Neurobehavior disinhibition, parental substance use disorder, neighborhood quality and development of cannabis use disorder in boys

Prevalence and correlates of cannabis use disorder among Australians using cannabis products to treat a medical condition

INTRODUCTION

Prior research has examined the prevalence and correlates of cannabis use disorder (CUD) in people who use cannabis; however, these are poorly described for people using cannabis for medical reasons.

METHODS

Data came from a 2018 to 2019 online, anonymous, cross-sectional survey of Australians reporting using either illicit or licit cannabis for medical reasons within the past year. Included were questions on demographics, current and lifetime patterns of cannabis use, clinical conditions for which medical cannabis was used, and individual criteria for CUD and cannabis withdrawal syndrome. Bayesian Horseshoe logistic regression models were used to identify covariates associated with meeting CUD DSM-5 conditions for any-CUD (≥2/11 criteria) and moderate-severe-CUD (≥4/11).

RESULTS

A total of 905 participants were included in the analysis. The majority (98%) used illicit cannabis products. Criteria for any-CUD criteria were met by 290 (32.0%), and 117 (12.9%) met criteria for moderate-severe-CUD. Tolerance (21%) and withdrawal (35%) were the most commonly met criteria. Correlates with the strongest association with CUD were inhaled route of administration [odds ratio (OR) = 2.96, 95% credible interval 1.11, 7.06], frequency of cannabis use (OR = 1.24, 1.11-1.35), proportion of cannabis for medical reasons (OR = 0.83, 0.74, 0.94), frequency of tobacco use (OR = 1.10, 1.03, 1.17), age (OR = 0.75, 0.64, 0.90) and pain as main clinical indication (OR = 0.58, 0.36, 1.00).

DISCUSSION AND CONCLUSIONS

Prevalence of CUD in medical cannabis users appears comparable to 'recreational' users, with many similar correlates. CUD was associated with using cannabis to treat mental health rather than pain conditions and inhaled over other routes of administration.

Residential Greenspace and Urban Adolescent Substance Use: Exploring Interactive Effects with Peer Network Health, Sex, and Executive Function

While urban greenspace is increasingly recognized as important to mental health, its role in substance use is understudied. This exploratory study investigates the interaction of greenspace with peer network health, sex, and executive function (EF) in models of substance use among a sample of disadvantaged, urban youth. Adolescents and their parents were recruited from a hospital in the mid-Atlantic region of the U.S. Residential greenspace at the streetscape level was derived from analysis of Google Street View imagery. Logistic regression models were used to test the moderating effect of greenspace on the association between peer network health and substance use, as well as additional moderating effects of sex and EF. The significant negative association of peer network health with substance use occurred only among youth residing in high greenspace environments, a moderating effect which was stronger among youth with high EF deficit. The moderating effect of greenspace did not differ between girls and boys. Greenspace may play an important role in moderating peer influences on substance use among disadvantaged, urban adolescents, and such moderation may differ according to an individual's level of EF. This research provides evidence of differences in environmental susceptibility regarding contextual mechanisms of substance use among youth, and it informs the development of targeted substance use interventions that leverage social and environmental influences on adolescent substance use.

Developmental trajectory classes in psychological dysregulation predict later decision-making competence

Adolescence and emerging adulthood are developmental periods associated with increased risk taking, including alcohol and substance use and antisocial behaviors. Typical psychological growth from adolescence into early adulthood reflects increases in traits related to psychological regulation (e.g., greater emotional stability and less impulsivity), which are typically considered protective factors against risk behaviors. However, individuals may vary greatly in their development of these characteristics. This study examines the degree to which heterogeneity in developmental trajectories of psychological regulation are associated with later performance on decision-making skills battery. In this study, psychological regulation was assessed at age 10-12, with follow-up assessments at 14, 16, and 19 years. At age 19, we administered the Youth Decision-Making Competence (DMC; Parker & Fischhoff, 2005) measure. Correlational analyses revealed that lower psychological regulation, as early as age 10, was associated with lower DMC scores. A latent class growth mixture model yielded three distinct developmental trajectory classes of psychological dysregulation: (a) a Moderate-Stable group, a modal class that demonstrated stable and average regulative tendencies throughout adolescence, (b) a Low-Decreasing group, which demonstrated greater self-regulation throughout childhood, and a (c) High-Increasing group, which demonstrated low self-regulative tendencies (higher dysregulation) at age 10 that became increasingly dysregulated throughout adolescence. Individuals in the High-Increasing group demonstrated lower DMC performance than those in the Moderate-Stable and Low-Decreasing groups. Our findings also reinforce past work that indicates considerable individual differences in intra-individual change across adolescence, and that early patterns of psychological dysregulation development can impact later decision-making tendencies.

