Adolescent maturity and the brain: the promise and pitfalls of neuroscience research in adolescent health policy

The new imperative: reducing adolescent-related violence by building resilient adolescents

Involvement in violence is affected by a variety of risk factors and timing, duration, number of risks, and intensity of risk factors. The earlier the exposure to risk starts, the longer the exposure continues, the number of risks one is exposed to, and intensity of the risk factors experienced are all important. A child who is severely beaten, sexually abused, or both; one who grows up witnessing intimate partner or family violence; one who attends a failing school or is not involved in structured after-school activities; or one who lives in a violent neighborhood is at increased risk of becoming involved in violent behavior. The nature of the violence is worsened by the impact of shifting family structure and other risk factors such as alcohol and drugs. Adolescents who are exposed to positive parenting and supportive individuals, receive relevant education, are literate, possess life skills, and participate in structured, supervised activities become empowered young people who can resist violence.

Arrested development? Reconsidering dual-systems models of brain function in adolescence and disorders

The dual-systems model of a ventral affective system, whose reactivity confers risks and liabilities, and a prefrontal control system, whose regulatory capacities buffer against these vulnerabilities, is an intuitive account that pervades many fields in the cognitive neurosciences--especially in the study of populations that differ from neurotypical adults, such as adolescents or individuals with affective or impulse regulation disorders. However, recent evidence that is inconsistent with dual-systems models illustrates the complexity of developmental and clinical variations in brain function. Building new models to account for this complexity is critical to progress in these fields, and will be facilitated by research that emphasizes network-based approaches and maps relationships between structure and function, as well as brain and behavior, over time.

Adolescence: a foundation for future health

Adolescence is a life phase in which the opportunities for health are great and future patterns of adult health are established. Health in adolescence is the result of interactions between prenatal and early childhood development and the specific biological and social-role changes that accompany puberty, shaped by social determinants and risk and protective factors that affect the uptake of health-related behaviours. The shape of adolescence is rapidly changing-the age of onset of puberty is decreasing and the age at which mature social roles are achieved is rising. New understandings of the diverse and dynamic effects on adolescent health include insights into the effects of puberty and brain development, together with social media. A focus on adolescence is central to the success of many public health agendas, including the Millennium Development Goals aiming to reduce child and maternal mortality and HIV/AIDS, and the more recent emphases on mental health, injuries, and non-communicable diseases. Greater attention to adolescence is needed within each of these public health domains if global health targets are to be met. Strategies that place the adolescent years centre stage-rather than focusing only on specific health agendas-provide important opportunities to improve health, both in adolescence and later in life.

The role of child and adolescent development in the occurrence of agricultural injuries: an illustration using tractor-related injuries

Agricultural settings are dangerous, especially for children. This article focuses on child and adolescent development, and how development might influence children's safety in the occurrence of pediatric farm injuries. The authors focus especially on one of the most traumatic causes of pediatric farm injury, those associated with tractor operation. The roles of physical, perceptual, cognitive, and social development are reviewed and discussed, as are relevant sociocultural factors. Following review of developmental risks for child injury in agricultural settings, the authors present a case study of a fatal youth tractor injury and provide illustrations of the child development factors that may have contributed to the death. The authors conclude with a discussion of the implications of developmental aspects of pediatric agricultural injury for behaviorally oriented intervention strategies, including public policy.

Changes in histone acetylation in the prefrontal cortex of ethanol-exposed adolescent rats are associated with ethanol-induced place conditioning

Alcohol drinking during adolescence can induce long-lasting effects on the motivation to consume alcohol. Abnormal plasticity in reward-related processes might contribute to the vulnerability of adolescents to drug addiction. We have shown that binge-like ethanol treatment in adolescent rats induces alterations in the dopaminergic system and causes histone modifications in brain reward regions. Considering that histone acetylation regulates transcriptional activity and contributes to drug-induced alterations in gene expression and behavior, we addressed the hypothesis that ethanol is capable of inducing transcriptional changes by histone modifications in specific gene promoters in adolescent brain reward regions, and whether these events are associated with acquisition of place conditioning. After treating juvenile and adult rats with intermittent ethanol administration, we found that ethanol treatment upregulates histone acetyl transferase (HAT) activity in adolescent prefrontal cortex and increases histone (H3 or H4) acetylation and H3(K4) dimethylation in the promoter region of cFos, Cdk5 and FosB. Inhibition of histone deacetylase by sodium butyrate before ethanol injection enhances both up-regulation of HAT activity and histone acetylation of cFos, Cdk5 and FosB. Furthermore, co-administration of sodium butyrate with ethanol prolongs the extinction of conditioned place aversion and increased the reinstatement effects of ethanol in ethanol-treated adolescents, but not in ethanol-treated adult rats. These results indicate that ethanol exposure during adolescence induces chromatin remodeling, changes histone acetylation and methylation, and modify the effects of ethanol on place conditioning. They also suggest that epigenetic mechanisms might open up avenues to new treatments for binge drinking-induced drug addiction during adolescence.

