BACKGROUND: This study aimed to identify the developmental trajectories of loneliness in Chinese children and examine the predictive roles of domain-specific environmental factors (i.e., family dysfunction and satisfaction of relatedness needs at school), personality factors (i.e., neuroticism and extraversion), and their interactions in these developmental trajectories.
METHODS: A total of 702 Chinese children (Mage = 8.95, SD = 0.76; 54.1 % boys) participated in assessments at six time points over three years at six-month intervals. Growth mixture modeling (GMM) was used to estimate trajectory classes for loneliness, followed by multivariate logistic regression analyses exploring associations between these classes and predictors.
RESULTS: GMM analyses identified three distinct trajectories of loneliness: \"low-stable\" (81.5 %), \"moderate-increasing\" (9.4 %), and \"high-decreasing\" (9.1 %). Multivariate logistic regression analyses revealed that family dysfunction and neuroticism served as risk factors for adverse loneliness trajectories, while satisfaction of relatedness needs at school and extraversion acted as protective factors. Furthermore, the interaction between family dysfunction and extraversion indicated that extraversion did not mitigate the adverse effects of high family dysfunction on children\'s loneliness, emphasizing the vital need to support positive family functioning among all children.
CONCLUSIONS: This study did not incorporate biological variables (e.g., genetics), which are crucial in the evolutionary theory of loneliness.
CONCLUSIONS: The identification of three distinct trajectory groups of children\'s loneliness, along with key environmental and personality predictors, suggests that interventions should be tailored to each group\'s unique characteristics.

Transactional sex and sexual relationships with older partners increase HIV risk in adolescent girls and young women (AGYW), yet little is known about how these behaviors co-evolve over time. We characterize temporal patterns of transactional sex and age-disparate relationships among AGYW in South Africa. Longitudinal data are from a randomized controlled trial (HPTN 068) of school-aged, HIV-negative, AGYW who attended ≥ 3 study visits. We used group-based trajectory modeling to identify trajectories of transactional sex and age-disparate relationships (partner ≥ 5 years older) in the last year and assessed the interrelationship (conditional probability) between both trajectories. At baseline, median age was 14 years, 14.5% of girls were sexually active, and transactional sex (2.1%) and age-disparate relationships were uncommon (2.7%). We identified two trajectories for transactional sex (\"low\" [81.9%] and \"increasing\" [18.1%]) and two for age-disparate relationships (\"low\" [91.7%] and \"increasing\" [8.3%]). In a separate joint trajectory analysis, nearly a third (28%) had increasing trajectories for both transactional sex and age-disparate relationships, but most (53%) had a low trajectory of both outcomes. Baseline reporting of early sexual debut, depression, and inequitable gender norms were highest in the increasing transactional sex group. Prior pregnancy, early sexual debut, and IPV were highest among those with increasing age-disparate relationships. AGYW who engage in transactional sex or age-disparate partnerships in early adolescence are more likely to experience sustained engagement in both behaviors as they transition to adulthood, increasing HIV risk. Engaging girls early may maximize effectiveness of behavioral and biomedical HIV prevention efforts.

UNASSIGNED: Few studies have examined how multi-level social factors interact and affect developmental patterns of sexual risk among middle-to-late adolescents who are at risk of experiencing sexual risk behaviors. We examined developmental trajectories of sexual risk behaviors of boys and girls in middle-to-late adolescence and the effects of exposure to three social risk factors (poor parental monitoring, peer risk, and neighborhood risk).
UNASSIGNED: We followed 2,332 Bahamian adolescents every six months from Grades 10-12. We used group-based trajectory modeling to identify distinct trajectories of sexual risk behaviors for boys and girls.
UNASSIGNED: We identified three trajectories each for boys and girls. Peer risk and neighborhood risk predicted a high sexual-risk trajectory for boys, and peer risk (alone or combined with other risk factors) had the greatest impact on the membership of moderate-to-high-risk trajectory for girls. Parental monitoring had a relatively small effect on adolescents\' sexual risk behavior.
UNASSIGNED: Our results underscore the importance of early identification of adolescents with sexual risk behavior and development of targeted prevention interventions to improve adolescent health outcomes.