Integrating the study of personality and psychopathology in the context of gene-environment correlations across development

OBJECTIVE

A key principle of individual differences research is that biological and environmental factors jointly influence personality and psychopathology. Genes and environments interact to influence the emergence and stability of both normal and abnormal behavior (i.e., genetic predisposition, X, is exacerbated or buffered under environmental conditions, Y, or vice versa), including by shaping the neural circuits underpinning behavior. The interplay of genes and environments is also reflected in various ways in which they are correlated (i.e., rGE). That is, the same genetic factors that give rise to personality or psychopathology also shape that person's environment.

METHODS

In this review, we outline passive, evocative, and active rGE processes and review the findings of studies that have addressed rGE in relation to understanding individual differences in personality and psychopathology across development.

RESULTS

Throughout, we evaluate the question of whether it is possible, not only to differentiate the person from their problems, but also to differentiate the person from their problems and their environment.

CONCLUSIONS

We provide recommendations for future research to model rGE and better inform our ability to study personality and psychopathology, while separating the influence of the environment.

Characterizing psychiatric symptoms and neurocognitive functioning among substance-naïve early adolescents: Associations with sleep problems

AIM

Evidence consistently links psychiatric symptoms, reduced neurocognitive functioning (NCF) and sleep problems to the initiation of a wide range of risk behaviours. Less is known, however, about the associations between sleep problems with psychiatric symptoms and NCF among early adolescents yet to engage in substance use.

METHODS

The present study examined baseline data from an ongoing prospective study of 529 youth aged 10-12 years who completed a battery of instruments measuring symptom counts for four psychiatric disorders, performance on six tests of NCF and five types of sleep behaviour on week days. We used latent class analysis to classify the 473 substance-naïve youth into subtypes characterized by probabilistic patterns of psychiatric symptoms and poorer NCF.

RESULTS

Four subtypes emerged: normative (24% of the sample); nonspecific mental health symptoms (27%); lower neurocognitive function (24%) and comorbid psychiatric symptoms and lower neurocognitive function (25%). In a multivariable latent regression model, three or more sleep arousals per night, sleep phase of two or more hours and sleep latency of 20 minutes or more were significantly associated with the two classes having higher symptom counts. Lack of family support was significantly associated with the two classes having lower neurocognitive function and comorbid psychiatric symptoms.

CONCLUSIONS

The youth subtypes in this study provide an important baseline characterization to subsequently understand how these neuropsychiatric relationships may change when substance use and other risk behaviours develop during adolescence. Implications for preventing and treating sleep problems associated with psychiatric comorbidity and neurocognitive dysfunctions are discussed.

Risk for Substance Use Disorders in young adulthood: Associations with developmental experiences of homelessness, foster care, and adverse childhood experiences

BACKGROUND

Multiple developmental risk factors for Substance Use Disorders (SUDs) during young adulthood have been identified. In this investigation, we examined the impact of homelessness, foster care, and adverse childhood experiences (ACEs) prior to 12th grade on the development of three common SUDs during young adulthood-Alcohol Use Disorder (AUD), Tobacco Use Disorder (TUD) and Cannabis Use Disorder (CUD). Our hypothesis was that while both homelessness and ACEs are significant risk factors for young adult SUDs, foster care involvement might convey protection.

METHODS

Using nationally representative data from the National Longitudinal Study of Adolescent to Adult Health, measures of ACEs were derived from the CDC-Kaiser ACE study, and DSM-V SUD diagnoses were derived from items originally based on DSM-IV. SUD diagnoses were binned into "mild", "moderate", and "severe" groupings. Survey-based logistic models were used to estimate risks of SUDs while controlling for demographics.

RESULTS

The results suggest that the experience of homelessness prior to 12th grade in addition to ACEs were significantly associated with the development in young adulthood of the most severe forms of AUD and TUD and all severity levels of CUD. Foster care was not associated with either risk or protection from SUDs.

CONCLUSIONS

The experience of homelessness during development may be viewed as another detrimental ACE that is a risk factor for the most common SUDs in young adulthood. Given the magnitude of the current epidemic of homelessness in the U.S., these results should raise substantial concern.

Deconstructing the neurobiology of cannabis use disorder

There have been dramatic changes worldwide in the attitudes toward and consumption of recreational and medical cannabis. Cannabinoid receptors, which mediate the actions of cannabis, are abundantly expressed in brain regions known to mediate neural processes underlying reward, cognition, emotional regulation and stress responsivity relevant to addiction vulnerability. Despite debates regarding potential pathological consequences of cannabis use, cannabis use disorder is a clinical diagnosis with high prevalence in the general population and that often has its genesis in adolescence and in vulnerable individuals associated with psychiatric comorbidity, genetic and environmental factors. Integrated information from human and animal studies is beginning to expand insights regarding neurobiological systems associated with cannabis use disorder, which often share common neural characteristics with other substance use disorders, that could inform prevention and treatment strategies.

