Substance abuse risk in emerging adults associated with smaller frontal gray matter volumes and higher externalizing behaviors

Striatal brain volume linked to severity of substance use in high-risk incarcerated youth

Substance use disorders among juveniles are a major public health concern and are often intertwined with other psychosocial risk factors including antisocial behavior. Identifying etiological risks and mechanisms promoting substance use disorders remains a high priority for informing more focused interventions in high-risk populations. The present study examined brain gray matter structure in relation to substance use severity among n = 152 high-risk, incarcerated boys (aged 14-20). Substance use severity was positively associated with gray matter volume across several frontal/striatal brain regions including amygdala, pallidum, putamen, insula, and orbitofrontal cortex. Effects were apparent when using voxel-based-morphometric analysis, as well as in whole-brain, data-driven, network-based approaches (source-based morphometry). These findings support the hypothesis that elevated gray matter volume in striatal reward circuits may be an endogenous marker for vulnerability to severe substance use behaviors among youth.

Young adults' expectations for healthcare following institutional betrayal

Healthcare-related institutional betrayal has been used to examine how patients' previous negative healthcare experiences influence their current provider-level trust and future interactions with the healthcare system. However, healthcare-related institutional betrayal has rarely been considered among emerging independent users of the healthcare system: college students. Moreover, it is unknown whether healthcare-related institutional betrayal is associated with future healthcare expectations among this population. Using a trauma-informed framework, this study examined the relations among self-reported experiences of healthcare-related institutional betrayal, trust in healthcare providers, and subsequent expectations for healthcare among college students (n = 967). Analyses considered whether greater past healthcare-related institutional betrayal during one's worst healthcare experience predicts i) lower current trust in healthcare providers and ii) greater negative expectations for future healthcare above and beyond trauma symptoms and the perceived severity of participants' worst healthcare experiences. Sixty-nine percent of participants endorsed having experienced at least one act of institutional betrayal, the most common being the institution not taking proactive steps to prevent unpleasant healthcare experiences (28.5%). As predicted theoretically, greater experiences of institutional betrayal accounted for 16% of the variance in current trust in healthcare providers, even after accounting for trauma symptoms and the severity of the worst healthcare experience. Greater endorsement of institutional betrayal experiences were also significantly associated with negative expectations for future healthcare. Given the youthfulness of the sample, it is noteworthy that 41.4% of participants endorsed at least one negative expectation for future healthcare. Future research should examine how negative expectations are related to healthcare avoidance behaviors.

Prefrontal-Limbic Circuitry Is Associated With Reward Sensitivity in Nonhuman Primates

BACKGROUND

Abnormal reward sensitivity is a risk factor for psychiatric disorders, including eating disorders such as overeating and binge-eating disorder, but the brain structural mechanisms that underlie it are not completely understood. Here, we sought to investigate the relationship between multimodal whole-brain structural features and reward sensitivity in nonhuman primates.

METHODS

Reward sensitivity was evaluated through behavioral economic analysis in which monkeys (adult rhesus macaques; 7 female, 5 male) responded for sweetened condensed milk (10%, 30%, 56%), Gatorade, or water using an operant procedure in which the response requirement increased incrementally across sessions (i.e., fixed ratio 1, 3, 10). Animals were divided into high (n = 6) or low (n = 6) reward sensitivity groups based on essential value for 30% milk. Multimodal magnetic resonance imaging was used to measure gray matter volume and white matter microstructure. Brain structural features were compared between groups, and their correlations with reward sensitivity for various stimuli was investigated.

RESULTS

Animals in the high sensitivity group had greater dorsolateral prefrontal cortex, centromedial amygdaloid complex, and middle cingulate cortex volumes than animals in the low sensitivity group. Furthermore, compared with monkeys in the low sensitivity group, high sensitivity monkeys had lower fractional anisotropy in the left dorsal cingulate bundle connecting the centromedial amygdaloid complex and middle cingulate cortex to the dorsolateral prefrontal cortex, and in the left superior longitudinal fasciculus 1 connecting the middle cingulate cortex to the dorsolateral prefrontal cortex.

CONCLUSIONS

These results suggest that neuroanatomical variation in prefrontal-limbic circuitry is associated with reward sensitivity. These brain structural features may serve as predictive biomarkers for vulnerability to food-based and other reward-related disorders.

