The Effect of Relative Pubertal Maturation and Perceived Popularity on Symptoms of Depression and Social Anxiety in Adolescent Boys and Girls.

Research has shown that adolescents - particularly girls - who mature relatively early often experience more internalizing problems. This effect is thought to be partially driven by psychosocial mechanisms, but previous research based relative pubertal maturation on complete samples or population standards, instead of considering the adolescents' direct peer environment. In the current study the level of adolescents' pubertal development was assessed relative to their classmates in order to examine relative pubertal maturation. The effects of adolescents' relative pubertal status, and their perceived popularity, on symptoms of social anxiety and depression in adolescents were studied. All analyses were also performed for absolute pubertal maturation. Participants were 397 young adolescents (Mage = 13.06, SD = 0.36, 49.9% girls) at timepoint 1, and 307 (Mage = 14.08, SD = 0.36, 50.5% girls) at timepoint 2. A significant positive relationship was found between relative pubertal timing and symptoms of depression for girls but not boys. Social anxiety symptoms were not significantly related to relative pubertal timing in either sex. Relative pubertal maturation had no effect on change in or persistence of depressive and social anxiety symptoms one year later. The effects of the comparison with the immediate peer environment, did not seem to explain more variance in internalizing symptoms than the effects of early maturation.

Longitudinal assessment of amygdala activity in mice susceptible to trauma.

Resilience to consequences of trauma exposure contains relevant information about the processes that contribute to the maintenance of mental health in the face of adversity; information that is essential to improve treatment success of stress-related mental diseases. Prior literature has implicated aberrant amygdala (re)activity as potential factor contributing to trauma susceptibility. However, it remains to be resolved which amygdalar subregions and neuronal subclasses are involved, and when - i.e., pre-, peri- or post-trauma exposure - and under what conditions changes in amygdala (re)activity manifest themselves. Here, we implemented a preclinical rodent model for PTSD that entailed exposure to a traumatic event (severe, unpredictable foot shock) followed by a trigger (mild, predictable foot shock). Using behavioral phenotyping, trauma susceptible vs. resilient mice were identified and pre-, peri- or post-trauma amygdala activity was compared. Neuronal activity was tagged in living mice by the use of the ArcTRAP transgenic mouse line, labeling all activated (i.e., Arc-expressing) neurons by a systemic injection of tamoxifen. Furthermore, we assessed amygdala responses during fear memory recall, induced by either (re-)exposure to the trauma, trigger, or a novel, yet similar context, and analyzed behavioral fear responses under these conditions, as well as basal anxiety in the mice. Results revealed no major differences dissociating susceptible vs. resilient mice prior to trauma exposure, but exaggerated activity in specifically the basolateral amygdala (BLA) peri-trauma that predicted susceptibility to later PTSD-like symptoms. Post-trauma, susceptible mice did not display altered basal amygdala activity, but BLA hyperreactivity in response to trigger context re-exposure, and BLA hyporesponsivity in response to the trauma context. Exposure to the novel, similar context evoked a differential temporal pattern of freezing behavior in susceptible mice and an increased activity of amygdalar somatostatin-expressing neurons specifically. As such, these results for the first time show that deviant BLA activity during fear learning predicts susceptibility to its long-term consequences and that aberrant subsequent BLA responses to stressful contexts depend on the exact context.

Development of the neural correlates of self- and other-referential processing across adolescence.

During adolescence, major changes in brain mechanisms take place and differentiated representations of both the self and of others are developed. Although studies have investigated the neural mechanisms of self- and other-referential processing in adolescents, the development of these mechanisms remain largely unaddressed. Here, we report a three-year longitudinal study with annual measurements, and investigate the developmental trajectories of activity and connectivity underlying self- and other-referential processes in 34 participants from early to mid-adolescence (mean age timepoints 1, 2, 3 = 12.9, 13.9, 15.0 years). Moreover, we probe whether these correlates continue to develop from mid-adolescence to young adulthood by comparing neural correlates of the adolescents at the last measurement to an independent group of 42 young adults (mean age 22 years). Participants underwent functional MRI while performing a trait judgement task in which they indicated whether an adjective described themselves, a similar or a dissimilar peer. Brain activity within the dorsal medial prefrontal cortex (dMPFC) and right temporal parietal junction (TPJ) showed a quadratic change from early to mid-adolescence, with a peak in activity at the second measurement when evaluating the self, the similar and dissimilar peer. No differential activity was observed when comparing the adolescents to young adults. Functional connectivity did not change from early to mid-adolescence, however, connectivity of the dMPFC with a posterior midline region during self- and other-referential processing relative to the control condition reduced from mid-adolescence to young adulthood. Together, these findings provide insight in the developmental trajectories of brain activity and connectivity underlying the development of the self-concept and representations of peers in adolescence.