Investigating the causal effect of cannabis use on cognitive function with a quasi-experimental co-twin design

BACKGROUND

It is unclear whether cannabis use causes cognitive decline; several studies show an association between cannabis use and cognitive decline, but quasi-experimental twin studies have found little support for a causal effect. Here, we evaluate the association of cannabis use with general cognitive ability and executive functions (EFs) while controlling for genetic and shared environmental confounds in a longitudinal twin study.

METHODS

We first examined the phenotypic associations between cannabis initiation, frequency, and use disorder with cognitive abilities, while also controlling for pre-use general cognitive ability and other substance involvement. We tested the concurrent association between the cannabis use variables and cognitive abilities in late adolescence and young adulthood and the longitudinal association between cannabis use variables during adolescence and young adulthood cognitive abilities. Next, we used multilevel models to test whether these relations reflect between- and/or within-twin pair associations.

RESULTS

Phenotypically, cannabis use was related to poorer cognitive functioning, although most associations were negligible after accounting for other substance use. Nevertheless, there were few significant within-family twin-specific associations, except that age 17 cannabis frequency was associated with worse age 23 Common EF and general cognitive ability.

CONCLUSIONS

We found little support for a potential causal effect of cannabis use on cognition, consistent with previous twin studies. Results suggest that cannabis use may not cause decline in cognitive ability among a normative sample of cannabis users.

Robustness of Decision-Making Competence: Evidence from two measures and an 11-year longitudinal study

Decision-making competence is the ability to follow normative principles when making decisions. In a longitudinal analysis, we examine the robustness of decision-making competence over time, as measured by two batteries of paper-and-pencil tasks. Participants completed the youth version (Y-DMC) at age 19 and/or the adult version (A-DMC) eleven years later at age 30, as part of a larger longitudinal study. Both measures are comprised of tasks adapted from ones used in experimental studies of decision-making skills. Results supported the robustness of these measures and the usefulness of the construct. Response patterns for Y-DMC were similar to those observed with a smaller initial sample drawn from the same population. Response patterns for A-DMC were similar to those observed with an earlier community sample. Y-DMC and A-DMC were significantly correlated, for participants who completed both measures, 11 years apart, even after controlling for measures of cognitive ability. Nomological validity was observed in correlations of scores on both tests with measures of cognitive ability, cognitive style, and environmental factors with predicted relationships to decision-making competence, including household SES, neighborhood disadvantage, and paternal substance abuse. Higher Y-DMC and A-DMC scores were also associated with lower rates of potentially risky and antisocial behaviors, including adolescent delinquency, cannabis use, and early sexual behavior. Thus, the Y-DMC and A-DMC measures appear to capture a relatively stable, measurable construct that increases with supportive environmental factors and is associated with constructive behaviors.

Prevalence of Cannabis Use Disorder and Associated Factors among Cannabis Young Adult Users at Shashemene Town, Oromia Region, Ethiopia, 2016

Introduction

Cannabis users are at high risk of developing cannabis use disorder which is a problematic pattern of cannabis use leading to clinically significant impairment or distress.

Objective

To assess the magnitude of cannabis use disorder and associated factors among young adults using cannabis at Shashemene Town, Oromia Region, Ethiopia.

Methods

A cross-sectional study was conducted at Shashemene Town, from May to June 2016. Young adults aged 18–25 who use cannabis and are permanent residents of Shashemene were included in the study. Using single proportion formula, 423 participants were selected using exponential discriminative snow ball sampling.

Result

This study revealed that the magnitude of cannabis use disorder was 42.2%. The most contributing factors that remained to be statistically significant with cannabis use disorder were common mental disorder (AOR = 2.125, 95% CI: 1.218, 3.708), current cigarette smoking (AOR = 6.118, 95% CI: 2.13, 17.575), and current use of shisha (AOR = 4.313, 95% CI: 2.427, 7.664).

Conclusion

The magnitude of cannabis use disorder among young adults using cannabis was high.

Longitudinal Studies on the Etiology of Cannabis Use Disorder: A Review

PURPOSE OF REVIEW

This review summarizes the literature to date that has capitalized on the longitudinal research study framework in order to elucidate the etiology of cannabis use disorders (CUDs).

