Nucleus accumbens response to rewards and testosterone levels are related to alcohol use in adolescents and young adults

Neuronal biomarkers as potential therapeutic targets for drug addiction related to sex differences in the brain: Opportunities for personalized treatment approaches

Biological sex disparities manifest at various stages of drug addiction, including craving, substance abuse, abstinence, and relapse. These discrepancies are underpinned by notable distinctions in neurobiological substrates, encompassing brain structures, functions, and neurotransmitter systems implicated in drug addiction. Neuronal biomarkers, such as neurotransmitters, signaling proteins, and genes may be associated with the diagnosis, prognosis, and treatment outcomes in both biological sexes afflicted by drug abuse. Sex differences in the neural reward system, mainly through dopaminergic transmission during drug abuse, can be attributed to modifications in neurotransmitter systems and signaling pathways. This results in distinct patterns of neural activation and responsiveness to addictive substances in males and females. Sex hormones, the estrus/menstrual cycle, and cerebral neurochemistry contribute to the progression of psychological and physiological dependence in both male and female individuals grappling with addiction. Moreover, the alteration of sex hormone balance and neurotransmitter release plays a pivotal role in substance use disorders, subsequently modulating cognitive functions pertinent to reward, including memory formation, decision-making, and locomotor activity. Comparative investigations reveal distinctions in brain region volume, gene expression, neuronal firing, and circuitry in substance use disorders affecting individuals of both biological sexes. This review examines prevalent substance use disorders to elucidate the impact of sex hormones as therapeutic biomarkers on the mesocorticolimbic neurotransmitter systems via diverse mechanisms within the addicted brain. We underscore the imperative necessity of considering these variations to gain a deeper comprehension of addiction mechanisms and potentially discern sex-specific neuronal biomarkers for tailored therapeutic interventions.

Sex Differences in Alcohol Use: Is It All About Hormones?

Risky alcohol use and alcohol use disorders (AUD) are a rising problem in women, yet a major disparity in our understanding of what drives alcohol consumption in women remains. Historically biomedical research has focused on male subjects; however, recent increases in reporting of females, have highlighted major differences between the sexes. Here we review the current literature of the effect of gonadal steroid hormones (estrogens, androgens, and progestins), neurosteriods, and neurobiological factors on alcohol use in clinical and preclinical studies of both sexes. Further, we briefly discuss how fundamental sex differences in genetics, metabolism, neuroimmune, and stress responses may influence sex differences in alcohol intake. Comparing the sexes could aid in the discovery of novel therapeutics to treat AUD, and implementation of current treatment options in women.

Neural responses to reward, threat, and emotion regulation and transition to hazardous alcohol use

AIMS

Reward processing and regulation of emotions are thought to impact the development of addictive behaviors. In this study, we aimed to determine whether neural responses during reward anticipation, threat appraisal, emotion reactivity, and cognitive reappraisal predicted the transition from low-level to hazardous alcohol use over a 12-month period.

METHODS

Seventy-eight individuals aged 18-22 with low-level alcohol use [i.e. Alcohol Use Disorder Identification Test (AUDIT) score <7] at baseline were enrolled. They completed reward-based and emotion regulation tasks during magnetic resonance imaging to examine reward anticipation, emotional reactivity, cognitive reappraisal, and threat anticipation (in the nucleus accumbens, amygdala, superior frontal gyrus, and insula, respectively). Participants completed self-report measures at 3-, 6-, 9-, and 12-month follow-up time points to determine if they transitioned to hazardous use (as defined by AUDIT scores ≥8).

RESULTS

Of the 57 participants who completed follow-up, 14 (24.6%) transitioned to hazardous alcohol use. Higher baseline AUDIT scores were associated with greater odds of transitioning to hazardous use (odds ratio = 1.73, 95% confidence interval 1.13-2.66, P = .005). Brain activation to reward, threat, and emotion regulation was not associated with alcohol use. Of the neural variables, the amygdala response to negative imagery was numerically larger in young adults who transitioned to hazardous use (g = 0.31), but this effect was not significant.

CONCLUSIONS

Baseline drinking levels were significantly associated with the transition to hazardous alcohol use. Studies with larger samples and longer follow-up should test whether the amygdala response to negative emotional imagery can be used to indicate a future transition to hazardous alcohol use.

The role of neurosteroids in posttraumatic stress disorder and alcohol use disorder: A review of 10 years of clinical literature and treatment implications

Rates of alcohol use disorder (AUD) are increasing in men and women and there are high rates of concurrent posttraumatic stress disorder (PTSD) and AUD. AUD and PTSD synergistically increase symptomatology and negatively affect treatment outcomes; however, there are very limited pharmacological treatments for PTSD/AUD. Neurosteroids have been implicated in the underlying neurobiological mechanisms of both PTSD and AUD and may be a target for treatment development. This review details the past ten years of research on pregnenolone, progesterone, allopregnanolone, pregnanolone, estradiol, testosterone and dehydroepiandrosterone/dehydroepiandrosterone-sulfate (DHEA/DHEA-S) in the context of PTSD and AUD, including examination of trauma/alcohol-related variables, such as stress-reactivity. Emerging evidence that exogenous pregnenolone, progesterone, and allopregnanolone may be promising, novel interventions is also discussed. Specific emphasis is placed on examining the application of sex as a biological variable in this body of literature, given that women are more susceptible to both PTSD diagnoses and stress-related alcohol consumption.

Developmental shift in testosterone influence on prefrontal emotion control

A paradox of testosterone effects is seen in adolescents versus adults in social emotional approach-avoidance behavior. During adolescence, high testosterone levels are associated with increased anterior prefrontal (aPFC) involvement in emotion control, whereas during adulthood this neuro-endocrine relation is reversed. Rodent work shows that, during puberty, testosterone transitions from a neuro-developmental to a social-sexual activating hormone. In this study, we explored whether this functional transition is also present in human adolescents and young adults. Using a prospective longitudinal design, we investigated the role of testosterone on neural control of social emotional behavior during the transitions from middle to late adolescence and into young adulthood. Seventy-one individuals (tested at ages 14, 17, and 20 years) performed an fMRI-adapted approach-avoidance (AA) task involving automatic and controlled actions in response to social emotional stimuli. In line with predictions from animal models, the effect of testosterone on aPFC engagement decreased between middle and late adolescence, and shifted into an activational role by young adulthood-impeding neural control of emotions. This change in testosterone function was accompanied by increased testosterone-modulated amygdala reactivity. These findings qualify the testosterone-dependent maturation of the prefrontal-amygdala circuit supporting emotion control during the transition from middle adolescence into young adulthood.

Role of aldosterone and mineralocorticoid receptor (MR) in addiction: A scoping review

Preclinical and human studies suggest a role of aldosterone and mineralocorticoid receptor (MR) in addiction. This scoping review aimed to summarize (1) the relationship between alcohol and other substance use disorders (ASUDs) and dysfunctions of the aldosterone and MR, and (2) how pharmacological manipulations of MR may affect ASUD-related outcomes. Our search in four databases (MEDLINE, Embase, Web of Science, and Cochrane Library) indicated that most studies focused on the relationship between aldosterone, MR, and alcohol (n = 30), with the rest focused on opioids (n = 5), nicotine (n = 9), and other addictive substances (n = 9). Despite some inconsistencies, the overall results suggest peripheral and central dysregulations of aldosterone and MR in several species and that these dysregulations depended on the pattern of drug exposure and genetic factors. We conclude that MR antagonism may be a promising target in ASUD, yet future studies are warranted.

