Distinct Developmental Patterns Research Articles

Trajectories of depressive symptoms in early to mid-adolescence: associations with school pedagogical and social climate.

Adolescence is a critical period for mental health development, yet research exploring how contextual factors influence the development of depressive symptoms remains limited. This study explored trajectories of depressive symptoms during early to mid-adolescence and their association with various aspects of school climate. The study sample comprised 3671, 7th-grade students (aged 12-13 years) from 101 schools across Sweden, followed longitudinally across three time points spanning grades 7, 8 and 9. Depressive symptom trajectories were identified using latent class growth modelling. The Pedagogical and Social Climate questionnaire assessed school climate, and multinomial logistic regression was employed to predict trajectory membership based on sociodemographic and school climate factors. Four distinct developmental patterns of depressive symptoms emerged: 'Sustained low symptoms' (76.7%), 'Low-increasing' (10.9%), 'Sustained high symptoms' (7.9%), and 'High-decreasing' (4.5%). Gender, parental education and six specific school climate factors, out of the total 19 examined, significantly distinguished these trajectory classes. Positive teacher expectations and strong principal involvement were associated with more favourable trajectories, whereas teaching activities, teacher support and communication between school and home were associated with less favourable trajectories, suggesting a nuanced understanding of their relationship with depressive symptom trajectories. Few school factors were found to be relevant to depressive symptoms, highlighting the importance of considering external factors beyond the school environment in supporting adolescents during this developmental stage. Although the findings are multifaceted, it is primarily positive interpersonal relationships, especially through teacher expectations, that stand out as significant factors in promoting youth mental health.

Transcriptomic analysis reveals differential gene expression patterns during cannabis leaf morphogenesis and phase transition

ABSTRACT Understanding the molecular mechanisms governing leaf morphogenesis and phase transition in Cannabis sativa is critical for optimizing its growth, development and yield. In this study, we conducted a comparative transcriptomic analysis to investigate the gene expression patterns associated with leaf development and the transition from vegetative to reproductive phases in cannabis plants. Following germination, cannabis plants display a distinct leaf developmental pattern. While the specific number of leaflets varies among cultivars, here we focused on the White Widow cultivar as a model. It showed an increase in the number of serrated leaflets from one (L1) to nine (L5) in a node-specific manner. Subsequently, the number of leaflets decreased from eight (L6) to three (L9). The transition from vegetative to reproductive phases, marked by the appearance of solitary flowers and a shift from opposite to alternate leaf phyllotaxy, occurred at node 7 and node 12, respectively. Analysis of gene expression revealed 1358 differentially expressed genes, with 1,182 genes showing differential expression across all leaves. Notably, several genes involved in leaf morphogenesis (e.g. YAB, AGO5, and TCP4) were found to be upregulated in compound leaves (L2) compared to simple leaves (L1), implying a role in leaflet formation and overall leaf morphology. Furthermore, several genes associated with phase transition and flowering (e.g. SPLs, ELFs, SOC1, and CEN-Like) exhibited specific expression patterns during the transition from vegetative to reproductive phases. These findings provide valuable insights into the genetic regulation of leaf morphogenesis and phase transition in cannabis.

Single cell dual-omic atlas of the human developing retina

The development of the retina is under tight temporal and spatial control. To gain insights into the molecular basis of this process, we generate a single-nuclei dual-omic atlas of the human developing retina with approximately 220,000 nuclei from 14 human embryos and fetuses aged between 8 and 23-weeks post-conception with matched macular and peripheral tissues. This atlas captures all major cell classes in the retina, along with a large proportion of progenitors and cell-type-specific precursors. Cell trajectory analysis reveals a transition from continuous progression in early progenitors to a hierarchical development during the later stages of cell type specification. Both known and unrecorded candidate transcription factors, along with gene regulatory networks that drive the transitions of various cell fates, are identified. Comparisons between the macular and peripheral retinae indicate a largely consistent yet distinct developmental pattern. This atlas offers unparalleled resolution into the transcriptional and chromatin accessibility landscapes during development, providing an invaluable resource for deeper insights into retinal development and associated diseases.