RECENT FINDINGS

The studies are mixed with respect to reliable predictors of CUD development. Of the studies outlined, the most consistently indicated risk factors for CUD development include: male sex, past cannabis and other substance use (especially tobacco), and the presence of pre/comorbid psychopathology (especially mood disorders). Social motives and peer involvement may also play a role in this transition. Many of these CUD risk factors appear to be distinct from other factors linked with overall cannabis use.

SUMMARY

CUD development is likely the product of interactions between biological, psychological, social, and environmental factors. However, many more well-planned and developmentally sensitive prospective studies are needed to identify specific and reliable risk factors for CUD development.

Marijuana Use and Dependence in Chilean Adolescents and Its Association with Family and Peer Marijuana Use

PURPOSE

The purpose of the study is to examine (1) whether family and peer marijuana use are independently related to adolescent marijuana use in Chile, (2) whether family and peer marijuana use are associated with adolescent marijuana dependence in adolescents using marijuana, and (3) whether the adolescent's age moderates the association between family or peer use and adolescent marijuana use and/or dependence.

METHOD

This study used data from the National Survey on Drug Use in the General Population in Chile (a cross-sectional observational study), which was conducted in 2008 and 2010 in 4413 adolescents aged 12-19. Adolescents answered questions about their past-year marijuana use and dependence (ICD-10 criteria) and the marijuana use of their family and peers. Logistic regressions were performed while controlling for confounders.

RESULTS

Adolescents who had a family member who used marijuana were five times more likely to use the drug. Adolescents with a close friend who used marijuana were eight times more likely to use marijuana. When adolescents were using marijuana, they were three times more likely to be dependent if they had a family member who used the drug. However, no significant relationship was found between peer use and dependence. No statistically significant interactions were found between family or peer use and age.

CONCLUSION

Family and peer marijuana use was independently associated with adolescent's past-year marijuana use; however, only family marijuana use was statistically associated with adolescent's marijuana dependence.

The impact of ADHD persistence, recent cannabis use, and age of regular cannabis use onset on subcortical volume and cortical thickness in young adults

BACKGROUND

Both Attention Deficit Hyperactivity Disorder (ADHD) and chronic cannabis (CAN) use have been associated with brain structural abnormalities, although little is known about the effects of both in young adults.

METHODS

Participants included: those with a childhood diagnosis of ADHD who were CAN users (ADHD_CAN; n=37) and non-users (NU) (ADHD_NU; n=44) and a local normative comparison group (LNCG) who did (LNCG_CAN; n=18) and did not (LNCG_NU; n=21) use CAN regularly. Multiple regressions and MANCOVAs were used to examine the independent and interactive effects of a childhood ADHD diagnosis and CAN group status and age of onset (CUO) on subcortical volumes and cortical thickness.

RESULTS

After controlling for age, gender, total brain volume, nicotine use, and past-year binge drinking, childhood ADHD diagnosis did not predict brain structure; however, persistence of ADHD was associated with smaller left precentral/postcentral cortical thickness. Compared to all non-users, CAN users had decreased cortical thickness in right hemisphere superior frontal sulcus, anterior cingulate, and isthmus of cingulate gyrus regions and left hemisphere superior frontal sulcus and precentral gyrus regions. Early cannabis use age of onset (CUO) in those with ADHD predicted greater right hemisphere superior frontal and postcentral cortical thickness.

DISCUSSION

Young adults with persistent ADHD demonstrated brain structure abnormalities in regions underlying motor control, working memory and inhibitory control. Further, CAN use was linked with abnormal brain structure in regions with high concentrations of cannabinoid receptors. Additional large-scale longitudinal studies are needed to clarify how substance use impacts neurodevelopment in youth with and without ADHD.

Association of exposure to neighborhood drug activity, neurobehavioral traits, and marijuana use among at-risk African American females

INTRODUCTION

Theories of relative deprivation suggest African Americans in disadvantaged communities are at increased risk for drug use. This increased risk may be due, in part, to exposure to drugs and drug subcultures. Given the significance of the prefrontal cortex (PFC) functioning in yielding behavior that is strategically guided rather than reactive to environmental demands, it is important to examine the relationship between PFC functioning, neighborhood drug activity and substance use among African Americans residing in high risk communities.

METHODS

A sample of 120 young adult African American females was recruited from high-risk neighborhoods. Each completed the modified version of the neighborhood environment scale, a neurobehavioral assessment designed to measure apathy, behavioral disinhibition and executive dysfunction, and provided a urine sample that was tested for the presence of psychoactive drugs.

RESULTS

Logistic regression analyses indicated that females with higher scores on behavioral disinhibition were 2.6 times more likely to test positive for marijuana (95%CI = 1.02, 6.57). Neither apathy nor executive dysfunction was related to marijuana use. No relationship emerged between neighborhood drug activity and marijuana use.