Sex differences in emotion- and reward-related neural responses predicting increases in substance use in adolescence

Adolescent substance use is a significant public health problem and there is a need for effective substance use preventions. To develop effective preventions, it is important to identify neurobiological risk factors that predict increases in substance use in adolescence and to understand potential sex differences in risk mechanisms. The present study used functional magnetic resonance imaging and hierarchical linear modeling to examine negative emotion- and reward-related neural responses in early adolescence predicting growth in substance use to middle adolescence in 81 youth, by sex. Adolescent neural responses to negative emotional stimuli and monetary reward receipt were assessed at age 12-14. Adolescents reported on substance use at age 12-14 and at 6 month, and 1, 2, and 3 year follow-ups. Adolescent neural responses did not predict initiation of substance use (yes/no), but, among users, neural responses predicted growth in substance use frequency. For girls, heightened right amygdala responses to negative emotional stimuli in early adolescence predicted growth in substance use frequency through middle adolescence. For boys, blunted left nucleus accumbens and bilateral ventromedial prefrontal cortex responses to monetary reward predicted growth in substance use frequency. Findings suggest different emotion and reward-related predictors of the development of substance use for adolescent girls versus boys.

Puberty and risky decision-making in male adolescents

Pubertal development is a potential trigger for increases in risk-taking behaviours during adolescence. Here, we sought to investigate the relationship between puberty and neural activation during risky decision-making in males using functional magnetic resonance imaging (fMRI). Forty-seven males aged 12.5-14.5 years completed an fMRI risk-taking task (BART) and reported their tendencies for risky decision-making using a self-report questionnaire. Puberty was assessed through self-reported pubertal status and salivary testosterone levels. Testosterone concentration, but not physical pubertal status, was positively correlated with self-reported risk-taking behaviour, while neither was correlated with BART performance. Across the whole sample, participants had greater activation of the bilateral nucleus accumbens and right caudate on trials when they made a successful risky decision compared to trials when they made a safe choice or when their risky decision was unsuccessful. There was a negative correlation between pubertal stage and brain activation during unsuccessful risky decision-making trials compared within unsuccessful control trials. Males at a lower stage of pubertal development showed increased activation in the left insula, right cingulate cortex, dorsomedial prefrontal cortex (dmPFC), right putamen and right orbitofrontal cortex (OFC) relative to more pubertally mature males during trials when they chose to take a risk and the balloon popped compared to when they watched the computer make an unsuccessful risky decision. Less pubertally mature males also showed greater activation in brain regions including the dmPFC, right temporal and frontal cortices, right OFC, right hippocampus and occipital cortex in unsuccessful risky trials compared to successful risky trials. These results suggest a puberty-related shift in neural activation within key brain regions when processing outcomes of risky decisions, which may reduce their sensitivity to negative feedback, and in turn contribute to increases in adolescent risk-taking behaviours.

Adolescents' Perceptions of Social Risk and Prosocial Tendencies: Developmental Change and Individual Differences

Many prosocial behaviors involve social risks such as speaking out against a popular opinion, bias, group norm, or authority. However, little is known about whether adolescents' prosocial tendencies develop over time with their perceptions of social risks. This accelerated longitudinal study used within-subject growth-curve analyses to test the link between prosocial tendencies and social risk perceptions, in a sample of adolescents who completed self-reports annually for three years (N = 893; M age = 12.30 years, 10 - 14 years at Wave 1, and 10 - 17 years across the full study period; 50% Girls, 33% White non-Latinx, 27% Latinx, 20% African American, 20% Mixed/Other Race). The association between social risk tolerance and prosocial tendencies changed significantly across adolescence, such that at for younger adolescents, more prosocial tendencies were associated with less social risk tolerance, whereas for relatively older adolescents, more prosocial tendencies were associated marginally with more social risk tolerance. Additional individual differences by empathy (but not sensation seeking) emerged. These findings suggest that prosocial development across adolescence may be associated with an underlying ability to tolerate social risks.

Adolescents Are More Likely to Help Others on Days They Take Risks and Crave Social Connections

This study examined how adolescents' risk-taking behaviors were related to their prosocial behaviors on a daily level and how this association differed depending on adolescents' daily and average levels of sensation seeking and social craving. Adolescents (N = 212; M_age  = 15 years) completed daily diaries for 14 days. Adolescents were more likely to engage in prosocial behavior on days when they also took risks, but only when they also felt high levels of social craving. The daily link between risk-taking and prosocial behavior did not vary based on daily or individual differences in sensation seeking. Results suggest that when adolescents feel highly motivated to connect with others, their risk-taking and prosocial tendencies co-occur on a daily basis.

A prospective investigation of youth alcohol experimentation and reward responsivity in the ABCD study

Rationale

Greater risk-taking behaviors, such as alcohol experimentation, are associated with different patterns of brain functioning in regions implicated in reward (nucleus accumbens, NA) and cognitive control (inferior frontal gyrus, IFG). These neural features have been observed in youth with greater risk-taking tendencies prior to substance use initiation, suggesting NA-IFG disruption may serve as an early marker for subsequent substance use disorders. Prospective studies are needed to determine if NA-IFG neural disruption predicts future substance use in school-age children, including those with minimal use of alcohol (e.g., sipping). The present large-sample prospective study sought to use machine learning to: (1) examine alcohol sipping at ages 9, 10 as a potential behavioral indicator of concurrent underlying altered neural responsivity to reward, and (2) determine if alcohol sipping and NA-IFG activation at ages 9, 10 can be used to predict which youth reported increased alcohol use at ages 11, 12. Additionally, low-level alcohol use and brain functioning at ages 9, 10 were examined as predictors of substance use and brain functioning at ages 11, 12.

Design and methods

This project used data from the baseline (Time 1) and two-year follow-up (Time 2) assessments of the Adolescent Brain Cognitive Development (ABCD) Study (Release 3.0). Support Vector Machine (SVM) learning determined if: (1) NA-IFG neural activity could correctly identify youth who reported alcohol sipping at Time 1 (n = 7409, mean age = 119.34 months, SD = 7.53; 50.27% female), and (2) NA-IFG and alcohol sipping frequency at Time 1 could correctly identify youth who reported drinking alcohol at Time 2 (n = 4000, mean age = 143.25 months, SD = 7.63; 47.53% female). Linear regression was also used to examine the relationship between alcohol sipping and NA-IFG activity at Time 1 and substance use and NA-IFG activity at Time 2. Data were also examined to characterize the environmental context in which youth first tried sips of alcohol (e.g., with or without parental permission, as part of a religious experience).

Results

Approximately 24% of the sample reported having tried sips of alcohol by ages 9, 10. On average, youth reported trying sips of alcohol 4.87 times (SD = 23.19) with age of first sip occurring at 7.36 years old (SD = 1.91). The first SVM model classified youth according to alcohol sipping status at Time 1 no better than chance with an accuracy of 0.35 (balanced accuracy = 0.52, sensitivity = 0.24, specificity = 0.80). The second SVM model classified youth according to alcohol drinking status at Time 2 with an accuracy of 0.76 (balanced accuracy = 0.56, sensitivity = 0.21, specificity = 0.91). Linear regression demonstrated that frequency of alcohol sipping at Time 1 predicted frequency of alcohol use at Time 2 (p < 0.001, adjusted R 2 = 0.075). Alcohol sipping at Time 1 was not linearly associated with NA or IFG activity at Time 2 (all ps > 0.05), and NA activity at Time 1 and Time 2 were not related (all ps > 0.05). Activity in the three subsections of the IFG at Time 1 predicted activity in those same regions at Time 2 (all ps < 0.02).

Conclusions and implications

Early sips of alcohol appear to predict alcohol use in early adolescence. Findings do not provide strong evidence for minimal early alcohol use (sipping) as a behavioral marker of underlying alterations in NA-IFG neural responsivity to reward. Improving our understanding of the neural and behavioral factors that indicate a greater propensity for future substance use is crucial for identifying at-risk youth and potential targets for preventative efforts.