Timing is everything: evidence for a role of corticolimbic endocannabinoids in modulating hypothalamic-pituitary-adrenal axis activity across developmental periods

Growing evidence suggests that the endocannabinoid system is vital to ensuring normative maturation of the brain into adulthood. Endocannabinoid signaling contributes to guiding pro-neurogenic processes in early life and the development of neurotransmitter systems. Moreover, there is extensive evidence that recruitment of the endocannabinoid system is crucial in the regulation of neuroendocrine responses to stress via the hypothalamic-pituitary-adrenal (HPA) axis, and contributes to subsequent psychopathological consequences associated with emotionality and anxiety. These stress-induced physiological and behavioural sequelae are regulated by neural structures within the corticolimbic circuit, including the amygdala, hypothalamus, hippocampus, and prefrontal cortex. Based on evidence demonstrating endocannabinoid system involvement in both development and stress-induced changes in HPA axis function, it is reasonable to suggest that endocannabinoid signaling is an important mediator of interactions between stress responsivity and maturational stage. In this review, we discuss the ontogeny of the endocannabinoid system in the central nervous system, clinical and rodent models demonstrating short- and long-term effects of stress exposure, regulation of HPA axis responsivity by endocannabinoid signaling, as well as pharmacological and stress models indicating involvement of the endocannabinoid system in early post-natal and adolescent development on stress reactivity of the HPA, the corticolimbic system, and behaviour.

The relationship between spirituality and religiosity on psychological outcomes in adolescents and emerging adults: a meta-analytic review

The present study used meta-analytic techniques to examine the association between spirituality and religiosity (S/R) and psychological outcomes in adolescents and emerging adults. The outcome measures of risk behavior, depression, well-being, self-esteem, and personality were examined with respect to the influence of S/R across 75 independent studies encompassing 66,273 adolescents and emerging adults extracted from electronic databases between 1990 and 2010. Results showed significant main effect sizes of S/R with several outcomes: risk behavior, -.17; depression, -.11; well-being, .16; self-esteem, .11; and the personality measures of Conscientiousness, .19; Agreeableness, .18; Openness, .14. Moderating effects were found for age, race, and type of S/R measure. Results show that S/R has a positive effect on psychological outcomes in adolescents and emerging adults. Possible explanations and implications of these results are discussed.

Executive functions in adolescents with spina bifida: relations with autonomy development and parental intrusiveness

The current study was part of a larger longitudinal investigation and examined the relation of parent-report and performance measures of executive functioning (EF) with measures of behavioral and emotional autonomy and parental intrusiveness in adolescents with and without spina bifida (SB; n=65 in a comparison sample and 61 in an SB sample; M age=14.55, SD=0.63). For both groups, higher levels of parent-reported EF problems predicted higher levels of observed child dependency and lower levels of teacher-reported intrinsic motivation. Higher scores on performance EF measures predicted lower levels of observed child dependency and observed maternal intrusiveness for both groups. In adolescents with SB only, higher performance EF scores predicted higher intrinsic motivation and emotional autonomy from both mother and father and predicted lower levels of observed paternal intrusiveness. While causal conclusions cannot be drawn, EFs appear to be closely related to autonomy development and parental intrusiveness, particularly for adolescents with SB. These results suggest that the inclusion of EF training in interventions targeting adolescents with SB may be beneficial for autonomy development.

Adolescent development and risk of injury: using developmental science to improve interventions

In adolescence, there is a complex interaction among physical, cognitive, and psychosocial developmental processes, culminating in greater risk-taking and novelty-seeking. Concurrently, adolescents face an increasingly demanding environment, which results in heightened vulnerability to injury. In this paper, we provide an overview of developmental considerations for adolescent injury interventions based on developmental science, including findings from behavioural neuroscience and psychology. We examine the role that typical developmental processes play in the way adolescents perceive and respond to risk and how this integrated body of developmental research adds to our understanding of how to do injury prevention with adolescents. We then highlight strategies to improve the translation of developmental research into adolescent injury prevention practice, calling on examples of existing interventions including graduated driver licensing.