CONCLUSIONS

Among the neurobehavioral traits considered only behavioral disinhibition was associated with marijuana use, suggesting that different neurobehavioral domains may be uniquely related to marijuana use. For females living in high risk environments, the extent to which they are able to control impulses may provide some protection against marijuana use. Future studies focused on the moderating effects of behavioral disinhibition on the association of exposure to risk environments and marijuana use may prove beneficial. Further, the study adds to the small base of literature supporting the Frontal Systems Behavior Scale as a brief assessment to evaluate frontally-mediated neurobehavioral traits relevant to substance use. However, future studies aimed at examining the influence of neighborhood drug activity might benefit from more precise measures of exposure to neighborhood drug activity. More research to replicate and expand on the present findings is warranted.

Impulsivity: four ways five factors are not basic to addiction

Several impulsivity-related models have been applied to understanding the vulnerability to addiction. While there is a growing consensus that impulsivity is multifaceted, debate continues as to the precise number of facets and, more critically, which are most relevant to explaining the addiction-risk profile. In many ways, the current debate mirrors that which took place in the personality literature in the early 1990s (e.g., Eysenck's 'Big Three' versus Costa and McCrae's 'Big Five'). Indeed, many elements of this debate are relevant to the current discussion of the role of impulsivity in addictive behavior. Specifically, 1) the use of factor analysis as an atheoretical 'truth-grinding machine'; 2) whether additional facets add explanatory power over fewer; 3) the delineation of specific neurocognitive pathways from each facet to addictive behaviors, and; 4) the relative merit of 'top-down' versus 'bottom-up' approaches to the understanding of impulsivity. Ultimately, the utility of any model of impulsivity and addiction lies in its heuristic value and ability to integrate evidence from different levels of analysis. Here, we make the case that theoretically-driven, bottom-up models proposing two factors deliver the optimal balance of explanatory power, parsimony, and integration of evidence.

Impulsivity and substance use in young adulthood

BACKGROUND AND OBJECTIVES

Although the significant role of impulsive personality on substance use has been widely documented, distinct aspects of impulsivity and their relation to substance use during young adulthood have received scant attention. We sought to fill this research gap and explored impulsivity subtraits in relation to hazardous drinking and illicit substance use in young adulthood.

METHODS

The present study used cross-sectional survey data collected from a community sample of 257 young adults aged 18-25 (53% female). Data were primarily analyzed by three different types of regression models.

RESULTS

We found impulsivity to be more strongly associated with illicit substance use than hazardous drinking during young adulthood. Among the four impulsivity subtraits examined, lack of premeditation (p < .01) and sensation seeking (p < .05) were significantly related to illicit substance use in young adulthood.

CONCLUSIONS AND SIGNIFICANCE

These findings suggest that each impulsivity subtrait might play different roles in illicit substance use during young adulthood. For young adults, assessment of differential patterns of impulsive personality in individuals with substance use problems may have important implication for treatment strategies.

Considering Cannabis: The Effects of Regular Cannabis Use on Neurocognition in Adolescents and Young Adults

Thirty-six percent of high school seniors have used cannabis in the past year, and an alarming 6.5% smoked cannabis daily, up from 2.4% in 1993 (Johnston et al., 2013). Adolescents and emerging adults are undergoing significant neurodevelopment and animal studies suggest they may be particularly vulnerable to negative drug effects. In this review, we will provide a detailed overview of studies outlining the effects of regular (at least weekly) cannabis use on neurocognition, including studies outlining cognitive, structural and functional findings. We will also explore the public health impact of this research.

High and low neurobehavior disinhibition clusters within locales: implications for community efforts to prevent substance use disorder

BACKGROUND

Knowledge of where substance use and other such behavioral problems frequently occur has aided policing, public health, and urban planning strategies to reduce such behaviors. Identifying locales characterized by high childhood neurobehavioral disinhibition (ND), a strong predictor of substance use and consequent disorder (SUD), may likewise improve prevention efforts.

OBJECTIVES

The distribution of ND in 10-12-year olds was mapped to metropolitan Pittsburgh, PA, and tested for clustering within locales.

METHODS

The 738 participating families represented the population in terms of economic status, race, and population distribution. ND was measured using indicators of executive cognitive function, emotion regulation, and behavior control. Innovative geospatial analyzes statistically tested clustering of ND within locales while accounting for geographic barriers (large rivers, major highways), parental SUD severity, and neighborhood quality.