Adolescent intermittent ethanol exposure produces Sex-Specific changes in BBB Permeability: A potential role for VEGFA

Binge drinking that typically begins during adolescence can have long-lasting neurobehavioral consequences, including alterations in the central and peripheral immune systems. Central and peripheral inflammation disrupts blood-brain barrier (BBB) integrity and exacerbates pathology in diseases commonly associated with disturbed BBB function. Thus, the goal of the present studies was to determine long-lasting effects of adolescent intermittent ethanol (AIE) on BBB integrity. For AIE, male and female Sprague Dawley rats were repeatedly exposed to ethanol (4 g/kg, intragastrically) or water during adolescence between postnatal day (P) 30 and P50. In adulthood (∼P75), rats were challenged with fluorescein isothiocyanate (FITC)-tagged Dextran of varying molecular weights (4, 20, & 70 kDa) for assessment of BBB permeability using gross tissue fluorometry (Experiment 1). Experiment 2 extended these effects using immunofluorescence, adding an adult ethanol-exposed group to test for a specific developmental vulnerability. Finally, as a first test of hypothesized mechanism, Experiment 3 examined the effect of AIE on Vascular Endothelial Growth Factor A (VEGFA) and its co-localization with pericytes (identified through expression of platelet derived growth factor receptor beta (PDGFRβ), a key regulatory cell embedded within the BBB. Male, but not female, rats with a history of AIE showed significantly increased dextran permeability in the nucleus accumbens (NAc), cingulate prefrontal cortex (cPFC), and amygdala (AMG). Similar increases in dextran were observed in the hippocampus (HPC) and ventral tegmental area (VTA) of male rats with a history of AIE or equivalent ethanol exposure during adulthood. No changes in BBB permeability were evident in females. When VEGFa expression was examined, male rats exposed to AIE were challenged with 3.5 g/kg ethanol (i.p.) or vehicle acutely in adulthood to assess long-lasting versus acute actions of ethanol. Adult rats with a history of AIE showed significantly fewer total cells expressing VEGFa in the AMG and dHPC following the acute ethanol challenge in adulthood. They also showed a significant reduction in the number of PDGFRβ positive cells that also expressed VEGFa signal. The anatomical distribution of these effects corresponded with increased BBB permeability after AIE (i.e., differential effects in the PVN, AMG, and dHPC). These studies demonstrated sex-specific effects of AIE, with males, but not females, demonstrating long-term increases in BBB permeability that correlated with changes in VEGFa and PDGFRβ protein, two factors known to influence BBB permeability.

Raging Hormones: Why Age-Based Etiological Conceptualizations of the Development of Antisocial Behavior Are Insufficient

Developmental science, particularly developmental neuroscience, has substantially influenced the modern legal system. However, this science has typically failed to consider the role of puberty and pubertal hormones on development when considering antisocial behavior. This review describes major theoretical positions on the developmental neuroscience of antisocial behavior and highlights where basic developmental neuroscience suggests that the role of puberty and pubertal hormones should be considered. The implications of the current state of the science with respect to developmental neuroscience is considered, particularly what is known in light of development beyond puberty. This review shows that development continues to an older age for many youth than the legal system typically acknowledges. The plasticity of the brain that this continued development implies has implications for the outcome of interventions in the legal system in ways that have not been explored. Future directions for both developmental scientists and legal professions are recommended.

Affect-Related Brain Activity and Adolescent Substance Use: A Systematic Review

Purpose of review

This review aims to summarize the research on brain activity during affective processing (i.e., reward, negative emotional stimuli, loss) and adolescent substance use (SU).

Recent findings

Most research revealed links between altered neural activity in midcingulo-insular, frontoparietal and other network regions and adolescent SU. Increased recruitment of midcingulo-insular regions-particularly the striatum-to positive affective stimuli (e.g., monetary reward) was most often associated with initiation and low-level use of substances, whereas decreased recruitment of these regions was most often associated with SUD and higher risk SU. In regards to negative affective stimuli, most research demonstrated increased recruitment of midcingulo-insular network regions. There is also evidence that these associations may be sex-specific.

Summary

Future research should employ longitudinal designs that assess affect-related brain activity prior to and following SU initiation and escalation. Moreover, examining sex as as moderating variable may help clarify if affective neural risk factors are sex-specific.

Risk-taking in humans and the medial orbitofrontal cortex reward system

Risk-taking differs between humans, and is associated with the personality measures of impulsivity and sensation-seeking. To analyse the brain systems involved, self-report risk-taking, resting state functional connectivity, and related behavioral measures were analyzed in 18,740 participants of both sexes from the UK Biobank. Functional connectivities of the medial orbitofrontal cortex, ventromedial prefrontal cortex (VMPFC), and the parahippocampal areas were significantly higher in the risk-taking group (p < 0.001, FDR corrected). The risk-taking measure was validated in that it was significantly associated with alcohol drinking amount (r = 0.08, p = 5.1×10^-28), cannabis use (r = 0.12, p = 6.0×10^-66), and anxious feelings (r = -0.12, p = 7.6×^-98). The functional connectivity findings were cross-validated in two independent datasets. The higher functional connectivity of the medial orbitofrontal cortex and VMPFC included higher connectivity with the anterior cingulate cortex, which provides a route for these reward-related regions to have a greater influence on action in risk-taking individuals. In conclusion, the medial orbitofrontal cortex, which is involved in reward value and pleasure, was found to be related to risk-taking, which is associated with impulsivity. An implication is that risk-taking is driven by specific orbitofrontal cortex reward systems, and is different for different rewards which are represented differently in the brains of different individuals. This is an advance in understanding the bases and mechanisms of risk-taking in humans, given that the orbitofrontal cortex, VMPFC and anterior cingulate cortex are highly developed in humans, and that risk-taking can be reported in humans.

Examining a new prosocial risk-taking scale in a longitudinal sample of ethnically diverse adolescents

INTRODUCTION

This longitudinal study designed and tested the validity of a new measure of prosocial risk taking - risks that individuals take in order to help others.

METHODS

The sample was racially and ethnically diverse adolescents in the rural Southeastern United States (N = 867; Mage = 12.82 years, 10-14 years at Wave 1; 50% Girls, 33% White non-Latinx, 27% Latinx, 20% Black, 20% Mixed/Other race/ethnicity). Adolescents completed self-report measures of the new prosocial risk-taking scale at baseline and one- and two-year follow-ups.

RESULTS

Confirmatory factor analysis demonstrated excellent model fit with a 6-item single factor score. Further, the scale demonstrated good test-retest reliability at one and two-year follow ups. The scale also demonstrated convergent validity, such that prosocial risk taking was positively correlated with prosocial tendencies, empathy, and sensation seeking, and negatively correlated with negative risk-taking behavior and risk tolerance. Finally, we found significant differences by race/ethnicity (but not by gender) in prosocial risk taking, which were not attributable to measurement invariance, and should be interpreted in the context of ongoing societal inequalities between youth.

CONCLUSIONS

The new Prosocial Risk-Taking Scale yielded reliable scores in our sample. It may be used in future research to investigate individual differences in adolescents' prosocial risk taking, developmental change in prosocial risk taking, and the significance of prosocial risk taking for adolescents' emotional and social adaptation.

Adolescent decision making: A decade in review

Research in the past decade has highlighted the nuances of adolescent decision making. In this review article, we summarize several themes evident in the field of developmental science including the redefinition of adolescence and the ways in which adolescent decision-making capabilities converge with or diverge from those of adults. While the decision-making process is similar for adolescents and adults in contexts that encourage deliberation and reflection, adolescents and adults differ in contexts which preclude deliberation vis-à-vis high emotional arousal. We also discuss the reconceptualization of adolescent behavior, including risk taking, as adaptive. That is, characteristics of adolescence, including impulsivity, the importance of peers, and novelty seeking, are normative, evolutionarily advantageous, and essential for positive development. While these features manifest in negative, health-compromising ways (e.g., risky driving and criminal behavior), they also foster growth and exploration. We conclude with a discussion of potential avenues for future research.

