A longitudinal daily diary method was employed to examine the implications of family assistance for the academic achievement of 563 adolescents (53% female) from Mexican (n = 217), Chinese (n =  206), and European (n = 140) backgrounds during the high school years (mean age 14.9 years in 9th grade to 17.8 years in 12th grade). Although changes in family assistance time within individual adolescents were not associated with simultaneous changes in their Grade Point Averages (GPAs), increases in the proportion of days spent helping the family were linked to declines in the GPAs of students from Mexican and Chinese backgrounds. The negative implications of spending more days helping the family among these two groups was not explained by family background factors or changes in study time or school problems. These results suggest that the chronicity rather than the amount of family assistance may be difficult for adolescents from Mexican and Chinese backgrounds.

The pursuit of happiness and reward is an impetus for everyday human behavior and the basis of well-being. Although optimal well-being may be achieved through eudaimonic activities (e.g., meaning and purpose), individuals tend to orient toward hedonic activities (e.g., pleasure seeking), potentially placing them at risk for ill-being. We implemented a longitudinal study and followed adolescents over 1 y to examine whether neural sensitivity to eudaimonic (e.g., prosocial decisions) and hedonic (e.g., selfish rewards and risky decisions) rewards differentially predicts longitudinal changes in depressive symptoms. Ventral striatum activation during eudaimonic decisions predicted longitudinal declines in depressive symptoms, whereas ventral striatum activation to hedonic decisions related to longitudinal increases in depressive symptoms. These findings underscore how the motivational context underlying neural sensitivity to rewards can differentially predict changes in well-being over time. Importantly, to our knowledge, this is the first study to show that striatal activation within an individual can be both a source of risk and protection.

Parental depression is a significant risk factor for adolescents' engagement in risk taking. Yet the neural processes that mediate the link between parental depression and adolescents' functioning remain unknown. Using a longitudinal functional magnetic resonance imaging design, we investigated how parental depression is associated with changes in adolescents' neural reactivity to rewards during a risk-taking task, and how such changes in neural reactivity are associated with changes in risk-taking behavior. Greater parental depressive symptoms were associated with increases in their adolescent child's risk taking and self-reported externalizing behavior over time. At the neural level, adolescents of parents with greater depressive symptoms showed longitudinal increases in the ventral striatum and dorsolateral prefrontal cortex to rewards during risk taking. Longitudinal increases in adolescents' ventral striatum activation mediates the link between greater parental depression and increases in adolescents' risk taking and externalizing behavior. These findings provide novel evidence that parental depression may contribute to changes in adolescents' neural reactivity to rewards over time, which is associated with greater increases in their risk taking and externalizing behavior.

Adolescence is a period of learning, exploration, and continuous adaptation to fluctuating environments. Response variability during adolescence is an important, understudied, and developmentally appropriate behavior. The purpose of this study was to identify the association between performance on a dynamic risky decision making task and white matter microstructure in a sample of 48 adolescents (14-16 years). Individuals with the greatest response variability on the task obtained the widest range of experience with potential outcomes to risky choice. When compared with their more behaviorally consistent peers, adolescents with greater response variability rated real-world examples of risk taking behaviors as less risky via self-report. Tract-Based Spatial Statistics (TBSS) were used to examine fractional anisotropy (FA) and mean diffusivity (MD). Greater FA in long-range, late-maturing tracts was associated with higher response variability. Greater FA and lower MD were associated with lower riskiness ratings of real-world risky behaviors. Results suggest that response variability and lower perceived risk attitudes of real-world risk are supported by neural maturation in adolescents.

An essential component of youths' successful development is learning to appropriately respond to emotions, including the ability to recognize, identify, and describe one's feelings. Such emotional competence is thought to arise through the parent-child relationship. Yet, the mechanisms by which parents transmit emotional competence to their children are difficult to measure because they are often implicit, idiosyncratic, and not easily articulated by parents or children. In the current study, we used a multifaceted approach that went beyond self-report measures and examined whether parental neural sensitivity to emotions predicted their child's emotional competence. Twenty-two adolescent-parent dyads completed an fMRI scan during which they labeled the emotional expressions of negatively valenced faces. Results indicate that parents who recruited the amygdala, VLPFC, and brain regions involved in mentalizing (i.e., inferring others' emotional states) had adolescent children with greater emotional competence. These results held after controlling for parents' self-reports of emotional expressivity and adolescents' self-reports of the warmth and support of their parent relationships. In addition, adolescents recruited neural regions involved in mentalizing during affect labeling, which significantly mediated the associated between parental neural sensitivity and adolescents' emotional competence, suggesting that youth are modeling or referencing their parents' emotional profiles, thereby contributing to better emotional competence.