RESULTS

Clustering of youth with high and low ND occurred in specific locales. Accounting for geographic barriers better delineated where high ND is concentrated, areas which also tended to be characterized by greater parental SUD severity and poorer neighborhood quality.

CONCLUSIONS AND SIGNIFICANCE

Offering programs that have been demonstrated to improve inhibitory control in locales where youth have high ND on average may reduce youth risk for SUD and other problem behaviors. As demonstrated by the present results, geospatial analysis of youth risk factors, frequently used in community coalition strategies, may be improved with greater statistical and measurement rigor.

Modeling the association between sexual maturation, transmissible risk, and peer relationships during childhood and adolescence on development of substance use disorder in young adulthood

BACKGROUND

This prospective study investigated pubertal timing and transmissible risk in relation to affiliation with deviant peers on the development of substance use disorder (SUD).

METHOD

Participants were boys (N = 500) ascertained through proband fathers with (N = 250), and without (N = 250) DSM-III-R lifetime diagnosis of SUD who were prospectively tracked from age 10-12 to 22. Transmissible liability index (TLI), Tanner stage, peer delinquency, and substance use were measured at ages 10-12 and 16. SUD diagnosis during early adulthood was determined.

RESULTS

Structural equation modeling revealed two pathways in which transmissible risk and sexual maturation influenced development of SUD. In the first pathway, transmissible risk was correlated with and prospectively predicted affiliation with deviant peers and substance use presaging SUD. In the second pathway, advanced sexual maturation positively predicted affiliation with deviant peers and substance use, which in turn predicted SUD. However, transmissible risk was not associated with pubertal development.

CONCLUSION

These findings indicate that advanced sexual maturation and transmissible risk constitute unrelated facets of SUD liability; however, both factors bias development toward SUD via affiliation with deviant peers.

SCIENTIFIC SIGNIFICANCE

Youth with advanced sexual maturation and/or transmissible risk for SUD are at higher risk for developing SUD. Additional research is needed to determine if addressing these risk factors will contribute to advancements in SUD prevention.

Cortical activation deficits during facial emotion processing in youth at high risk for the development of substance use disorders

BACKGROUND

Recent longitudinal studies demonstrate that addiction risk may be influenced by a cognitive, affective and behavioral phenotype that emerges during childhood. Relatively little research has focused on the affective or emotional risk components of this high-risk phenotype, including the relevant neurobiology.

METHODS

Non-substance abusing youth (N=19; mean age=12.2) with externalizing psychopathology and paternal history of a substance use disorder and demographically matched healthy comparisons (N=18; mean age=11.9) were tested on a facial emotion matching task during functional MRI. This task involved matching faces by emotions (angry, anxious) or matching shape orientation.

RESULTS

High-risk youth exhibited increased medial prefrontal, precuneus and occipital cortex activation compared to the healthy comparison group during the face matching condition, relative to the control shape condition. The occipital activation correlated positively with parent-rated emotion regulation impairments in the high-risk group.

CONCLUSIONS

These findings suggest a preexisting abnormality in cortical activation in response to facial emotion matching in youth at high risk for the development of problem drug or alcohol use. These cortical deficits may underlie impaired affective processing and regulation, which in turn may contribute to escalating drug use in adolescence.

Relation among HPA and HPG neuroendocrine systems, transmissible risk and neighborhood quality on development of substance use disorder: results of a 10-year prospective study

BACKGROUND

Research has shown involvement of hormones of the hypothalamic pituitary adrenal (HPA) axis and hypothalamic pituitary gonadal (HPG) axis in the regulation of behaviors that contribute to SUD risk and its intergenerational transmission. Neighborhood environment has also been shown to relate to hormones of these two neuroendocrine systems and behaviors associated with SUD liability. Accordingly, it was hypothesized that (1) parental SUD severity and neighborhood quality correlate with activity of the HPG axis (testosterone level) and HPA axis (cortisol stability), and (2) transmissible risk during childhood mediates these hormone variables on development of SUD measured in adulthood.

METHODS

Transmissible risk for SUD measured by the transmissible liability index (TLI; Vanyukov et al., 2009) along with saliva cortisol and plasma testosterone were prospectively measured in boys at ages 10-12 and 16. Neighborhood quality was measured using a composite score encompassing indicators of residential instability and economic disadvantage. SUD was assessed at age 22.

RESULTS

Neither hormone variable cross-sectionally correlated with transmissible risk measured at ages 10-12 and 16. However, the TLI at age 10-12 predicted testosterone level and cortisol stability at age 16. Moreover, testosterone level, correlated with cortisol stability at age 16, predicted SUD at age 22.

CONCLUSION

HPA and HPG axes activity do not underlie variation in TLI, however, high transmissible risk in childhood predicts neuroendocrine system activity presaging development of SUD.