Neural activation to loss and reward among alcohol naive adolescents who later initiate alcohol use

Adolescent alcohol use is associated with adverse psychosocial outcomes, including an increased risk of alcohol use disorder in adulthood. It is therefore important to identify risk factors of alcohol initiation in adolescence. Research to date has shown that altered neural activation to reward is associated with alcohol use in adolescence; however, few studies have focused on neural activation to loss and alcohol use. The current study examined neural activation to loss and reward among 64 alcohol naive 12−14 year olds that did (n = 20) and did not initiate alcohol use by a three year follow-up period. Results showed that compared to adolescents that did not initiate alcohol use, adolescents that did initiate alcohol use by the three year follow-up period had increased activation to loss in the left striatum (i.e., putamen), right precuneus, and the brainstem/pons when they were alcohol naive at baseline. By contrast, alcohol initiation was not associated with neural activation to winning a reward. These results suggest that increased activation in brain regions implicated in salience, error detection/self-referential processing, and sensorimotor function, especially to negative outcomes, may represent an initial vulnerability factor for alcohol use in adolescence.

Evaluating the genetic effects of sex hormone traits on the development of mental traits: a polygenic score analysis and gene-environment-wide interaction study in UK Biobank cohort

OBJECTIVE

To evaluate the genetic effects of sex hormone traits on the development of mental traits in middle-aged adults.

METHODS

The SNPs associated with sex hormone traits were derived from a two-stage genome-wide association study (GWAS). Four sex hormone traits were selected in the current study, including sex hormone-binding globulin (SHBG), testosterone, bioavailable testosterone and estradiol. The polygenic risk score (PRS) of sex hormone traits were calculated from individual-level genotype data of the United Kingdom (UK) Biobank cohort. We then used logistic and linear regression models to assess the associations between individual PRS of sex hormone traits and the frequency of alcohol consumption, anxiety, intelligence and so on. Finally, gene-environment-wide interaction study (GEWIS) was performed to detect novel candidate genes interacting with the sex hormone traits on the development of fluid intelligence and the frequency of smoking and alcohol consumption by PLINK2.0.

RESULTS

We observed positive association between SHBG and the frequency of alcohol consumption (b = 0.0101, p = 3.84 × 10^-11) in middle-aged males and females. In addition, estradiol was positively associated with the frequency of alcohol consumption (b = 0.0128, p = 1.96 × 10^-8) in middle-aged males. Moreover, bioavailable testosterone was associated with the fluid intelligence (b = - 0.0136, p = 5.74 × 10^-5) in middle-aged females. Finally, GEWIS identified one significant loci, Tenascin R (TNR) (rs34633780, p = 3.45 × 10^-8) interacting with total testosterone for fluid intelligence.

CONCLUSION

Our study results support the genetic effects of sex hormone traits on the development of intelligence and the frequency of alcohol consumption in middle-aged adults in UK.

Neural and behavioral signatures of social evaluation and adaptation in childhood and adolescence: The Leiden consortium on individual development (L-CID)

The transition period between early childhood and late adolescence is characterized by pronounced changes in social competence, or the capacity for flexible social adaptation. Here, we propose that two processes, self-control and prosociality, are crucial for social adaptation following social evaluation. We present a neurobehavioral model showing commonalities in neural responses to experiences of social acceptance and rejection, and multiple pathways for responding to social context. The Leiden Consortium on Individual Development (L-CID) provides a comprehensive approach towards understanding the longitudinal developmental pathways of, and social enrichment effects on, social competence, taking into account potential differential effects of such enrichment. Using Neurosynth based brain maps we point towards the medial prefrontal cortex as an important region integrating social cognition, self-referential processing and self-control for learning to respond flexibly to changing social contexts. Based on their role in social evaluation processing, we suggest to examine medial prefrontal cortex connections with lateral prefrontal cortex and the ventral striatum as potential neural differential susceptibility markers, in addition to previously established markers of differential susceptibility.

Cortical and subcortical response to the anticipation of reward in high and average/low risk-taking adolescents

Since the first neurodevelopmental models that sought to explain the influx of risky behaviors during adolescence were proposed, there have been a number of revisions, variations and criticisms. Despite providing a strong multi-disciplinary heuristic to explain the development of risk behavior, extant models have not yet reliably isolated neural systems that underlie risk behaviors in adolescence. To address this gap, we screened 2017 adolescents from an ongoing longitudinal study that assessed 15-health risk behaviors, targeting 104 adolescents (Age Range: 17-to-21.4), characterized as high-or-average/low risk-taking. Participants completed the Monetary Incentive Delay (MID) fMRI task, examining reward anticipation to "big win" versus "neutral". We examined neural response variation associated with both baseline and longitudinal (multi-wave) risk classifications. Analyses included examination of a priori regions of interest (ROIs); and exploratory non-parametric, whole-brain analyses. Hypothesis-driven ROI analysis revealed no significant differences between high- and average/low-risk profiles using either baseline or multi-wave classification. Results of whole-brain analyses differed according to whether risk assessment was based on baseline or multi-wave data. Despite significant mean-level task activation, these results do not generalize prior neural substrates implicated in reward anticipation and adolescent risk-taking. Further, these data indicate that whole-brain differences may depend on how risk-behavior profiles are defined.

Hormonal responses in gambling versus alcohol abuse: A review of human studies

The endocrine system plays an essential role in communication between various organs of the body to maintain homeostasis. Both substance use disorders (SUDs) and non-substance abuse disrupt this system and lead to hormonal dysregulations. Here, we focus on the comparison between the function of the endocrine system in gambling disorders and alcohol addiction to understand the commonalities and differences in their neurobiological and psychological underpinnings. We review human research to compare findings on gambling addiction and alcohol dependence pertaining to the dynamic interplay between testosterone and cortisol. Understanding and classifying similarities in hormonal responses between behavioural addiction and SUDs may facilitate development of treatments and therapeutic interventions across different types of addictive disorders, while describing differences may shed light on therapeutic interventions for specific disorders. Although research on gambling addiction is in its infancy, such evaluation may still have a positive effect for addiction research, thereby stimulating discovery of "crossover" pharmacotherapies with benefits for both SUDs and nonsubstance addictions.

Neural reward related-reactions to monetar gains for self and charity are associated with donating behavior in adolescence

The aim of the current study was to examine neural signatures of gaining money for self and charity in adolescence. Participants (N = 160, aged 11–21) underwent functional magnetic resonance imaging-scanning while performing a zero-sum vicarious reward task in which they could either earn money for themselves at the expense of charity, for a self-chosen charity at the expense of themselves, or for both parties. Afterwards, they could donate money to charity, which we used as a behavioral index of giving. Gaining for self and for both parties resulted in activity in the ventral striatum (specifically in the NAcc), but not gaining for charity. Interestingly, striatal activity when gaining for charity was positively related to individual differences in donation behavior and perspective taking. Dorsal anterior cingulate cortex, insula and precentral gyrus were active when gaining only for self, and temporal-parietal junction when gaining only for charity, relative to gaining for both parties (i.e. under equity deviation). Taken together, these findings show that striatal activity during vicarious gaining for charity depends on levels of perspective taking and predicts future acts of giving to charity. These findings provide insight in the individual differences in the subjective value of prosocial outcomes.

Sex/gender differences in brain function and structure in alcohol use: A narrative review of neuroimaging findings over the last 10 years

Over the last 10 years, rates of alcohol use disorder (AUD) have increased in women by 84% relative to a 35% increase in men. Rates of alcohol use and high-risk drinking have also increased in women by 16% and 58% relative to a 7% and 16% increase in men, respectively, over the last decade. This robust increase in drinking among women highlights the critical need to identify the underlying neural mechanisms that may contribute to problematic alcohol consumption across sex/gender (SG), especially given that many neuroimaging studies are underpowered to detect main or interactive effects of SG on imaging outcomes. This narrative review aims to explore the recent neuroimaging literature on SG differences in brain function and structure as it pertains to alcohol across positron emission tomography, magnetic resonance imaging, and functional magnetic resonance imaging modalities in humans. Additional work using magnetic resonance spectroscopy, diffusion tensor imaging, and event-related potentials to examine SG differences in AUD will be covered. Overall, current research on the neuroimaging of AUD, alcohol consumption, or risk of AUD is limited, and findings are mixed regarding the effect of SG on neurochemical, structural, and functional mechanisms associated with AUD. We address SG disparities in the neuroimaging of AUD and propose a call to action to include women in brain imaging research. Future studies are crucial to our understanding of the neurobiological underpinnings of AUD across neural systems and the vulnerability for AUD among women and men.