Sleep duration and brain MRI measures: Results from the SOL-INCA MRI study

INTRODUCTION

Sleep duration has been associated with dementia and stroke. Few studies have evaluated sleep pattern-related outcomes of brain disease in diverse Hispanics/Latinos.

METHODS

The SOL-INCA (Study of Latinos-Investigation of Neurocognitive Aging) magnetic resonance imaging (MRI) study recruited diverse Hispanics/Latinos (35-85 years) who underwent neuroimaging. The main exposure was self-reported sleep duration. Our main outcomes were total and regional brain volumes.

RESULTS

The final analytic sample included n = 2334 participants. Increased sleep was associated with smaller brain volume (βtotal_brain  = -0.05, p < 0.01) and consistently so in the 50+ subpopulation even after adjusting for mild cognitive impairment status. Sleeping >9 hours was associated with smaller gray (βcombined_gray  = -0.17, p < 0.05) and occipital matter volumes (βoccipital_gray  = -0.18, p < 0.05).

DISCUSSION

We found that longer sleep duration was associated with lower total brain and gray matter volume among diverse Hispanics/Latinos across sex and background. These results reinforce the importance of sleep on brain aging in this understudied population.

HIGHLIGHTS

Longer sleep was linked to smaller total brain and gray matter volumes. Longer sleep duration was linked to larger white matter hyperintensities (WMHs) and smaller hippocampal volume in an obstructive sleep apnea (OSA) risk group. These associations were consistent across sex and Hispanic/Latino heritage groups.

Brain Changes Linked to Cognitive Symptomatology in Homeless Youth

Youth impacted by homelessness experience diminished cognition due to a variety of reasons including mental health symptoms, alcohol and substance use, and adverse childhood experiences. However, the status of specific brain regions which could impact important cognitive functions in homeless youth remains unclear. In this pilot comparative and correlational study, a series of demographic, psychological, cognitive assessments, and brain magnetic resonance imaging were performed in 10 male youth experiencing homelessness and 9 age-matched healthy male controls (age range: 18-25 years). Participants experiencing homelessness had significantly decreased regional brain gray matter tissue in comparison to the controls. Moreover, there were strong inverse correlations between the brain regions classically associated with executive decision-making (prefrontal cortices), depression (insular lobes), and conflict resolution (anterior cingulate), and the level of the symptoms detected by their questionnaires.

The Genetically Informed Neurobiology of Addiction (GINA) model

Addictions are heritable and unfold dynamically across the lifespan. One prominent neurobiological theory proposes that substance-induced changes in neural circuitry promote the progression of addiction. Genome-wide association studies have begun to characterize the polygenic architecture undergirding addiction liability and revealed that genetic loci associated with risk can be divided into those associated with a general broad-spectrum liability to addiction and those associated with drug-specific addiction risk. In this Perspective, we integrate these genomic findings with our current understanding of the neurobiology of addiction to propose a new Genetically Informed Neurobiology of Addiction (GINA) model.

How Age and E-cigarette Use Status Interact to Influence E-cigarette Ad Perceptions

Background: The prevalence of e-cigarette use among young people remains high. Young people are susceptible to e-cigarette advertising, although potential heterogeneity in perceptions of e-cigarette ads with respect to age and e-cigarette use history remains unexplored. We aimed to assess differences in perceptions of e-cigarette ads and product use intention, by age and e-cigarette use status. Methods: Participants from an online convenience sample (N = 497, Mage=31.9) viewed two randomly selected e-cigarette ads and reported their perceptions of the ads and product use intention. We used mixed effects linear regression models to estimate associations between age group (18-20 years, 21-25 years, 26+ years), e-cigarette use status (never, former, and current use), and their interaction effects, on outcomes related to perceptions of ads and use intention. Models controlled for demographics and other tobacco use. Results: Current e-cigarette users (vs. never users) and participants who were 26+ years old (vs. 18-20 years old) had greater liking of the ads, perceived ad relevance, and perceived ad effectiveness. Among current e-cigarette users, participants who were 26+ years old (vs. 18-20 years old) had lower use intention. Conclusion: The effect of e-cigarette ad exposures on perceptions of the ad and use intention is heterogeneous with respect to age group and e-cigarette use history. While ads appealed more to adults who were 26+ years old across e-cigarette use groups, current e-cigarette users who were 18-20 years old demonstrated high use intention following ad exposure, suggesting a need for marketing interventions to mitigate continued e-cigarette use among young people.