Several neurodevelopmental disorders are associated with a higher prevalence of atypical laterality (e.g., left-handedness). Both genetic and non-genetic factors play a role in this association, yet the underlying neurobiological mechanisms are largely unclear. Recent studies have found that stress, mediated by the hypothalamic-pituitary-adrenal (HPA) axis, could be linked to laterality development. These findings provide an opportunity to explore new theoretical perspectives on the association between atypical laterality and neurodevelopmental disorders. This article aims to provide a theoretical framework demonstrating how perinatal adversities could disrupt the typical developmental trajectories of both laterality and neurodevelopment, potentially impacting both the HPA axis and the vestibular system. Additionally, we argue that the relationship between atypical laterality and neurodevelopmental disorders cannot be understood by simply linking genetic and non-genetic factors to a diagnosis, but the developmental trajectories must be considered. Based on these ideas, several perspectives for future research are proposed.

Play is thought to serve different purposes at different times during ontogeny. The nature and frequency of play are expected to change accordingly over the developmental trajectory and with socio-ecological context. Orangutans offer the opportunity to disentangle the ontogenetic trajectories of solitary and social play with their extended immature phase, and socio-ecological variation among populations and species. We evaluated the frequency of play in 39 immature individuals across two populations (Pongo pygmaeus wurmbii, at Tuanan, Borneo, and P. abelii at Suaq, Sumatra), age (0-11 years), sex, and social context, using more than 11 500 h of full-day focal observation data. We found independent age trajectories of different play types, with solitary object and solitary locomotor peaking before social play. Social play partners changed during ontogeny, and male immatures were more likely to engage in non-mother social play than females. Overall, social play was more frequent at Suaq than Tuanan, linked to the more frequent availability of partners. Furthermore, per time in association with conspecifics, Tuanan immatures were as likely to engage in social play as their peers at Suaq, suggesting similar intrinsic motivation. Increasing fruit availability correlated with both longer associations and increased social play frequency in the less sociable population of Tuanan, but not at Suaq. Our findings on orangutans support evidence from other species that different play types follow different developmental trajectories, vary with sex, social opportunities, and ecological context. Although drawing functional inferences is challenging, the distinct developmental trajectories reflecting adult sociability and behavioral repertoires may indicate that play serves several, non-mutually exclusive functions during ontogeny.
UNASSIGNED: The online version contains supplementary material available at 10.1007/s10764-023-00414-2.

Early sensory differences may cascade into later social-communication difficulties in autism, yet their impacts on broader functional outcomes have remained understudied. This study aimed to conduct a comprehensive investigation into the longitudinal impacts of sensory patterns, including sensory hyperresponsiveness, hyporesponsiveness, and sensory repetitions/seeking behavior, on various school-age outcome domains among a community sample of children with autistic and non-autistic conditions. We prospectively followed 1,517 children with caregiver-reported sensory questionnaires across three timepoints from infancy to school age. A subsample (n = 389; 88 with reported autism diagnosis/concerns) was further assessed with adaptive, maladaptive and participation outcome measures at age 6-7. Structural equation modeling approaches were used to evaluate the multivariate associations between latent growth parameters (i.e., intercepts and slopes) of sensory patterns and school-age outcomes. Increasing sensory hyperresponsiveness was directly associated with poorer adaptive/maladaptive outcomes and indirectly with lower participation in activities with higher functional demands across settings at school age. Elevated sensory hyporesponsiveness was associated with lower adaptive functioning, more externalizing problems, and lower classroom participation. Trajectories of sensory patterns accounted for more unique variances in adaptive functioning and participation in daily life settings with higher functional and environmental demands among autistic children compared to their non-autistic peers.