Adolescent Personality Risk Factors for Tobacco Smoking and Alcohol Misuse in Adult Men

Background: Social identity theory proposes that people define themselves in terms of the social groups they belong to or aspire to belong to. Tobacco smoking and alcohol use in men have been hypothesized to be symbolic of adult male status. The current study examines whether adolescent personality characteristics linked to masculinity and nonconformity are associated with tobacco smoking and alcohol misuse in men. Methods: The analysis is based on the results of a cross-sectional study conducted in 2018 on a stratified, random sample of 703 adult male residents of Warsaw, Poland, with elementary- and secondary-school education. All survey data were collected through a paper-and-pencil questionnaire. A path model is employed to examine the direct and indirect effects of adolescent characteristics on tobacco smoking and alcohol consumption. Results: According to the path model, retrospective perceptions of self-reported character strength, rebellion against unjustified prohibitions and rules, ease in making decisions, willingness to differ from others, and interest in the opposite gender in adolescence had a significant direct effect on tobacco smoking in adolescence and a significant indirect effect on tobacco smoking in adulthood. The variables representing character strength, rebellion against unjustified prohibitions and rules, ease in making decisions, and interest in the opposite gender in adolescence also showed a significant direct effect on alcohol use in adolescence. Conclusion: Masculinity and nonconformity were related to addictive behaviors in men, which might have health policy implications. In this paper, associating traditional masculinity with health orientation in society is proposed as a possible preventive intervention.

Sex Differences in the Effect of Nucleus Accumbens Volume on Adolescent Drinking: The Mediating Role of Sensation Seeking in the NCANDA Sample

OBJECTIVE

In adolescence, sensation seeking is associated with earlier onset of alcohol use, which is a risk factor for a variety of negative consequences later in life. Individual differences in sensation seeking are related to brain function in the nucleus accumbens (NAcc), a brain region that undergoes considerable structural development during adolescence. Therefore, the goal of this study was to determine whether NAcc volume in alcohol-naive adolescents was associated with future sensation seeking and alcohol use and whether these associations differed by sex.

METHOD

High-resolution magnetic resonance imaging was used to measure NAcc volume at baseline in 514 alcohol-naive adolescents (50.2% female) from the National Consortium on Alcohol & Neurodevelopment in Adolescence study. Direct effects of NAcc volume on adolescent drinking 2 years after baseline, and indirect effects mediated through sensation seeking 1 year after baseline, were assessed.

RESULTS

An indirect effect of NAcc volume on subsequent drinking through sensation seeking was significant for males, but not females. This effect was driven by a positive association between NAcc volume and sensation seeking observed in male, but not female, participants. A direct effect of NAcc volume on subsequent alcohol use was detected in females, but not males. In females, no association between NAcc volume and sensation seeking was detected, but NAcc volume was positively associated with future alcohol use.

CONCLUSIONS

These findings suggest that delayed structural maturation of the NAcc may be a risk factor for alcohol use in adolescence; however, the mechanism by which the structure of the NAcc confers risk differs by sex.

Experience during adolescence shapes brain development: From synapses and networks to normal and pathological behavior

Adolescence is a period of dramatic neural reorganization creating a period of vulnerability and the possibility for the development of psychopathology. The maturation of various neural circuits during adolescence depends, to a large degree, on one's experiences both physical and psychosocial. This occurs through a process of plasticity which is the structural and functional adaptation of the nervous system in response to environmental demands, physiological changes and experiences. During adolescence, this adaptation proceeds upon a backdrop of structural and functional alterations imparted by genetic and epigenetic factors and experiences both prior to birth and during the postnatal period. Plasticity entails an altering of connections between neurons through long-term potentiation (LTP) (which alters synaptic efficiency), synaptogenesis, axonal sprouting, dendritic remodeling, neurogenesis and recruitment (Skaper et al., 2017). Although most empirical evidence for plasticity derives from studies of the sensory systems, recent studies have suggested that during adolescence, social, emotional, and cognitive experiences alter the structure and function of the networks subserving these domains of behavior. Each of these neural networks exhibits heightened vulnerability to experience-dependent plasticity during the sensitive periods which occur in different circuits and different brain regions at specific periods of development. This report will summarize some examples of adaptation which occur during adolescence and some evidence that the adolescent brain responds differently to stimuli compared to adults and children. This symposium, "Experience during adolescence shapes brain development: from synapses and networks to normal and pathological behavior" occurred during the Developmental Neurotoxicology Society/Teratology Society Annual Meeting in Clearwater Florida, June 2018. The sections will describe the maturation of the brain during adolescence as studied using imaging technologies, illustrate how plasticity shapes the structure of the brain using examples of pathological conditions such as Tourette's' syndrome and attention deficit hyperactivity disorder, and a review of the key molecular systems involved in this plasticity and how some commonly abused substances alter brain development. The role of stimulants used in the treatment of attention deficit hyperactivity disorder (ADHD) in the plasticity of the reward circuit is then described. Lastly, clinical data promoting an understanding of peer-influences on risky behavior in adolescents provides evidence for the complexity of the roles that peers play in decision making, a phenomenon different from that in the adult. Imaging studies have revealed that activation of the social network by the presence of peers at times of decision making is unique in the adolescent. Since normal brain development relies on experiences which alter the functional and structural connections between cells within circuits and networks to ultimately alter behavior, readers can be made aware of the myriad of ways normal developmental processes can be hijacked. The vulnerability of developing adolescent brain places the adolescent at risk for the development of a life time of abnormal behaviors and mental disorders.

Behavioral and Neural Pathways Supporting the Development of Prosocial and Risk-Taking Behavior Across Adolescence

This study tested the pathways supporting adolescent development of prosocial and rebellious behavior. Self‐report and structural brain development data were obtained in a three‐wave, longitudinal neuroimaging study (8–29 years, N = 210 at Wave 3). First, prosocial and rebellious behavior assessed at Wave 3 were positively correlated. Perspective taking and intention to comfort uniquely predicted prosocial behavior, whereas fun seeking (current levels and longitudinal changes) predicted both prosocial and rebellious behaviors. These changes were accompanied by developmental declines in nucleus accumbens and medial prefrontal cortex (MPFC) volumes, but only faster decline of MPFC (faster maturity) related to less rebellious behavior. These findings point toward a possible differential susceptibility marker, fun seeking, as a predictor of both prosocial and rebellious developmental outcomes.

Puberty and functional brain development in humans: Convergence in findings?

Although there is a long history of studying the influence of pubertal hormones on brain function/structure in animals, this research in human adolescents is young but burgeoning. Here, we provide a comprehensive review of findings from neuroimaging studies investigating the relation between pubertal and functional brain development in humans. We quantified the findings from this literature in which statistics required for standard meta-analyses are often not provided (i.e., effect size in fMRI studies). To do so, we assessed convergence in findings within content domains (reward, facial emotion, social information, cognitive processing) in terms of the locus and directionality (i.e., positive/negative) of effects. Face processing is the only domain with convergence in the locus of effects in the amygdala. Social information processing is the only domain with convergence of positive effects; however, these effects are not consistently present in any brain region. There is no convergence of effects in either the reward or cognitive processing domains. This limited convergence in findings across domains is not the result of null findings or even due to the variety of experimental paradigms researchers employ. Instead, there are critical theoretical, methodological, and analytical issues that must be addressed in order to move the field forward.

Effect of adolescent androgen manipulation on psychosis-like behaviour in adulthood in BDNF heterozygous and control mice

RATIONALE

Males are more prone to psychosis, schizophrenia and substance abuse and addiction in adolescence and early adulthood than females. However, the role of androgens during this developmental period is poorly understood.