Relationships between Personality Traits and Brain Gray Matter Are Different in Risky and Non-risky Drivers

Personality traits such as impulsivity or sensitivity to rewards and punishments have been associated with risky driving behavior, but it is still unclear how brain anatomy is related to these traits as a function of risky driving. In the present study, we explore the neuroanatomical basis of risky driving behavior and how the level of risk-taking influences the relationship between the traits of impulsivity and sensitivity to rewards and punishments and brain gray matter volume. One hundred forty-four participants with different risk-taking tendencies assessed by real-life driving situations underwent MRI. Personality traits were assessed with self-report measures. We observed that the total gray matter volume varied as a function of risky driving tendencies, with higher risk individuals showing lower gray matter volumes. Similar results were found for volumes of brain areas involved in the reward and cognitive control networks, such as the frontotemporal, parietal, limbic, and cerebellar cortices. We have also shown that sensitivity to reward and punishment and impulsivity are differentially related to gray matter volumes as a function of risky driving tendencies. Highly risky individuals show lower absolute correlations with gray matter volumes than less risk-prone individuals. Taken together, our results show that risky drivers differ in the brain structure of the areas involved in reward processing, cognitive control, and behavioral modulation, which may lead to dysfunctional decision-making and riskier driving behavior.

Alcohol use in emerging adults associated with lower rich-club connectivity and greater connectome network disorganization

BACKGROUND

Emerging adulthood is a critical neurodevelopmental stage, with alcohol use during this period consistently associated with brain abnormalities and damage in anatomical structure and white matter integrity. However, it is less clear how alcohol use is associated with the brain's structural organization (i.e., white matter connections between anatomical regions). Recent connectome research has focused on rich-club regions, a collection of highly-interconnected hubs that are critical in brain communication and global network organization and disproportionately vulnerable to insults.

METHODS

For the first time, we examined alcohol use associations with structural rich-club and connectome organization in emerging adults (N = 66).

RESULTS

Greater lifetime drinks and current monthly drinks were significantly associated with lower rich-club organization (r_s =-0.38, ps < 0.003) and lower rich-club connectivity (r_s <-0.34, ps < 0.007). Additionally, rich-club connectivity was significantly more negatively correlated with alcohol use than connectivity among non-rich-club regions (ps < 0.035). Examining overall structural organization, greater lifetime drinks and current monthly drinks were significantly associated with lower network density (i.e., lower network resilience; r_s <-0.36, ps = 0.004). Additionally, greater lifetime drinks and current monthly drinks were significantly associated with higher network segregation (i.e., network's tendency to divide into subnetworks; r_s >0.33, ps<0.008). Alcohol use was not significantly associated with network integration (i.e., network's efficiency in combining information across the brain; ps > 0.064).

CONCLUSIONS

Results provide novel evidence that alcohol use is associated with decreased rich-club connectivity and structural network disorganization. Given that both are critical in global brain communication, these results highlight the importance of examining alcohol use and brain relationships in emerging adulthood.

Alcohol and the Brain

Alcohol works on the brain to produce its desired effects, e.g., sociability and intoxication, and hence the brain is an important organ for exploring subsequent harms. These come in many different forms such as the consequences of damage during intoxication, e.g., from falls and fights, damage from withdrawal, damage from the toxicity of alcohol and its metabolites and altered brain structure and function with implications for behavioral processes such as craving and addiction. On top of that are peripheral factors that compound brain damage such as poor diet, vitamin deficiencies leading to Wernicke-Korsakoff syndrome. Prenatal alcohol exposure can also have a profound impact on brain development and lead to irremediable changes of fetal alcohol syndrome. This chapter briefly reviews aspects of these with a particular focus on recent brain imaging results. Cardiovascular effects of alcohol that lead to brain pathology are not covered as they are dealt with elsewhere in the volume.