UNASSIGNED: Recent research has revealed informative patterns about health, mental health, self-help skills, autism symptoms, and social skills during the transition to adulthood for autistic individuals. This study expands on these findings by examining how positive affect (e.g. excited) changes from age 15 to 30 years using a group of individuals first referred for autism at an early age. We also examined the agreement between caregiver-report and self-report on positive affect. We found different patterns of stability and change in positive affect across the transition to adulthood that related to differences in autism severity, cognitive abilities, self-help skills, as well as social and work participation in adulthood. The agreement between caregiver-report and self-report was strong in adolescence but became much weaker after the individuals were 23 years. These results have implications for how we measure happiness, positive emotions, or other internal experiences of autistic individuals.

OBJECTIVE: This study aimed to examine the developmental relationships between achievement goals and affect in school physical education.
METHODS: The study sample comprised 1063 (girls 546) Finnish Grade 6 students (M = 12.27 years ± 0.33 at the beginning of the study). The participants in the study were asked to provide annual assessments about their perceptions of achievement goals, enjoyment, and anxiety. The assessments were conducted four times over three consecutive years.
RESULTS: The results indicated that mastery-approach goals were positively associated with enjoyment (between-level), whereas both mastery-avoidance and performance-avoidance goals were positively associated with anxiety (between-level). Additionally, the associations between repeated measures (within-level) of mastery-approach goals and enjoyment were similar each year, whereas mastery- and performance-approach/avoidance goals were consistently associated with anxiety within the same year. Girls reported lower performance-approach goals and enjoyment but higher mastery-avoidance goals and anxiety than boys.
CONCLUSIONS: The findings suggest that mastery approach goals exhibit a positive correlation with favorable affective reactions, while performance-avoidance goals demonstrate a connection with maladaptive responses. Physical education teachers should endeavor to establish mastery-oriented goals for their students from the outset of the educational process.

OBJECTIVE: In the context of developmental trajectories, the association between adaptive functioning and core autism symptomatology remains unclear. The current study examines the associations of adaptive behavior with autism symptom sub-domains and with different facets of symptom expression.
METHODS: Participants include 36 children with a recent diagnosis of autism (33 males; mean age = 56.4 months; SD = 9 months). Families were recruited in the context of the Pediatric Autism Research Cohort (PARC) project. Parents filled out questionnaires at two time points, six months apart, regarding their child\'s autism symptoms and adaptive functioning. The longitudinal relationship between adaptive functioning and autism symptoms was investigated using Mixed Linear Model analyses: one assessing the relationship between general symptom levels and adaptive functioning, and another examining the associations between symptom frequency and impact with adaptive functioning. We conducted Pearson correlation tests at both time points to assess the associations between symptom sub-domains and adaptive functioning.
RESULTS: Findings showed that higher autism symptoms associated with lower adaptive behavior skills, and that this association remained stable over time. Autism impact scores did not significantly relate to adaptive skills, as opposed to frequency scores. Associations between adaptive functioning and autism symptom sub-domains strengthened over time.
CONCLUSIONS: These findings suggest that adaptive functioning is associated with parent-report autism symptomatology, and that this association changes and, on average, becomes stronger over time. Findings may indicate that frequency and impact of symptoms have differential roles in the development of adaptive skills and are worthy of further exploration.

OBJECTIVE: Rett syndrome (RTT) is characterized by neurological regression. This pioneering study investigated the effect of age on brain volume reduction by analyzing magnetic resonance imaging findings in participants with RTT, ranging from toddlers to adults.
METHODS: Functional evaluation and neuroimaging were performed. All scans were acquired using a Siemens Tim Trio 3 T scanner with a 32-channel head coil.
RESULTS: The total intracranial volume and cerebral white matter volume significantly increased with age in the control group compared with that in the RTT group (p < 0.05). Cortical gray matter volume reduction in the RTT group continued to increase in bilateral parietal lobes and left occipital lobes (p < 0.05). The differences in cortical gray matter volume between typically developing brain and RTT-affected brain may tend to continuously increase until adulthood in both temporal lobes although not significant after correction for multiple comparison.
CONCLUSIONS: A significant reduction in brain volume was observed in the RTT group. Cortical gray matter volume in the RTT group continued to reduce in bilateral parietal lobes and left occipital lobes. These results provide a baseline for future studies on the effect of RTT treatment and related neuroscience research.