Association between developmental patterns of single and concurrent externalizing behaviors and internalizing problems over the preschool years.

The present study investigated whether distinct developmental patterns of externalizing behaviors (EBs: hyperactivity-impulsivity, noncompliance, physical aggression) based on parent reports were repeatedly and differentially associated with separate dimensions of internalizing problems such as general anxiety, separation anxiety, and depressive symptoms across the early, middle, and late preschool years in a population birth cohort (N = 2,057, 50.7% boys). Six high trajectory classes obtained by latent growth modeling were used as longitudinal indicators of single EB and co-occurrent EBs. Children following low or moderate trajectories for all EBs served as the reference class. Results revealed that children in trajectory classes reflecting high levels of co-occurring EBs showed higher levels of general anxiety, separation anxiety, and depressive symptoms across the preschool years. In contrast, children in trajectory classes reflecting single EB manifested higher levels of some, but not all, dimensions of internalizing problems. In addition, their scores varied from one period to another. No sex differences were observed in the above associations. These results underline the need for comprehensive assessments across distinct types of EBs and internalizing problems to better reflect the characteristics that distinguish individual children. Finally, results suggest that children showing early co-occurrent EBs and internalizing symptoms may be an important group to target for in-depth assessment and possibly preventive intervention. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

High-resolution diffusion magnetic resonance imaging and spatial-transcriptomic in developing mouse brain

Brain development is a highly complex process regulated by numerous genes at the molecular and cellular levels. Brain tissue exhibits serial microstructural changes during the development process. High-resolution diffusion magnetic resonance imaging (dMRI) affords a unique opportunity to probe these changes in the developing brain non-destructively. In this study, we acquired multi-shell dMRI datasets at 32 µm isotropic resolution to investigate the tissue microstructure alterations, which we believe to be the highest spatial resolution dMRI datasets obtained for postnatal mouse brains. We adapted the Allen Developing Mouse Brain Atlas (ADMBA) to integrate quantitative MRI metrics and spatial transcriptomics. Diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), and neurite orientation dispersion and density imaging (NODDI) metrics were used to quantify brain development at different postnatal days. We demonstrated that the differential evolutions of fiber orientation distributions contribute to the distinct development patterns in white matter (WM) and gray matter (GM). Furthermore, the genes enriched in the nervous system that regulate brain structure and function were expressed in spatial correlation with age-matched dMRI. This study is the first one providing high-resolution dMRI, including DTI, DKI, and NODDI models, to trace mouse brain microstructural changes in WM and GM during postnatal development. This study also highlighted the genotype-phenotype correlation of spatial transcriptomics and dMRI, which may improve our understanding of brain microstructure changes at the molecular level.

Multidimensional trajectories of Chinese undergraduates’ English speaking self-efficacy: Developmental patterns and influencing factors

This longitudinal study tracked the development of multidimensional English speaking self-efficacy among 335 Chinese college students over one semester, aiming to identify developmental patterns and influencing factors across different dimensions and patterns. Growth Mixture Modeling results revealed distinct patterns of development in different dimensions of English speaking self-efficacy. Regarding self-efficacy for oral tasks, two patterns emerged: “higher initial level with a significant increase” and “lower initial level with a significant increase.” Self-efficacy for complexity showed two patterns as well: “higher initial level with no significant change” and “lower initial level with a significant increase.” Similarly, self-efficacy for self-regulated learning also exhibited two patterns: “higher initial level with an insignificant decrease” and “lower initial level with an insignificant increase.” On the other hand, self-efficacy for accuracy and self-efficacy for fluency displayed a single pattern each, both indicating a “significant increase.” These findings indicate the presence of non-linearity and heterogeneity in the development of English-speaking self-efficacy. Furthermore, the study identified diverse factors that influence the development of English-speaking self-efficacy, including mastery experience, emotional states, and practice, among others. Notably, these influencing factors varied across different dimensions and developmental patterns.