Substance use behavior among Hispanic emerging adults in Los Angeles, California

This research examined illicit drug use and substance abuse disorders among Hispanic emerging adults using a two time-point study. Hypothesized predictors included concurrent use of different types of substances in adolescence and early adulthood (illicit drug use, binge alcohol use, and cigarette-smoking), along with the socialization context (family, peer, school, and other contextual factors) in adolescence. Overall, the findings showed that emerging adults who engaged in binge use of alcohol reported higher levels of illicit drug use and substance abuse disorders. Smoking cigarettes was associated with higher levels of illicit drug use in emerging adulthood, but not substance use disorders. Illicit drug use and binge alcohol use in adolescence were linked to higher levels of illicit drug use in emerging adulthood. Further, respondents who engaged in higher levels of illicit drug use, binge drinking, and smoking in adolescence were more likely to report higher levels of substance use disorders in early adulthood, signaling the importance of assessing adolescent drug use as a critical period for curbing long-term substance use-related impairment. Sibling alcohol use, college aspirations, and perceived discrimination during adolescence were also predictive of higher levels of substance use disorders in early adulthood. Higher academic achievement in adolescence, however, was associated with lower levels of illicit drug use in emerging adulthood. Lastly, males reported higher levels of illicit drug use and substance abuse disorders than females.

Subtypes of inhibitory and reward activation associated with substance use variation in adolescence: A latent profile analysis of brain imaging data

The present study identified subgroups based on inhibitory and reward activation, two key neural functions involved in risk-taking behavior, and then tested the extent to which subgroup differences varied by age, sex, behavioral and familial risk, and substance use. Participants were 145 young adults (18-21 years old; 40.0% female) from the Michigan Longitudinal Study. Latent profile analysis (LPA) was used to establish subgroups using task-based brain activations. Demographic and substance use differences between subgroups were then examined in logistic regression analyses. Whole-brain task activations during a functional magnetic resonance imaging go/no-go task and monetary incentive delay task were used to identify beta weights as input for LPA modeling. A four-class model showed the best fit with the data. Subgroups were categorized as: (1) low inhibitory activation/moderate reward activation (39.7%), (2) moderate inhibitory activation/low reward activation (22.7%), (3) moderate inhibitory activation/high reward activation (25.2%), and (4) high inhibitory activation/high reward activation (12.4%). Compared with the other subgroups, Class 2 was older, less likely to have parental alcohol use disorder, and had less alcohol use. Class 4 was the youngest and had greater marijuana use. Classes 1 and 3 did not differ significantly from the other subgroups. These findings demonstrate that LPA applied to brain activations can be used to identify distinct neural profiles that may explain heterogeneity in substance use outcomes and may inform more targeted substance use prevention and intervention efforts.

Alcohol use in young adults associated with cortical gyrification

BACKGROUND

Young adulthood has the highest rates of alcohol use and high-risk drinking behavior. This period is also a critical neurodevelopmental stage, with neural insults having a profound neurotoxic effect on the brain. Cortical gyrification is thought, in part, to reflect early brain maturation (e.g., hypogyrification in fetal alcohol syndrome). There is also evidence that cortical gyrification is sensitive to later-life events (e.g., fluctuations in malnutrition in young adults). However, no study has examined how alcohol use in young adulthood is associated with cortical gyrification.

METHODS

We examined the associations between cortical gyrification with lifetime alcohol use and past year hangover symptoms in young adults (N = 78).

RESULTS

Lifetime alcohol use was associated with hypogyria in multiple cortical regions (rs ≤ -.27, ps ≤ .0159; right orbitofrontal, right temporal pole, and left lateral occipital). Further, past year hangover symptoms were associated with hypogyria (rs ≤ -.27, ps ≤ .0034), overlapping with lifetime alcohol use (right orbitofrontal and left lateral occipital). Hangover symptoms were also uniquely associated with hypogyria of other cortical regions (rs ≤ -.30, ps ≤ .0002; right parahippocampal gyrus, left inferior temporal/parahippocampal gyrus and right anterior insula).

CONCLUSIONS

Thus, results suggest that young adulthood is a critical period for targeted prevention and intervention, especially for individuals exhibiting heavy alcohol consumption and high-risk drinking behavior.

The social historical roots of the concept of emerging adulthood and its impact on early adults

Adults between the ages of 18 and 25 live in an era of economic and social uncertainty. Outsourcing, automation, and decreased governmental social spending have led to lowered living standards for youth; they frequently change jobs, are more likely to live with other people and have few benefits attached to their employment thereby prohibiting them from thinking about their long-term goals. The bio-psychological sciences have responded by offering a new life stage that they call emerging adulthood (EA). The new characterization disempowers youth and naturalizes their new uncertainties as a biological condition. This article argues that the stage offers little new insight about the experiences of youth and limits individual empowerment. In addition, such a conceptualization of youth is indicative of the narrow range of possibilities for adulthood in a post-industrial world that offers few pathways to get there.