Dare to delay? The impacts of adolescent alcohol and marijuana use onset on cognition, brain structure, and function

Throughout the world, drug and alcohol use has a clear adolescent onset (Degenhardt et al., 2008). Alcohol continues to be the most popular drug among teens and emerging adults, with almost a third of 12th graders and 40% of college students reporting recent binge drinking (Johnston et al., 2009, 2010), and marijuana (MJ) is the second most popular drug in teens (Johnston et al., 2010). The initiation of drug use is consistent with an overall increase in risk-taking behaviors during adolescence that coincides with significant neurodevelopmental changes in both gray and white matter (Giedd et al., 1996a; Paus et al., 1999; Sowell et al., 1999, 2002, 2004; Gogtay et al., 2004; Barnea-Goraly et al., 2005; Lenroot and Giedd, 2006). Animal studies have suggested that compared to adults, adolescents may be particularly vulnerable to the neurotoxic effects of drugs, especially alcohol and MJ (see Schneider and Koch, 2003; Barron et al., 2005; Monti et al., 2005; Cha et al., 2006; Rubino et al., 2009; Spear, 2010). In this review, we will provide a detailed overview of studies that examined the impact of early adolescent onset of alcohol and MJ use on neurocognition (e.g., Ehrenreich et al., 1999; Wilson et al., 2000; Tapert et al., 2002a; Hartley et al., 2004; Fried et al., 2005; Townshend and Duka, 2005; Medina et al., 2007a; McQueeny et al., 2009; Gruber et al., 2011, 2012; Hanson et al., 2011; Lisdahl and Price, 2012), with a special emphasis on recent prospective longitudinal studies (e.g., White et al., 2011; Hicks et al., 2012; Meier et al., 2012). Finally, we will explore potential clinical and public health implications of these findings.

Neurobehavioral disinhibition predicts initiation of substance use in children with prenatal cocaine exposure

BACKGROUND

In previous work we (Fisher et al., 2011) examined the emergence of neurobehavioral disinhibition (ND) in adolescents with prenatal substance exposure. We computed ND factor scores at three age points (8/9, 11 and 13/14 years) and found that both prenatal substance exposure and early adversity predicted ND. The purpose of the current study was to determine the association between these ND scores and initiation of substance use between ages 8 and 16 in this cohort as early initiation of substance use has been related to later substance use disorders. Our hypothesis was that prenatal cocaine exposure predisposes the child to ND, which, in turn, is associated with initiation of substance use by age 16.

METHODS

We studied 386 cocaine exposed and 517 unexposed children followed since birth in a longitudinal study. Five dichotomous variables were computed based on the subject's report of substance use: alcohol only; tobacco only; marijuana only; illicit substances and any substance.

RESULTS

Cox proportional hazard regression showed that the 8/9 year ND score was related to initiation of alcohol, tobacco, illicit and any substance use but not marijuana use. The trajectory of ND across the three age periods was related to substance use initiation in all five substance use categories. Prenatal cocaine exposure, although initially related to tobacco, marijuana and illicit substance initiation, was no longer significant with ND scores in the models.

CONCLUSION

Prenatal drug exposure appears to be a risk pathway to ND, which by 8/9 years portends substance use initiation.

Increased marijuana use and gender predict poorer cognitive functioning in adolescents and emerging adults

This study sought to characterize neuropsychological functioning in MJ-using adolescents and emerging adults (ages 18-26) and to investigate whether gender moderated these effects. Data were collected from 59 teens and emerging adults including MJ users (n = 23, 56% female) and controls (n = 35, 50% female) aged 18-26 (M = 21 years). Exclusionary criteria included independent Axis I disorders (besides SUD), and medical and neurologic disorders. After controlling for reading ability, gender, subclinical depressive symptoms, body mass index, and alcohol and other drug use, increased MJ use was associated with slower psychomotor speed/sequencing ability (p < .01), less efficient sustained attention (p < .05), and increased cognitive inhibition errors (p < .03). Gender significantly moderated the effects of MJ on psychomotor speed/sequencing ability (p < .003) in that males had a more robust negative relationship. The current study demonstrated that MJ exposure was associated with poorer psychomotor speed, sustained attention and cognitive inhibition in a dose-dependent manner in young adults, findings that are consistent with other samples of adolescent MJ users. Male MJ users demonstrated greater cognitive slowing than females. Future studies need to examine the neural substrates underlying with these cognitive deficits and whether cognitive rehabilitation or exercise interventions may serve as a viable treatments of cognitive deficits in emerging adult MJ users.