OBJECTIVES

This study aimed to examine how androgens in adolescence influence psychosis-like behaviour in adulthood and whether brain-derived neurotrophic factor (BDNF) is a mediator of these developmental effects.

METHODS

Wild-type and BDNF heterozygous male mice were castrated at pre-pubescence and implanted with testosterone or dihydrotestosterone (DHT). In adulthood, we assessed amphetamine- and MK-801-induced hyperlocomotion as a model of psychosis-like behaviour. Western blot analysis was used to quantify levels of the dopamine transporter (DAT) and N-methyl-d-aspartate (NMDA) receptor subunits.

RESULTS

While castration itself had little effect on behaviour, adolescent testosterone, but not DHT, significantly reduced amphetamine-induced hyperlocomotion, whereas both testosterone and DHT reduced the effect of MK-801. These effects were similar in mice of either genotype. In wildtype mice, both testosterone and DHT treatment reduced DAT expression in the medial prefrontal cortex (mPFC) but these effects were absent in BDNF heterozygous mice. There were no effects on NMDA receptor subunit levels.

CONCLUSIONS

The differential effect of adolescent testosterone and DHT on amphetamine-induced hyperlocomotion in adulthood suggests involvement of conversion of testosterone to estrogen and subsequent modulation of dopaminergic signalling. In contrast, the similar effect of testosterone and DHT treatment on NMDA receptor-mediated hyperlocomotion indicates it is mediated by androgen receptors. The involvement of BDNF in these hormone effects remains to be elucidated. These results demonstrate that, during adolescence, androgens significantly influence key pathways related to various mental illnesses prevalent in adolescence.

Associations Between Adolescents' Social Re-orientation Toward Peers Over Caregivers and Neural Response to Teenage Faces

Adolescence is a period of intensive development in body, brain, and behavior. Potentiated by changes in hormones and neural response to social stimuli, teenagers undergo a process of social re-orientation away from their caregivers and toward expanding peer networks. The current study examines how relative relational closeness to peers (compared to parents) during adolescence is linked to neural response to the facial emotional expressions of other teenagers. Self-reported closeness with friends (same- and opposite-sex) and parents (mother and father), and neural response to facial stimuli during fMRI, were assessed in 8- to 19-year-old typically developing youth (n = 40, mean age = 13.90 years old, SD = 3.36; 25 female). Youth who reported greater relative closeness with peers than with parents showed decreased activation in the dorsolateral prefrontal cortex (dlPFC) during stimulus presentation, which may reflect lessened inhibitory control or regulatory response to peer-aged faces. Functional connectivity between the dlPFC and dorsal striatum was greatest in older youth who were closer to peers; in contrast, negative coupling between these regions was noted for both younger participants who were closer to peers and older participants who were closer to their parents. In addition, the association between relative closeness to peers and neural activation in regions of the social brain varied by emotion type and age. Results suggest that the re-orientation toward peers that occurs during adolescence is accompanied by changes in neural response to peer-aged social signals in social cognitive, prefrontal, and subcortical networks.

Developmental Maturation of the Precuneus as a Functional Core of the Default Mode Network

Efforts to map the functional architecture of the developing human brain have shown that connectivity between and within functional neural networks changes from childhood to adulthood. Although prior work has established that the adult precuneus distinctively modifies its connectivity during task versus rest states [Utevsky, A. V., Smith, D. V., & Huettel, S. A. Precuneus is a functional core of the default-mode network. Journal of Neuroscience, 34, 932-940, 2014], it remains unknown how these connectivity patterns emerge over development. Here, we use fMRI data collected at two longitudinal time points from over 250 participants between the ages of 8 and 26 years engaging in two cognitive tasks and a resting-state scan. By applying independent component analysis to both task and rest data, we identified three canonical networks of interest-the rest-based default mode network and the task-based left and right frontoparietal networks (LFPN and RFPN, respectively)-which we explored for developmental changes using dual regression analyses. We found systematic state-dependent functional connectivity in the precuneus, such that engaging in a task (compared with rest) resulted in greater precuneus-LFPN and precuneus-RFPN connectivity, whereas being at rest (compared with task) resulted in greater precuneus-default mode network connectivity. These cross-sectional results replicated across both tasks and at both developmental time points. Finally, we used longitudinal mixed models to show that the degree to which precuneus distinguishes between task and rest states increases with age, due to age-related increasing segregation between precuneus and LFPN at rest. Our results highlight the distinct role of the precuneus in tracking processing state, in a manner that is both present throughout and strengthened across development.

Hunting for What Works: Adolescents in Addiction Treatment

Although adolescents are developmentally distinct from adults, they often receive addiction treatment based on adult models. This is problematic because adolescents face significantly different conditions in addiction treatment, including distinct basic biological and neurodevelopmental stages, unique sociodevelopmental concerns, distinctive addiction trajectories, and, in turn, disparate treatment goals and outcomes. In sum, it can be difficult for even savvy clinicians to know how to approach addiction treatment with this important age group. In an effort to help clinicians and researchers consider substance use via a neurodevelopmental lens, we approached this review with 4 goals: (i) characterize the prevalence, and related health and safety implications of substance use within this age group; (ii) identify the nature of the adolescent brain, including characteristic features of this phase of neurodevelopment relevant to adolescent substance use treatment; (iii) provide an overview of current adolescent addiction interventions and avenues to improve clinical treatment and clinical research efforts for adolescents; and (iv) examine the intersection between the nature of the developing brain and adolescent substance use, and utilize that information to inform alternative routes and directions for substance use treatment in this critical age group. This review concludes by offering a novel neurodevelopmental model and framework to examine substance use interventions, along with a series of recommendations to optimize adolescent substance use treatment and clinical research.

Sex hormones in alcohol consumption: a systematic review of evidence

Sex hormones play an important role in establishing sex‐distinctive brain structural and functional variations that could contribute to the sex differences in alcohol consumption behavior. Here, we systematically reviewed articles that studied sex hormone impacts on alcohol consumption and alcohol use disorder (AUD). An extensive literature search conducted in MEDLINE, PubMed, Scopus and CINAHL databases identified 776 articles, which were then evaluated for pre‐specified criteria for relevance and quality assurance. A total of 50 articles, including 19 human studies and 31 animal studies, were selected for this review. Existing evidence supports the association of increased testosterone level and increased risk for alcohol use and AUD in males but results are inconclusive in females. In contrast, the evidence supports the association of increased estrogen level and increased alcohol use in females, with mixed findings reported in males. Much less is known about the impact of progestins on alcohol use and misuse in human subjects. Future observational and experimental studies conducted in both sexes with a comprehensive hormone panel are needed to elucidate the impact of the interplay between various sex hormone levels during various developmental stages on alcohol use‐related phenotypes and AUD.

Risk-taking, peer-influence and child maltreatment: a neurocognitive investigation

Maltreatment is associated with increased risk of a range of psychiatric disorders, many of which are characterized by altered risk-taking propensity. Currently, little is known about the neural correlates of risk-taking in children exposed to maltreatment, nor whether their risk-taking is atypically modulated by peer influence. Seventy-five 10- to 14-year-old children [maltreated (MT) group: N = 41; non-maltreated Group (NMT): N = 34] performed a Balloon Analogue Risk Task (BART), under three different peer influence conditions: while alone, while being observed by a peer and while being encouraged by a peer to take risks. The MT group engaged in less risk-taking irrespective of peer influence. There was no differential effect of peer influence on risk-taking behaviour across groups. At the neural level, the right anterior insula (rAI) exhibited altered risk sensitivity across conditions in the MT group. Across groups and conditions, rAI risk sensitivity was negatively associated with risk-taking and within the MT group greater rAI risk sensitivity was related to more anxiety symptoms. These findings suggest that children with a history of maltreatment show reduced risk-taking but typical responses to peer influence. Abnormal rAI functioning contributes to the pattern of reduced risk-taking and may predispose children exposed to maltreatment to develop future psychopathology.