Cigarette smoking and gray matter brain volumes in middle age adults: the CARDIA Brain MRI sub-study

Cigarette smoking has been associated with dementia and dementia-related brain changes, notably gray matter (GM) volume atrophy. These associations are thought to reflect the co-morbidity of smoking and vascular, respiratory, and substance use/psychological conditions. However, the extent and localization of the smoking-GM relationship and the degree to which vascular, respiratory, and substance use/psychological factors influence this relationship remain unclear. In the Coronary Artery Risk Development in Young Adults CARDIA cohort (n = 698; 52% women; 40% black participants; age = 50.3 (SD = 3.5)), we examined the associations of smoking status with total GM volume and GM volume of brain regions linked to neurocognitive and addiction disorders. Linear regression models were used to adjust for vascular, respiratory, and substance use/psychological factors and to examine whether they modify the smoking-GM relationship. Compared to never-smokers, current smokers had smaller total GM volume (-8.86 cm³ (95%CI = -13.44, -4.29). Adjustment for substance use/psychological - but not vascular or respiratory - factors substantially attenuated this association (coefficients = -5.54 (95% CI = -10.32, -0.76); -8.33 (95% CI = -12.94, -3.72); -7.69 (95% CI = -6.95, -4.21), respectively). There was an interaction between smoking and alcohol use such that among alcohol non-users, smoking was not related to GM volumes and among alcohol users, those who currently smoked had -12 cm³ smaller total GM, specifically in the frontal and temporal lobes, amygdala, cingulate, and insula. Results suggest a large-magnitude association between smoking and smaller GM volume at middle age, accounting for vascular, respiratory, and substance use/psychological factors, and that the association was strongest in alcohol users. Regions suggested to be most vulnerable are those where cognition and addiction processes overlap.

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.

Research Review: What have we learned about adolescent substance use?

BACKGROUND

Adolescence is a critical biological, psychological, and social developmental stage involving heightened risk for substance use and associated adverse consequences. This review, synthesizing emerging findings on this complex topic, is intended to inform research and clinical care focused on adolescents.

METHODS

Literature searches were conducted using PubMed, yielding a cross-section of observational and interventional studies focused on adolescent substance use. Findings were organized and categorized to cover key areas of epidemiology, neurobiology, prevention, and treatment.

FINDINGS

Adolescent substance-related attitudes and use patterns have evolved over time, informed by adult and peer behaviors, public policy, media messaging, substance availability, and other variables. A number of risk and resiliency factors contribute to individual differences in substance use and related consequences. Advances in observational techniques have provided enhanced understanding of adolescent brain development and its implications for substance use. Prevention efforts have yielded mixed results, and while a number of adolescent-targeted evidence-based treatments for substance use disorders have been developed, effect sizes are generally modest, indicating the need for further research to enhance prevention and treatment outcomes.

CONCLUSIONS

Substance use in adolescence is heterogeneous, ranging from normative to pathological, and can lead to significant acute and long-term morbidity and mortality. Understanding risk and resiliency factors, underlying neurobiology, and optimal developmentally sensitive interventions is critical in addressing substance-associated problems in adolescence.

TLR4 Methylation Moderates the Relationship Between Alcohol Use Severity and Gray Matter Loss

OBJECTIVE

Alcohol use disorders (AUDs) are associated with decreased gray matter, and neuroinflammation is one mechanism through which alcohol may confer such damage, given that heavy alcohol use may promote neural damage via activation of toll-like receptor 4 (TLR4)-mediated inflammatory signaling cascades. We previously demonstrated that TLR4 is differentially methylated in AUD compared with control subjects, and the present study aims to extend this work by examining whether TLR4 methylation moderates the relationship between alcohol use and gray matter.

METHOD

We examined TLR4 methylation and gray matter thickness in a large sample (N = 707; 441 males) of adults (ages 18-56) reporting a range of AUD severity (mean Alcohol Use Disorders Identification Test score = 13.18; SD = 8.02). We used a series of ordinary least squares multiple regression equations to regress gray matter in four bilateral brain regions (precuneus, lateral orbitofrontal, inferior parietal, and superior temporal) on alcohol use, TLR4 methylation, and their interaction, controlling for demographic, psychological, and other substance use variables.