Despite the known importance of sleep for brain development, and the sharp increase in poor sleep during adolescence, we know relatively little about how sleep impacts the developing brain. We present the first longitudinal study to examine how sleep during adolescence is associated with white matter integrity. We find that greater variability in sleep duration one year prior to a DTI scan is associated with lower white matter integrity above and beyond the effects of sleep duration, and variability in bedtime, whereas sleep variability a few months prior to the scan is not associated with white matter integrity. Thus, variability in sleep duration during adolescence may have long-term impairments on the developing brain. White matter integrity should be increasing during adolescence, and so sleep variability is directly at odds with normative developmental trends.

Adolescence is a critical developmental phase during which risk-taking behaviors increase across a variety of species, raising the importance of understanding how brain changes contribute to such behaviors. While the prefrontal cortex is thought to influence adolescent risk taking, the specific ways in which it functions are unclear. Using longitudinal functional magnetic resonance imaging in human adolescents, we found that ventrolateral prefrontal cortex (VLPFC) activation decreased during an experimental risk-taking task over time, with greater declines in VLPFC associated with greater declines in self-reported risky behavior. Furthermore, greater decreases in functional coupling between the medial prefrontal cortex (MPFC) and ventral striatum over time were associated with decreases in self-reported risky behavior. Thus, disparate roles of the VLPFC and MPFC modulate longitudinal declines in adolescent risk taking.

Significance statement

Adolescence is a developmental period marked by steep increases in risk-taking behavior coupled with dramatic brain changes. Although theories propose that the prefrontal cortex (PFC) may influence adolescent risk taking, the specific ways in which it functions remain unclear. We report the first longitudinal functional magnetic resonance imaging study to examine how neural activation during risk taking changes over time and contributes to adolescents' real-life risk-taking behavior. We find that longitudinal declines in activation of the ventrolateral PFC are linked to declines in adolescent risk taking, whereas the medial PFC influences adolescent risk taking via its functional neural coupling with reward-related regions. This is the first study to identify the mechanism by which different regions of the PFC disparately contribute to declines in risk taking.

Adolescents' peer culture plays a key role in the development and maintenance of risk-taking behavior. Despite recent advances in developmental neuroscience suggesting that peers may increase neural sensitivity to rewards, we know relatively little about how the quality of peer relations impact adolescent risk taking. In the current 2-year three-wave longitudinal study, we examined how chronic levels of peer conflict relate to risk taking behaviorally and neurally, and whether this is modified by high-quality peer relationships. Forty-six adolescents completed daily diaries assessing peer conflict across 2 years as well as a measure of peer support. During a functional brain scan, adolescents completed a risk-taking task. Behaviorally, peer conflict was associated with greater risk-taking behavior, especially for adolescents reporting low peer support. High levels of peer support buffered this association. At the neural level, peer conflict was associated with greater activation in the striatum and insula, especially among adolescents reporting low peer support, whereas this association was buffered for adolescents reporting high peer support. Results are consistent with the stress-buffering model of social relationships and underscore the importance of the quality of adolescents' peer relationships for their risk taking.

The consequences of risky sexual behavior are of public concern. Adolescents contribute disproportionately to negative consequences of risky sexual behavior. However, no research has examined the neural correlates of impulse control and real-world engagement in risky sexual behavior in this population. The aim of the present study was to examine this question. Twenty sexually active adolescents performed an impulse control task during a functional magnetic resonance imaging (fMRI) scan and risky sexual behaviors were assessed through self-report. Sexual riskiness ratings were negatively associated with activation in the prefrontal cortex during response inhibition. These results suggest that diminished engagement of impulse control circuitry may contribute to sexual riskiness in adolescents.