Neurobiology of substance use in adolescents and potential therapeutic effects of exercise for prevention and treatment of substance use disorders

Substance use (e.g., alcohol, marijuana, opioids, cocaine., etc,) use often initiates during adolescence, a critical period of physiological and social development marked by an increase in risk-taking due, in part, to heightened motivation to obtain arousal from rewards. Substance use during adolescence has been associated with a greater risk of substance use disorders (SUD) in adulthood. Although use rates for most substances have remained relatively stable, the frequency of marijuana use and the perception that regular marijuana use is not harmful has increased in adolescents. Furthermore, the nonmedical use of opioids has increased, particularly in the South, Midwest, and rural low-income communities. Substance use in adolescence has been associated with adverse structural and functional brain changes and, may exacerbate the natural "imbalance" between frontal/regulatory and cortical-subcortical circuits, leading to further heightened impulsive and reward-driven behaviors. Exercise increases growth and brain-derived neurotrophic factors that stimulate endogenous dopaminergic systems that, in turn, enhance general plasticity, learning, and memory. Exercise may help to reinforce the "naïve" or underdeveloped connections between neurological reward and regulatory processes in adolescence from the "bottom up" and "offset" reward seeking from substances, while concomitantly improving cardiovascular health, as well as academic and social achievement. In this review, we provide an overview of the current state of substance use in adolescents and rationale for the utilization of exercise, particularly "assisted" exercise, which we have shown increases neural activity in cortical-subcortical regions and may modulate brain dopamine levels during adolescence, a unique window of heightened reward sensitivity and neural plasticity, for the prevention and adjunctive treatment of SUD.

Individual differences in risk-taking tendencies modulate the neural processing of risky and ambiguous decision-making in adolescence

Although many neuroimaging studies have investigated adolescent risk taking, few studies have dissociated between decision-making under risk (known probabilities) and ambiguity (unknown probabilities). Furthermore, which brain regions are sensitive to individual differences in task-related and self-reported risk taking remains elusive. We presented 198 adolescents (11-24 years, an age-range in which individual differences in risk taking are prominent) with an fMRI paradigm that separated decision-making (choosing to gamble or not) and reward outcome processing (gains, no gains) under risky and ambiguous conditions, and related this to task-related and self-reported risk taking. We observed distinct neural mechanisms underlying risky and ambiguous gambling, with risk more prominently associated with activation in parietal cortex, and ambiguity more prominently with dorsolateral prefrontal cortex (PFC), as well as medial PFC during outcome processing. Individual differences in task-related risk taking were positively associated with ventral striatum activation in the decision phase, specifically for risk, and negatively associated with insula and dorsomedial PFC activation, specifically for ambiguity. Moreover, dorsolateral PFC activation in the outcome phase seemed a prominent marker for individual differences in task-related risk taking under ambiguity as well as self-reported daily-life risk taking, in which greater risk taking was associated with reduced activation in dorsolateral PFC. Together, this study demonstrates the importance of considering multiple risk-taking measures, and contextual moderators, in understanding the neural mechanisms underlying adolescent risk taking.

Increased striatal activity in adolescence benefits learning

Adolescence is associated with enhanced striatal activity in response to rewards. This has been linked to increased risk-taking behavior and negative health outcomes. However, striatal activity is also important for learning, yet it is unknown whether heightened striatal responses in adolescence also benefit cognitive learning performance. In this longitudinal fMRI study (736 scans spanning 5 years in participants ages 8–29), we investigate whether adolescents show enhanced striatal activity during feedback learning, and whether this enhanced activity is associated with better learning performance. Here we report that neural activity indicating sensitivity to informative value of feedback peaks in late adolescence and occurs in dorsal caudate, ventral caudate, and nucleus accumbens. Increased activity in dorsal and ventral caudate predicts better current and future learning performance. This suggests that enhanced striatal activity in adolescents is adaptive for learning and may point to adolescence as a unique life phase for increased feedback-learning performance.

Adolescence is associated with negative behaviors that are related to enhanced reward-related striatal activity, but it is unclear whether this activity could also be beneficial. Here, authors report longitudinal data showing that enhanced striatal activity is related with increased learning ability.

Preliminary Evidence for Disrupted Nucleus Accumbens Reactivity and Connectivity to Reward in Binge Drinkers

AIMS

Dysfunctional brain reward circuitry, particularly in the nucleus accumbens (NAcc), has been proposed as a risk factor for alcohol use disorder (AUD). This risk factor may be evident in binge drinkers (BD), who are at high risk for developing AUD. We examined whole-brain and NAcc reactivity to reward in BD compared to non-binge drinkers (NBD), hypothesizing that groups would differ in their neural reactivity and connectivity.

METHODS

Healthy BD (N = 27) and NBD (N = 23)-none meeting AUD criteria-completed a reward-guessing game, the 'Doors' task, during functional magnetic resonance imaging. We conducted an exploratory whole-brain search for group differences, but given our a priori hypotheses, we also extracted activation from the NAcc to examine reactivity during reward (Win > Loss) and functional connectivity (FC) to the prefrontal cortex.

RESULTS

Compared to NBD, BD exhibited greater activation in both the right and left NAcc during reward relative to loss. Additionally, NBD drinkers exhibited positive FC between the NAcc and dorsal anterior cingulate (dACC) whereas the BD showed negative FC between these regions. Furthermore, less NAcc-dACC FC was related to more past month alcohol use.

CONCLUSIONS

Our results provide preliminary evidence that BD exhibit greater NAcc activation during reward receipt relative to loss. This is consistent with the broader AUD literature and suggests aberrant neural reactivity may precede disorder onset. In addition, BD exhibited less NAcc-dACC FC, perhaps reflecting deficient regulation of activation to rewards compared to losses. This profile of reward brain circuitry could represent neural correlates of vulnerability for AUD.

SHORT SUMMARY

Healthy binge drinkers, at risk for alcohol use disorder, exhibited greater nucleus accumbens activation during reward relative to loss. In addition, binge drinkers exhibited reduced connectivity between the nucleus accumbens and dorsal anterior cingulate, which was associated with more past month alcohol use.

Peers and parents: a comparison between neural activation when winning for friends and mothers in adolescence

Rewards reliably elicit ventral striatum activity. More recently studies have shown that vicarious rewards elicit similar activation. Ventral striatum responses to rewards for self peak during adolescence. However, it is currently not well understood how ventral striatum responses to vicarious rewards develop. In this study, we test this question using behavioral and fMRI data. A total of 233 participants aged 9–26 years old played a gambling game in the scanner in which they could win or lose money for themselves, their best friend and mother. Participants rated how close they felt to their friend and mother and how much they liked winning for them. These ratings were positively correlated. On the neural level males showed higher responses to winning for a friend, but there were no age differences. In contrast, there was a quadratic effect of age when winning for mother, showing heightened ventral striatum activity in mid-adolescence. Furthermore, there was an interaction between age and sex; for females responses to winning for friends become stronger with age relative to winning for mothers. In conclusion, this study provided evidence for elevated ventral striatum responses for mothers in mid-adolescence, and a shift in ventral striatum responses towards peers in girls.

Connecting brain responsivity and real-world risk taking: Strengths and limitations of current methodological approaches

In line with the goal of limiting health risk behaviors in adolescence, a growing literature investigates whether individual differences in functional brain responses can be related to vulnerability to engage in risky decision-making. We review this body of work, investigate when and in what way findings converge, and provide best practice recommendations. We identified 23 studies that examined individual differences in brain responsivity and adolescent risk taking. Findings varied widely in terms of the neural regions identified as relating to risky behavior. This heterogeneity is likely due to the abundance of approaches used to assess risk taking, and to the disparity of fMRI tasks. Indeed, brain-behavior correlations were typically found in regions showing a main effect of task. However, results from a test of publication bias suggested that region of interest approaches lacked evidential value. The findings suggest that neural factors differentiating riskier teens are not localized to a single region. Therefore, approaches that utilize data from the entire brain, particularly in predictive analyses, may yield more reliable and applicable results. We discuss several decision points that researchers should consider when designing a study, and emphasize the importance of precise research questions that move beyond a general desire to address adolescent risk taking.