RESULTS

After we corrected for multiple tests, a significant Alcohol × TLR4 Methylation interaction emerged in the equations modeling left precuneus and right inferior parietal gray matter. Follow-up analyses examining the nature of these interactions demonstrated a significant negative association between alcohol and precuneus and inferior parietal gray matter in individuals with low TLR4 methylation, but no relationship between alcohol and gray matter in the high methylation group.

CONCLUSIONS

These findings suggest that TLR4 methylation may be protective against the damage conferred by alcohol on precuneus and inferior parietal gray matter, thereby implicating TLR4 for further investigation as a possible AUD treatment target.

Reduced Orbitofrontal Gray Matter Concentration as a Marker of Premorbid Childhood Trauma in Cocaine Use Disorder

Background: Childhood trauma affects neurodevelopment and promotes vulnerability to impaired constraint, depression, and addiction. Reduced gray matter concentration (GMC) in the mesocorticolimbic regions implicated in reward processing and cognitive control may be an underlying substrate, as documented separately in addiction and for childhood trauma. The purpose of this study was to understand the contribution of childhood maltreatment to GMC effects in individuals with cocaine use disorder.

Methods: Individuals with cocaine use disorder were partitioned into groups of low vs. high childhood trauma based on median split of the total score of the Childhood Trauma Questionnaire (CTQ; CUD-L, N = 23; CUD-H, N = 24) and compared with age, race, and gender matched healthy controls with low trauma (N = 29). GMC was obtained using voxel-based morphometry applied to T1-weighted MRI scans. Drug use, depression and constraint were assessed with standardized instruments.

Results: Whole-brain group comparisons showed reduced GMC in the right lateral orbitofrontal cortex (OFC) in CUD-H as compared with controls (cluster-level p_FWE-corr < 0.001) and CUD-L (cluster-level p_FWE-corr = 0.035); there were no significant differences between CUD-L and controls. A hierarchical regression analysis across both CUD groups revealed that childhood trauma, but not demographics and drug use, and beyond constraint and depression, accounted for 37.7% of the variance in the GMC in the right lateral OFC (p < 0.001).

Conclusions: Beyond other contributing factors, childhood trauma predicted GMC reductions in the OFC in individuals with cocaine use disorder. These findings underscore a link between premorbid environmental stress and morphological integrity of a brain region central for behaviors underlying drug addiction. These results further highlight the importance of accounting for childhood trauma, potentially as a factor predisposing to addiction, when examining and interpreting neural alterations in cocaine addicted individuals.

Adolescence and Drug Use Vulnerability: Findings from Neuroimaging

Adolescence is a period of vulnerability for developing substance use disorder. Recent neuropsychological and neuroimaging studies have elucidated underlying neural vulnerabilities that contribute to initiation of substance use during adolescence. Findings suggest poorer performance on tasks of inhibition and working memory, smaller brain volumes in reward and cognitive control regions, less brain activation during executive functioning tasks, and heightened reward responsivity are predictive of youth initiating substance use during adolescence. In youth who are family history positive (FHP) for substance use disorder, poorer executive functioning, smaller volume of limbic brain regions (e.g., amygdala), sex-specific patterns of hippocampal volume, and a positive association between nucleus accumbens volume and family history density have been reported. Further, reduced white matter integrity, altered brain response during inhibitory control, including both greater and less frontal lobe response, blunted emotional processing, and weaker neural connectivity have also been found in FHP youth. Thus, there is significant overlap among the neural precursors shown to be predictive of alcohol and substance use initiation during adolescence and those that distinguish FHP from youth without a family history of substance use disorder, suggesting common targets for prevention and intervention. Understanding these predictive factors helps identify at-risk youth for prevention efforts, as well as create interventions targeting cognitive weaknesses or brain regions involved in substance use initiation.