Adolescent substance use groups: antecedent and concurrent personality differences in a longitudinal study

This study attempted to extend Shedler and Block's (1990) influential study, which found that adolescent drug experimenters had the healthiest personality functioning compared to abstainers and frequent users. Using a prospective design, we examined the relationship between antecedent and concurrent personality and age-18 substance use in a community sample of 1,298 twins (96% Caucasian, 49% male). Personality measures at ages 11 and 18 assessed positive emotionality (agentic and communal), negative emotionality, and constraint. Substance use groups-abstainers, experimenters, and problem users-were created at age 18. Age-18 substance use groups differed in age-11 and age-18 constraint such that problem users were lower than experimenters, who were lower than abstainers. Age-18 substance use groups did not differ in age-18 positive emotionality. However, abstainers were significantly lower than experimenters in communal positive emotionality, whereas female abstainers scored higher in agentic positive emotionality than female experimenters, who scored higher than female problem users. Experimenters were significantly lower in negative emotionality than problem users. Our findings are inconsistent with the notion that experimenters had the healthiest personality functioning and instead suggest different strengths and weaknesses for each group. Future studies should examine agentic and communal positive emotionality separately.

Developmental pathways to adolescent cannabis abuse and dependence: child maltreatment, emerging personality, and internalizing versus externalizing psychopathology

Child maltreatment is strongly associated with adolescent psychopathology and substance abuse and dependence. However, developmental processes unfolding from childhood into adolescence that delineate this trajectory are not well understood. The current study used path analysis in a structural equation modeling framework to examine multiple mediator models, including ego control, ego resiliency, and internalizing and externalizing symptoms to investigate this developmental process. Participants were 415 children, assessed across 3 waves of data, (i.e., at ages 7 to 9, 10 to 12, and 13 to 15). The sample included maltreated (n = 259) and nonmaltreated (n = 156) children; groups were comparable in sociodemographic characteristics. Findings support an transactional-ecological model by revealing a developmental sequence in which severity of early childhood maltreatment potentiates less adaptive childhood personality functioning, followed by externalizing problems in preadolescence, and ultimately adolescent cannabis abuse and dependence symptoms. A developmental pathway from child maltreatment to adolescent cannabis abuse and dependence symptoms via personality and preadolescent internalizing problems was not supported. Understanding developmental pathways by which maltreatment experiences increase risk for substance abuse and dependence symptoms in youth has far-reaching implications for the treatment and prevention of substance use disorders.

Could a continuous measure of individual transmissible risk be useful in clinical assessment of substance use disorder? Findings from the National Epidemiological Survey on Alcohol and Related Conditions

OBJECTIVE

Toward meeting the need for a measure of individual differences in substance use disorder (SUD) liability that is grounded in the multifactorial model of SUD transmission, this investigation tested to what degree transmissible SUD risk is better measured using the continuous Transmissible Liability Index (TLI) (young adult version) compared to alternative contemporary clinical methods.

METHOD

Data from 9535 18- to 30-year-olds in the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions, a U.S. representative sample, were used to compute TLI scores and test hypotheses. Other variables were SUDs of each DSM-IV drug class, clinical predictors of SUD treatment outcomes, treatment seeking and usage, age of onset of SUDs and substance use (SU), and eligibility for SUD clinical trials.

RESULTS

TLI scores account for variation in SUD risk over and above parental lifetime SUD, conduct and antisocial personality disorder criteria and frequency of SU. SUD risk increases two- to four-fold per standard deviation increment in TLI scores. The TLI is associated with SUD treatment seeking and usage, younger age of onset of SU and SUD, and exclusion from traditional clinical trials of SUD treatment.

CONCLUSIONS

The TLI can identify persons with high versus low transmissible SUD risk, worse prognosis of SUD recovery and to whom extant SUD clinical trials results may not generalize. Recreating TLI scores in extant datasets facilitates etiology and applied research on the full range of transmissible SUD risk in development, treatment and recovery without obtaining new samples.

Cannabis Exposure in an Omani Child: First case report from Oman

We report a confirmed case of cannabis exposure in an Omani female child with developmental delay. Cannabis exposure in children can lead to many consequences; for example, chronic use can result in developmental delay, abnormal behaviour, and hyperactivity while there is a risk of coma with acute exposure. It is important for clinicians to consider substance abuse as a differential diagnosis for similar presentations in paediatric patients, noting that children are at risk of cannabis exposure if their parents/caregivers are cannabis users.

Abnormal cerebellar morphometry in abstinent adolescent marijuana users

Functional neuroimaging data from adults have, in general, revealed frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use. The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following 1 month of monitored abstinence. Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning. Following 1 month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use.