Neuroimaging methods for adolescent substance use disorder prevention science

Neuroimaging in Adolescents: Post-Traumatic Stress Disorder and Risk for Substance Use Disorders

Trauma in childhood and adolescence has long-term negative consequences in brain development and behavior and increases the risk for psychiatric disorders. Among them, post-traumatic stress disorder (PTSD) during adolescence illustrates the connection between trauma and substance misuse, as adolescents may utilize substances to cope with PTSD. Drug misuse may in turn lead to neuroadaptations in learning processes that facilitate the consolidation of traumatic memories that perpetuate PTSD. This reflects, apart from common genetic and epigenetic modifications, overlapping neurocircuitry engagement triggered by stress and drug misuse that includes structural and functional changes in limbic brain regions and the salience, default-mode, and frontoparietal networks. Effective strategies to prevent PTSD are needed to limit the negative consequences associated with the later development of a substance use disorder (SUD). In this review, we will examine the link between PTSD and SUDs, along with the resulting effects on memory, focusing on the connection between the development of an SUD in individuals who struggled with PTSD in adolescence. Neuroimaging has emerged as a powerful tool to provide insight into the brain mechanisms underlying the connection of PTSD in adolescence and the development of SUDs.

Stress exposures, neurodevelopment and health measures in the ABCD study

The Adolescent Brain Cognitive Development (ABCD) Study, a large, longitudinal study of brain development and child health, is uniquely positioned to explore relationships among stress, neurodevelopment, and psychiatric symptomatology, including substance use and addiction. There is much we do not know about how adverse experiences affect the developing brain and cognitive, social, emotional, and academic outcomes. The data collected by the ABCD Study will allow the examination of the relationships among these variables in adolescence, including the effects of stressors (e.g., abuse, neglect, household challenges, parental substance use) on psychological adjustment and other stress responses. A comprehensive protocol that includes physical and mental health, substance use, culture and environment, neurocognitive assessments, biospecimen analyses, and structural and functional neuroimaging will provide opportunities for learning about the impacts of stressors on health and other outcomes in the context of adolescent development. This knowledge could lead to the development of interventions that reduce or even reverse the impacts of stressors.

Toward an integrative science of the developing human mind and brain: Focus on the developing cortex

Based on the Huttenlocher lecture, this article describes the need for a more integrative scientific paradigm for addressing important questions raised by key observations made over 2 decades ago. Among these are the early descriptions by Huttenlocher of variability in synaptic density in cortex of postmortem brains of children of different ages and the almost simultaneous reports of cortical volume reductions on MR imaging in children and adolescents. In spite of much progress in developmental neurobiology, developmental cognitive neuroscience, and behavioral and imaging genetics, we still do not know how these early observations relate to each other. It is argued that large scale, collaborative research programs are needed to establish the associations between behavioral differences among children and imaging biomarkers, and to link the latter to cellular changes in the developing brain. Examples of progress and challenges remaining are illustrated with data from the Pediatric Imaging, Neurocognition, and Genetics Project (PING).

Temperament disturbances measured in infancy progress to substance use disorder 20 years later

OBJECTIVE

This prospective study determined whether temperament before two years of age predicts transmissible risk for substance use disorder (SUD) up to a decade later and SUD outcome in adulthood.

METHOD

Boys between 10 and 12 years of age (N = 482) were tracked to age 22. The previously validated transmissible liability index (TLI) was administered at baseline, and temperament prior to two years of age was retrospectively rated. The Structured Clinical Interview for DSM-III-R (SCID) was administered to document presence/absence of SUD for parents at baseline and sons at age 22.

RESULTS

Path analysis revealed that number of parents with SUD predicted severity of temperament disturbance in their sons which in turn predicted TLI score at age 10-12, presaging SUD. Temperament before age two did not predict SUD at age 22. The association between number of SUD parents and transmissible risk was mediated by severity of temperament disturbance.

CONCLUSION

Temperament disturbance in early childhood, reflecting quality of behavioral and emotion regulation, comprise psychological antecedents of transmissible risk for SUD.

Reward-Modulated Response Inhibition, Cognitive Shifting, and the Orbital Frontal Cortex in Early Adolescence

Immaturities in cognitive shifting are associated with adolescent risk behaviors. The orbital frontal cortex (OFC) regulates reward processing and response inhibition. This study tested the relationship between cognitive shifting, OFC activity, and reward-modulated response inhibition in young adolescents. An fMRI antisaccade (AS) paradigm examined the effects of reward conditions on inhibitory response and OFC processing. A validated self-report inventory assessed cognitive shifting. Compared to neutral, reward trials showed better AS performance and increased OFC activation. Cognitive shifting positively associated with AS performance in reward and neutral trials. Poorer cognitive shifting predicted greater OFC activation. Results indicate lower OFC efficiency, as greater activation to achieve correct performance, underlies cognitive shifting problems. These neurocognitive impairments are relevant for understanding adolescent risk behaviors.

Earlier adolescent substance use onset predicts stronger connectivity between reward and cognitive control brain networks

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Adolescents self-reported substance use yearly from ages 10 to 16.

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Nucleus accumbens seed-based functional connectivity measured at age 16.

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Earlier use predicts stronger connectivity with right frontoparietal network.

Background

Early adolescent onset of substance use is a robust predictor of future substance use disorders. We examined the relation between age of substance use initiation and resting state functional connectivity (RSFC) of the core reward processing (nucleus accumbens; NAcc) to cognitive control (prefrontal cortex; PFC) brain networks.

Method

Adolescents in a longitudinal study of Mexican-origin youth reported their substance use annually from ages 10 to 16 years. At age 16, 69 adolescents participated in a resting state functional magnetic resonance imaging scan. Seed-based correlational analyses were conducted using regions of interest in bilateral NAcc.

Results

The earlier that adolescents initiated substance use, the stronger the connectivity between bilateral NAcc and right dorsolateral PFC, right dorsomedial PFC, right pre-supplementary motor area, right inferior parietal lobule, and left medial temporal gyrus.

Discussion

The regions that demonstrated significant positive linear relationships between the number of adolescent years using substances and connectivity with NAcc are nodes in the right frontoparietal network, which is central to cognitive control. The coupling of reward and cognitive control networks may be a mechanism through which earlier onset of substance use is related to brain function over time, a trajectory that may be implicated in subsequent substance use disorders.

A Hierarchical Factor Model of Executive Functions in Adolescents: Evidence of Gene-Environment Interplay

Executive functions (EF) are a complex set of neurodevelopmental, higher-ordered processes that are especially salient during adolescence. Disruptions to these processes are predictive of psychiatric problems in later adolescence and adulthood. The objectives of the current study were to characterize the latent structure of EF using bifactor analysis and to investigate the independent and interactive effects of genes and environments on EF during adolescence. Using a representative young adolescent sample, we tested the interaction of a polymorphism in the serotonin transporter gene (5-HTTLPR) and parental supervision for EF through hierarchical linear regression. To account for the possibility of a hierarchical factor structure for EF, a bifactor analysis was conducted on the eight subtests of the Delis-Kaplan Executive Functions System (D-KEFS). The bifactor analysis revealed the presence of a general EF construct and three EF subdomains (i.e., conceptual flexibility, inhibition, and fluency). A significant 5-HTTLPR by parental supervision interaction was found for conceptual flexibility, but not for general EF, fluency or inhibition. Specifically, youth with the L/L genotype had significantly lower conceptual flexibility scores compared to youth with S/S or S/L genotypes given low levels of parental supervision. Our findings indicate that adolescents with the L/L genotype were especially vulnerable to poor parental supervision on EF. This vulnerability may be amenable to preventive interventions.