Internal Consistency of Functional Magnetic Resonance Imaging and Electroencephalography Measures of Reward in Late Childhood and Early Adolescence

BACKGROUND

Abnormal neural response to reward is increasingly thought to function as a biological correlate of emerging psychopathology during adolescence. However, this view assumes such responses have good psychometric properties-especially internal consistency-an assumption that is rarely tested.

METHODS

Internal consistency (i.e., spilt-half reliability) was calculated for event-related potentials (ERPs) and Blood Oxygen Level Dependent (BOLD) responses to monetary gain and loss feedback from the same sample of 8-14 year-old females (n=177). Internal consistency for ERPs (i.e. feedback negativity) and BOLD responses within the ventral striatum and medial/lateral prefrontal cortex to gain, loss, difference scores (gain-loss), and residual scores (gain controlling for loss) were compared. Moderation analyses were conducted to investigate whether internal consistency differed by age.

RESULTS

ERP and BOLD responses to gain and loss feedback showed high internal consistency in all regions (Spearman Brown Coefficients (SB) ≥ 0.70). When considering difference and residual scores, however, responses showed lower internal consistency (SBs ≤ 0.50), with particularly low internal consistency for subtraction-based scores (SB ≤ 0.36). Age was not a significant moderator of split-half relationships, indicating similar internal consistency across late childhood to early adolescence.

CONCLUSIONS

Within the same subjects, high internal consistency was observed for both ERP and fMRI measures of response to gains and losses, which did not vary as a function of age. Moreover, excellent psychometric properties were evident even within the first half of the experiment. Difference scores were characterized by lower internal consistency, although regression-based approaches outperformed subtraction-based difference scores.

Exploring the role of testosterone in the cerebellum link to neuroticism: From adolescence to early adulthood

Previous research has found an association between a smaller cerebellar volume and higher levels of neuroticism. The steroid hormone testosterone reduces stress responses and the susceptibility to negative mood. Together with in vitro studies showing a positive effect of testosterone on cerebellar gray matter volumes, we set out to explore the role of testosterone in the relation between cerebellar gray matter and neuroticism. Structural magnetic resonance imaging scans were acquired, and indices of neurotic personality traits were assessed by administering the depression and anxiety scale of the revised NEO personality inventory and Gray's behavioural avoidance in one hundred and forty-nine healthy volunteers between 12 and 27 years of age. Results demonstrated an inverse relation between total brain corrected cerebellar volumes and neurotic personality traits in adolescents and young adults. In males, higher endogenous testosterone levels were associated with lower scores on neurotic personality traits and larger cerebellar gray matter volumes. No such relations were observed in the female participants. Analyses showed that testosterone significantly mediated the relation between male cerebellar gray matter and measures of neuroticism. Our findings on the interrelations between endogenous testosterone, neuroticism and cerebellar morphology provide a cerebellum-oriented framework for the susceptibility to experience negative emotions and mood in adolescence and early adulthood.

Adolescent neural response to reward is related to participant sex and task motivation

Risky decision making is prominent during adolescence, perhaps contributed to by heightened sensation seeking and ongoing maturation of reward and dopamine systems in the brain, which are, in part, modulated by sex hormones. In this study, we examined sex differences in the neural substrates of reward sensitivity during a risky decision-making task and hypothesized that compared with girls, boys would show heightened brain activation in reward-relevant regions, particularly the nucleus accumbens, during reward receipt. Further, we hypothesized that testosterone and estradiol levels would mediate this sex difference. Moreover, we predicted boys would make more risky choices on the task. While boys showed increased nucleus accumbens blood oxygen level-dependent (BOLD) response relative to girls, sex hormones did not mediate this effect. As predicted, boys made a higher percentage of risky decisions during the task. Interestingly, boys also self-reported more motivation to perform well and earn money on the task, while girls self-reported higher state anxiety prior to the scan session. Motivation to earn money partially mediated the effect of sex on nucleus accumbens activity during reward. Previous research shows that increased motivation and salience of reinforcers is linked with more robust striatal BOLD response, therefore psychosocial factors, in addition to sex, may play an important role in reward sensitivity. Elucidating neurobiological mechanisms that support adolescent sex differences in risky decision making has important implications for understanding individual differences that lead to advantageous and adverse behaviors that affect health outcomes.

Amygdala-orbitofrontal connectivity predicts alcohol use two years later: a longitudinal neuroimaging study on alcohol use in adolescence

This study tested the relation between cortical-subcortical functional connectivity and alcohol consumption in adolescents using an accelerated longitudinal design, as well as normative developmental patterns for these measures. Participants between ages 8 and 27 completed resting-state neuroimaging scans at two time points separated by two years (N = 274 at T1, N = 231 at T2). In addition, participants between ages 12 and 27 reported on recent and lifetime alcohol use (N = 193 at T1, N = 244 at T2). Resting-state connectivity analyses focused on amygdala-orbitofrontal connectivity given prior research linking reduced coupling between these regions to alcohol use. Mixed model analyses revealed that age had a cubic relationship with alcohol use, with little to no use in childhood, steep increases in adolescence and leveling off in adulthood. No age effects were found for amygdala-OFC connectivity. Prediction analyses showed that left amygdala-orbitofrontal connectivity at the first time point predicted recent and lifetime alcohol use two years later. There was no evidence for the reversed relation, suggesting that brain connectivity measures precede explorative risk-taking behavior in adolescence, possibly because decreased subcortical-frontal connectivity biases towards more explorative or risky behavior.

Association of testosterone and BDNF serum levels with craving during alcohol withdrawal

Preclinical and clinical studies show associations between testosterone and brain-derived neurotrophic growth factor (BDNF) serum levels. BDNF and testosterone have been independently reported to influence alcohol consumption. Therefore, we aimed to investigate a possible interplay of testosterone and BDNF contributing to alcohol dependence. Regarding possible interplay of testosterone and BDNF and the activity of the hypothalamic pituitary axis (HPA), we included cortisol serum levels in our research. We investigated testosterone and BDNF serum levels in a sample of 99 male alcohol-dependent patients during alcohol withdrawal (day 1, 7, and 14) and compared them to a healthy male control group (n = 17). The testosterone serum levels were significantly (p < 0.001) higher in the patients' group than in the control group and decreased significantly during alcohol withdrawal (p < 0.001). The decrease of testosterone serum levels during alcohol withdrawal (days 1-7) was significantly associated with the BDNF serum levels (day 1: p = 0.008). In a subgroup of patients showing high cortisol serum levels (putatively mirroring high HPA activity), we found a significant association of BDNF and testosterone as well as with alcohol craving measured by the Obsessive and Compulsive Drinking Scale (OCDS). Our data suggest a possible association of BDNF and testosterone serum levels, which may be relevant for the symptomatology of alcohol dependence. Further studies are needed to clarify our results.

Neurobiological signatures associated with alcohol and drug use in the human adolescent brain

Magnetic resonance (MR) techniques provide opportunities to non-invasively characterize neurobiological milestones of adolescent brain development. Juxtaposed to the critical finalization of brain development is initiation of alcohol and substance use, and increased frequency and quantity of use, patterns that can lead to abuse and addiction. This review provides a comprehensive overview of existing MR studies of adolescent alcohol and drug users. The most common alterations reported across substance used and MR modalities are in the frontal lobe (63% of published studies). This is not surprising, given that this is the last region to reach neurobiological adulthood. Comparatively, evidence is less consistent regarding alterations in regions that mature earlier (e.g., amygdala, hippocampus), however newer techniques now permit investigations beyond regional approaches that are uncovering network-level vulnerabilities. Regardless of whether neurobiological signatures exist prior to the initiation of use, this body of work provides important direction for ongoing prospective investigations of adolescent brain development, and the significant impact of alcohol and substance use on the brain during the second decade of life.