The challenges and opportunities for transitional care research

The provision of healthcare for young people with solid organ transplants as they move into adult-centered services has received increasing attention over recent years particularly as non-adherence and graft loss increase after transfer. Despite medical advances and that transitional care is now well established on national and international health agendas, progress in the research arena has unfortunately been slow. The aims of this paper are to consider why this is and discuss the particular challenges facing clinical researchers working within the area.

Adolescents, adults and rewards: comparing motivational neurocircuitry recruitment using fMRI

BACKGROUND

Adolescent risk-taking, including behaviors resulting in injury or death, has been attributed in part to maturational differences in mesolimbic incentive-motivational neurocircuitry, including ostensible oversensitivity of the nucleus accumbens (NAcc) to rewards.

METHODOLOGY/PRINCIPAL FINDINGS

To test whether adolescents showed increased NAcc activation by cues for rewards, or by delivery of rewards, we scanned 24 adolescents (age 12-17) and 24 adults age (22-42) with functional magnetic resonance imaging while they performed a monetary incentive delay (MID) task. The MID task was configured to temporally disentangle potential reward or potential loss anticipation-related brain signal from reward or loss notification-related signal. Subjects saw cues signaling opportunities to win or avoid losing $0, $.50, or $5 for responding quickly to a subsequent target. Subjects then viewed feedback of their trial success after a variable interval from cue presentation of between 6 to 17 s. Adolescents showed reduced NAcc recruitment by reward-predictive cues compared to adult controls in a linear contrast with non-incentive cues, and in a volume-of-interest analysis of signal change in the NAcc. In contrast, adolescents showed little difference in striatal and frontocortical responsiveness to reward deliveries compared to adults.

CONCLUSIONS/SIGNIFICANCE

In light of divergent developmental difference findings between neuroimaging incentive paradigms (as well as at different stages within the same task), these data suggest that maturational differences in incentive-motivational neurocircuitry: 1) may be sensitive to nuances of incentive tasks or stimuli, such as behavioral or learning contingencies, and 2) may be specific to the component of the instrumental behavior (such as anticipation versus notification).

Staging perspectives in neurodevelopmental aspects of neuropsychiatry: agents, phases and ages at expression

Neurodevelopmental risk factors have assumed a critical role in prevailing notions concerning the etiopathogenesis of neuropsychiatric disorders. Staging, diagnostic elements at which phase of disease is determined, provides a means of conceptualizing the degree and extent of factors affecting brain development trajectories, but is concurrently specified through the particular interactions of genes and environment unique to each individual case. For present purposes, staging perspectives in neurodevelopmental aspects of the disease processes are considered from conditions giving rise to neurodevelopmental staging in affective states, adolescence, dopamine disease states, and autism spectrum disorders. Three major aspects influencing the eventual course of individual developmental trajectories appear to possess an essential determinant influence upon outcome: (i) the type of agent that interferes with brain development, whether chemical, immune system activating or absent (anoxia/hypoxia), (ii) the phase of brain development at which the agent exerts disruption, whether prenatal, postnatal, or adolescent, and (iii) the age of expression of structural and functional abnormalities. Clinical staging may be assumed at any or each developmental phase. The present perspective offers both a challenge to bring further order to diagnosis, intervention, and prognosis and a statement regarding the extreme complexities and interwoven intricacies of epigenetic factors, biomarkers, and neurobehavioral entities that aggravate currents notions of the neuropsychiatric disorders.

Neuromaturation and Adolescent Risk Taking: Why Development Is Not Determinism

In the January 2009 issue of this journal, Males argues that adolescent brain science perpetuates the “myth of adolescent risk taking.” He contends that those who study adolescent neuromaturation are biological determinists who ignore the profound social and environmental forces that influence adolescent behavior to further their own agendas. Males mischaracterizes developmental research and misinterprets public health data. This article analyzes his argument and provides a response based on the evidence. There is significant cross-species evidence that adolescence serves an important developmental function on the road to full maturation and is not merely an oppressive social construction. Research on neuromaturation can help elucidate both the vulnerabilities and tremendous potential of the adolescent brain. It also provides the opportunity to examine the role of social environments in shaping developmental processes and to explore how reasoned understandings of adolescent brain and biological development are being used to inform interventions that scaffold adolescent vulnerabilities.