Alcohol and Drug Use and the Developing Brain

Adolescence is an important neurodevelopmental period marked by rapidly escalating rates of alcohol and drug use. Over the past decade, research has attempted to disentangle pre- and post-substance use effects on brain development by using sophisticated longitudinal designs. This review focuses on recent, prospective studies and addresses the following important questions: (1) what neuropsychological and neural features predate adolescent substance use, making youth more vulnerable to engage in heavy alcohol or drug use, and (2) how does heavy alcohol and drug use affect normal neural development and cognitive functioning? Findings suggest that pre-existing neural features that relate to increased substance use during adolescence include poorer neuropsychological functioning on tests of inhibition and working memory, smaller gray and white matter volume, changes in white matter integrity, and altered brain activation during inhibition, working memory, reward, and resting state. After substance use is initiated, alcohol and marijuana use are associated with poorer cognitive functioning on tests of verbal memory, visuospatial functioning, psychomotor speed, working memory, attention, cognitive control, and overall IQ. Heavy alcohol use during adolescence is related to accelerated decreases in gray matter and attenuated increases in white matter volume, as well as increased brain activation during tasks of inhibition and working memory, relative to controls. Larger longitudinal studies with more diverse samples are needed to better understand the interactive effects of alcohol, marijuana, and other substances, as well as the role of sex, co-occurring psychopathology, genetics, sleep, and age of initiation on substance use.

Selective Mapping of Psychopathy and Externalizing to Dissociable Circuits for Inhibitory Self-Control

Antisociality is commonly conceptualized as a unitary construct, but there is considerable evidence for multidimensionality. In particular, two partially dissociable symptom clusters - psychopathy and externalizing - have divergent associations to clinical and forensic outcomes and are linked to unique patterns executive dysfunction. Here, we used fMRI in a sample of incarcerated offenders to map these dimensions of antisocial behavior to brain circuits underlying two aspects of inhibitory self-control: interference suppression and response inhibition. We found that psychopathy and externalizing are characterized by unique and task-selective patterns of dysfunction. While higher levels of psychopathy predicted increased activity within a distributed fronto-parietal network for interference suppression, externalizing did not predict brain activity during attentional control. By contrast, each dimension had opposite associations to fronto-parietal activity during response inhibition. These findings provide neurobiological evidence supporting the fractionation of antisocial behavior, and identify dissociable mechanisms through which different facets predispose dysfunction and impairment.

Negative and interactive effects of sex, aging, and alcohol abuse on gray matter morphometry

Chronic alcohol use is associated with declines in gray matter (GM) volume, as is the normal aging process. Less apparent, however, is how the interaction between aging and heavy alcohol use affects changes in GM across the lifespan. There is some evidence that women are more vulnerable to the negative effects of alcohol use on GM than men. In the current study, we examined whether localized GM was related to measures of alcohol use disorder (e.g., AUDIT score) in a large sample (N = 436) of participants, ages 18-55 years, with a range of disease severity, using both voxel-based morphometry (VBM) and surface-based morphometry (SBM). We also explored whether GM associations with alcohol use disorder (AUD) severity are moderated by sex and age. Results showed significant negative associations between AUD severity and GM volume throughout temporal, parietal, frontal, and occipital lobes. Women showed more negative effects of alcohol use than men for cortical thickness in left orbitofrontal cortex, but evidence for increased vulnerability based on sex was limited overall. Similarly, a specific age by alcohol use interaction was observed for volume of right insula, but other regional or global interactions were not statistically supported. However, significant negative associations between heavy alcohol use and GM volumes were observed as early as 18-25 years. These findings support that alcohol has deleterious effects on global and regional GM above and beyond age, and, of particular importance, that regional associations emerge in early adulthood. Hum Brain Mapp 37:2276-2292, 2016. © 2016 Wiley Periodicals, Inc.

Reduced cortical thickness in right Heschl's gyrus associated with auditory verbal hallucinations severity in first-episode schizophrenia

BACKGROUND

Auditory verbal hallucinations (AVHs) represent one of the most intriguing phenomena in schizophrenia, however, brain abnormalities underlying AVHs remain unclear. The present study examined the association between cortical thickness and AVHs in first-episode schizophrenia.

METHOD

High-resolution MR images were obtained in 49 first-episode schizophrenia (FES) patients and 50 well-matched healthy controls (HCs). Among the FES patients, 18 suffered persistent AVHs ("auditory hallucination" AH group), and 31 never experienced AVHs ("no hallucination" NH group). The severity of AVHs was rated by the Auditory Hallucinations Rating Scale (AHRS). Cortical thickness differences among the three groups and their association with AVHs severity were examined.