Investigating grey matter volumetric trajectories through the lifespan at the individual level

Adolescents exhibit remarkable heterogeneity in the structural architecture of brain development. However, due to limited large-scale longitudinal neuroimaging studies, existing research has largely focused on population averages, and the neurobiological basis underlying individual heterogeneity remains poorly understood. Here we identify, using the IMAGEN adolescent cohort followed up over 9 years (14–23 y), three groups of adolescents characterized by distinct developmental patterns of whole-brain gray matter volume (GMV). Group 1 show continuously decreasing GMV associated with higher neurocognitive performances than the other two groups during adolescence. Group 2 exhibit a slower rate of GMV decrease and lower neurocognitive performances compared with Group 1, which was associated with epigenetic differences and greater environmental burden. Group 3 show increasing GMV and lower baseline neurocognitive performances due to a genetic variation. Using the UK Biobank, we show these differences may be attenuated in mid-to-late adulthood. Our study reveals clusters of adolescent neurodevelopment based on GMV and the potential long-term impact.

What do measures of gender identity tell us about gender identity over time?

Gender identity is a multifaceted concept and is represented by a wide range of measures and constructs including both self-report and researcher observations of preferences and behaviours. However, despite their similar theoretical underpinning, gender identity measures are rarely found to correlate with one another, and contrasting patterns and trajectories are often found for each construct (Egan & Perry, Developmental Psychology, 37, 2001, 451). Therefore, this systematic review aimed to present a review of the longitudinal research evidence surrounding gender identity development in the absence of formal intervention. Using a systematic search strategy, 21 studies were identified. Narrative synthesis was used to synthesize the data collected in these studies and trajectories were explored for (1) self-identification measures of gender identity, (2) clothing preferences, (3) peer preferences, and (4) object/activity preferences. Overall, the results of this systematic review are consistent with wider research suggesting that distinct developmental patterns can be observed when using different constructs and measures of gender identity.

Serological profiling of pneumococcal proteins reveals unique patterns of acquisition, maintenance and waning of antibodies throughout life.

Streptococcus pneumoniae is a leading cause of morbidity and mortality in children and older adults. Yet knowledge on the development of pneumococcal protein-specific antibody responses throughout life is limited. To investigate this, we measured serum IgG levels to 55 pneumococcal proteins in 11-month old infants (n=73), 24-month old children (n=101), parents (n=99), adults without children <6 years of age (n= 99) and older adults aged >60 years (n=100). Our findings revealed low IgG levels in infancy, with distinct development patterns peaking in adults. A decrease in levels was observed for 27 antigens towards older age. Adults and older adults had increased IgG levels during pneumococcal carriage and at increased exposure risk to S. pneumoniae. Carriage was a stronger predictor than exposure or age for antibody responses. These findings highlight the dynamic nature of naturally acquired humoral immunity to pneumococcal proteins throughout life, offering insights for age-targeted interventions.

The two C. elegans class VI myosins, SPE-15/HUM-3 and HUM-8, share similar motor properties, but have distinct developmental and tissue expression patterns.

