and were subsequently conditioned with WIN 55212-2 (0.05 mg/kg, i.p.) or cocaine (1 or 6 mg/kg, i.p.). Only HNS mice conditioned with the 0.075 mg/kg dose acquired CPP with WIN 55212-2. Adolescent exposure to this cannabinoid agonist increased the rewarding effects of 1 mg/kg of cocaine in both HNS and LNS mice, and in HNS mice it also increased the reinstating effect of a low dose of cocaine. Our results endorse a role for individual differences such as a higher propensity for sensation-seeking in the development of addiction.

Nicotine and the adolescent brain

Adolescence encompasses a sensitive developmental period of enhanced clinical vulnerability to nicotine, tobacco, and e-cigarettes. While there are sociocultural influences, data at preclinical and clinical levels indicate that this adolescent sensitivity has strong neurobiological underpinnings. Although definitions of adolescence vary, the hallmark of this period is a profound reorganization of brain regions necessary for mature cognitive and executive function, working memory, reward processing, emotional regulation, and motivated behavior. Regulating critical facets of brain maturation are nicotinic acetylcholine receptors (nAChRs). However, perturbations of cholinergic systems during this time with nicotine, via tobacco or e-cigarettes, have unique consequences on adolescent development. In this review, we highlight recent clinical and preclinical data examining the adolescent brain's distinct neurobiology and unique sensitivity to nicotine. First, we discuss what defines adolescence before reviewing normative structural and neurochemical alterations that persist until early adulthood, with an emphasis on dopaminergic systems. We review how acute exposure to nicotine impacts brain development and how drug responses differ from those seen in adults. Finally, we discuss the persistent alterations in neuronal signaling and cognitive function that result from chronic nicotine exposure, while highlighting a low dose, semi-chronic exposure paradigm that may better model adolescent tobacco use. We argue that nicotine exposure, increasingly occurring as a result of e-cigarette use, may induce epigenetic changes that sensitize the brain to other drugs and prime it for future substance abuse.

Correlates of experimentation with smoking and current cigarette consumption among adolescents

OBJECTIVE:

The aim of this study was to analyze social characteristics and stress as correlates of cigarette smoking in adolescence. The main intent was to identify elements that distinguish adolescents who had experimented with smoking and did not progress to regular smoking from those who became current smokers.

METHODS:

Students at 10 high schools in the city of Ribeirão Preto, Brazil, completed a questionnaire based on an instrument employed in a similar large-scale study. The students were classified as never-smokers or experimenters. The experimenters were subcategorized as having become current smokers or nonprogressors. Analyses were performed using adjusted logistic models.

RESULTS:

A total of 2,014 students (mean age, 16.2 ± 1.1 years; females, 53%) completed the questionnaire. We categorized 1,283 students (63.7%) as never-smokers, 244 (12.1%) as current smokers, and 487 (24.2%) as nonprogressors. We found that experimentation with smoking was associated with being held back a grade in school (OR = 1.80), alcohol intake (low/occasional, OR = 8.92; high/regular, OR = 2.64), illicit drug use (OR = 9.32), having a sibling or cousin who smokes (OR = 1.39), having a friend who smokes (OR = 2.08), and high levels of stress (in females only, OR = 1.32). Factors associated with an increased risk of transitioning from experimenter to current smoker were alcohol intake (low/occasional, OR = 3.28; high/regular, OR = 2.16), illicit drug use (OR = 3.61), and having a friend who smokes (OR = 7.20).

CONCLUSIONS:

Current smoking was associated with a profile of socioeconomic correlates different from that associated with experimentation only. Our data (showing that current smoking was associated with having a friend who smokes, alcohol intake, and illicit drug use) suggest the need for comprehensive approaches to discourage substance use during adolescence.

Longitudinal trajectories of marijuana use from adolescence to young adulthood

BACKGROUND

Marijuana use is increasingly widespread among adolescents and young adults; however, few studies have examined longitudinal trajectories of marijuana use during this important developmental period. As such, we examined adolescent trajectories of marijuana use and the psychosocial factors that may differentiate individuals who escalate their marijuana use over adolescence and young adulthood from those who do not.

METHODS

Participants were 1204 9th and 10th graders at baseline who were over-sampled for cigarette use and were followed over 6-years, as part of an extensive longitudinal study, the Social and Emotional Contexts of Adolescent Smoking Patterns (SECASP) study. Growth Mixture Modeling (GMM) was used to model trajectories of marijuana use and Mixed Effects Regression analyses were used to examine psychosocial correlates of marijuana use escalation over time.

RESULTS

Our results revealed three trajectories of non-escalating users (low users, medium users, and high users) and one escalating user trajectory. We found that relative to Non-escalators the Escalators had higher cigarette smoking (p<.0001), novelty-seeking (p=.02), aggressive and anti-social behavior (p<.007), and problem behavior related to peer context (p=.04). Moreover, there were important time and Group by Time interactions in some of these relationships. On the other hand, parental control and depression did not differ between escalators and low and medium non-escalating users.

CONCLUSIONS

Cigarette smoking, novelty-seeking, aggressive and anti-social behavior, and peer influence are related to 'escalating' marijuana use throughout adolescence and young adulthood.

Neural activation during response inhibition is associated with adolescents' frequency of risky sex and substance use

OBJECTIVE

INTRODUCTION

While many have identified the important role of the developing brain in youth risk behavior, few have examined the relationship between salient cognitive factors (response inhibition) and different types of real-world adolescent health risk behaviors such as substance use and risky sex, within the same sample of youth.

METHODS

We therefore sought to examine these relationships with 95 high-risk youth (ages 14-18; M age = 16.29 years). We examined blood oxygen level dependent (BOLD) response to an fMRI-based cognitive task designed to assess response inhibition (Go/NoGo) and past month risk behavior (number of substance use days; number of unprotected sex days).

RESULTS

For this sample of youth, we found significant negative correlations between past month substance use and response inhibition within the left inferior frontal gyrus (IFG) and right insula (uncorrected p < .001; extent threshold ≥ 10 voxels). In addition, in the same contrast, we found significant positive correlations between past month risky sex and activation within the right IFG and left middle occipital gyrus (uncorrected p < .001; extent threshold ≥ 10 voxels).

CONCLUSIONS

These results suggest the particular relevance of these regions in this compelling, albeit slightly different, pattern of response for adolescent risky behaviors.

Liver disease in the adolescent

This article discusses common liver diseases in the adolescent. Briefly reviewed is the evaluation of the adolescent with new-onset liver enzyme elevation. Then the article discusses common liver diseases, such as nonalcoholic fatty liver disease, hepatitis, metabolic disease, biliary atresia, cystic fibrosis, and inherited disorders of cholestasis. Finally, a management approach to the adolescent with liver disease is outlined, noting the challenges that must be addressed to effectively care for not only liver disease in the adolescent but also the patient as a whole.