RESULTS

Compared to both HCs and NH patients, AH patients showed lower cortical thickness in the right Heschl's gyrus. The degree of reduction in the cortical thickness was correlated with AVH severity in the AH patients.

CONCLUSIONS

Abnormalities of cortical thickness in the Heschl's gyrus may be a physiological factor underlying auditory verbal hallucinations in schizophrenia.

The somatic marker theory in the context of addiction: contributions to understanding development and maintenance

Recent theoretical accounts of addiction have acknowledged that addiction to substances and behaviors share inherent similarities (eg, insensitivity to future consequences and self-regulatory deficits). This recognition is corroborated by inquiries into the neurobiological correlates of addiction, which has indicated that different manifestations of addictive pathology share common neural mechanisms. This review of the literature will explore the feasibility of the somatic marker hypothesis as a unifying explanatory framework of the decision-making deficits that are believed to be involved in addiction development and maintenance. The somatic marker hypothesis provides a neuroanatomical and cognitive framework of decision making, which posits that decisional processes are biased toward long-term prospects by emotional marker signals engendered by a neuronal architecture comprising both cortical and subcortical circuits. Addicts display markedly impulsive and compulsive behavioral patterns that might be understood as manifestations of decision-making processes that fail to take into account the long-term consequences of actions. Evidence demonstrates that substance dependence, pathological gambling, and Internet addiction are characterized by structural and functional abnormalities in neural regions, as outlined by the somatic marker hypothesis. Furthermore, both substance dependents and behavioral addicts show similar impairments on a measure of decision making that is sensitive to somatic marker functioning. The decision-making deficits that characterize addiction might exist a priori to addiction development; however, they may be worsened by ingestion of substances with neurotoxic properties. It is concluded that the somatic marker model of addiction contributes a plausible account of the underlying neurobiology of decision-making deficits in addictive disorders that is supported by the current neuroimaging and behavioral evidence. Implications for future research are outlined.

Daily marijuana use is not associated with brain morphometric measures in adolescents or adults

Recent research has suggested that marijuana use is associated with volumetric and shape differences in subcortical structures, including the nucleus accumbens and amygdala, in a dose-dependent fashion. Replication of such results in well controlled studies is essential to clarify the effects of marijuana. To that end, this retrospective study examined brain morphology in a sample of adult daily marijuana users (n = 29) versus nonusers (n = 29) and a sample of adolescent daily users (n = 50) versus nonusers (n = 50). Groups were matched on a critical confounding variable, alcohol use, to a far greater degree than in previously published studies. We acquired high-resolution MRI scans, and investigated group differences in gray matter using voxel-based morphometry, surface-based morphometry, and shape analysis in structures suggested to be associated with marijuana use, as follows: the nucleus accumbens, amygdala, hippocampus, and cerebellum. No statistically significant differences were found between daily users and nonusers on volume or shape in the regions of interest. Effect sizes suggest that the failure to find differences was not due to a lack of statistical power, but rather was due to the lack of even a modest effect. In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures.

Cognitive failure and alexithymia and predicting high-risk behaviors of students with learning disabilities

Background:

One of the threatening health issues is prevalence of high-risk behaviors in various groups. Because of rapid social changes, it has been considered as of the most important problems of society by health organizations, administrative laws, and social policymakers.

Objectives:

The aim of this study was to determine the role of cognitive failure and alexithymia in predicting high-risk behaviors of students with learning disabilities.

Patients and Methods:

This was a correlational research including all 14-16 years old students during 2012-2013 school year in Arak, IR Iran. Eighty students with learning disabilities were sampled by simply random sampling. The data were collected by cognitive failures questionnaire, Toronto alexithymia scale, and high-risk behavior questionnaire.

Results:

The results showed that high-risk behaviors had significant positive correlations with difficulty identifying feelings (r = 0.321), difficulty describing feelings (r = 0.336), externally oriented thinking (r = 0.248), distractibility (0.292), memory distortion (r = 0.374), blunders (r = 0.335), and names amnesia (r = 0.275). Multiple regression analysis showed that cognitive failure and alexithymia predicted 32% of the total variance of high-risk behaviors.

Conclusions:

These findings demonstrated that cognitive failure and alexithymia had important roles in strengthening and appearance of high-risk behaviors in students with learning disabilities. Therefore, considering those problems, precautionary actions might be necessary.