Myosins of class VI move toward the minus-end of actin filaments and play vital roles in cellular processes such as endocytosis, autophagy, protein secretion, and the regulation of actin filament dynamics. In contrast to the majority of metazoan organisms examined to date which contain a single MYO6 gene, C. elegans, possesses two MYO6 homologues, SPE-15/HUM-3 and HUM-8. Through a combination of in vitro biochemical/biophysical analysis and cellular assays, we confirmed that both SPE-15/HUM-3 and HUM-8 exhibit reverse directionality, velocities, and ATPase activity similar to human MYO6. Our characterization also revealed that unlike SPE-15/HUM-3, HUM-8 is expressed as two distinct splice isoforms, one with an additional unique 14 amino acid insert in the cargo-binding domain. While lipid and adaptor binding sites are conserved in SPE-15/HUM-3 and HUM-8, this conservation does not enable recruitment to endosomes in mammalian cells. Finally, we performed super-resolution confocal imaging on transgenic worms expressing either mNeonGreen SPE-15/HUM-3 or wrmScarlet HUM-8. Our results show a clear distinction in tissue distribution between SPE-15/HUM-3 and HUM-8. While SPE-15/HUM-3 exhibited specific expression in the gonads and neuronal tissue in the head, HUM-8 was exclusively localized in the intestinal epithelium. Overall, these findings align with the established tissue distributions and localizations of human MYO6.

The political economy of illicit drug crops: forum introduction

ABSTRACT This article and the forum it introduces examine illicit drug crop (IDC) economies from agrarian perspectives. Examining IDCs as a group implies analysing how prohibition distinguishes them from other (licit) crops. We identify seven mechanisms through which prohibition shapes the agrarian political economy of IDCs and explore how these mechanisms and their effects generate distinctive patterns of development and political action amongst ‘illicit peasantries’. We also examine connections between illicit and licit crops, including how licit crop crises and illicit crop booms intertwine. We argue that IDC economies provide a bulwark for smallholders but are by no means peasant idylls.

Developmental expression of catecholamine system in the human placenta and rat fetoplacental unit

Catecholamines norepinephrine and dopamine have been implicated in numerous physiological processes within the central nervous system. Emerging evidence has highlighted the importance of tightly regulated monoamine levels for placental functions and fetal development. However, the complexities of synthesis, release, and regulation of catecholamines in the fetoplacental unit have not been fully unraveled. In this study, we investigated the expression of enzymes and transporters involved in synthesis, degradation, and transport of norepinephrine and dopamine in the human placenta and rat fetoplacental unit. Quantitative PCR and Western blot analyses were performed in early-to-late gestation in humans (first trimester vs. term placenta) and mid-to-late gestation in rats (placenta and fetal brain, intestines, liver, lungs, and heart). In addition, we analyzed the gene expression patterns in isolated primary trophoblast cells from the human placenta and placenta-derived cell lines (HRP-1, BeWo, JEG-3). In both human and rat placentas, the study identifies the presence of only PNMT, COMT, and NET at the mRNA and protein levels, with the expression of PNMT and NET showing gestational age dependency. On the other hand, rat fetal tissues consistently express the catecholamine pathway genes, revealing distinct developmental expression patterns. Lastly, we report significant transcriptional profile variations in different placental cell models, emphasizing the importance of careful model selection for catecholamine metabolism/transport studies. Collectively, integrating findings from humans and rats enhances our understanding of the dynamic regulatory mechanisms that underlie catecholamine dynamics during pregnancy. We identified similar patterns in both species across gestation, suggesting conserved molecular mechanisms and potentially shedding light on shared biological processes influencing placental development.

Distinct developmental patterns in Anopheles stephensi organ systems

Anatomical profiles of insects inform vector biology, comparative development and evolutionary studies with applications in forensics, agriculture and disease control. This study presents a comprehensive, high-resolution developmental profile of Anopheles stephensi, encompassing larval, pupal, and adult stages, obtained through microCT scanning. The results indicate in situ anatomical changes in most organ systems, including the central nervous system, eyes, musculature, alimentary canal, salivary glands, and ovaries, among other organ systems, except for the developing heart. We find significant differences in the mosquito gut, body-wall, and flight muscle development during metamorphosis from other dipterans like Drosophila. Specifically, indirect flight muscle specification and growth can be traced back at least to the 4th instar A. stephensi larvae, as opposed to post-puparial development in other Dipterans like Drosophila and Calliphora. Further, while Drosophila larval body-wall muscles and gut undergo histolysis, changes to these organs during mosquito metamorphosis are less pronounced. These observations, and raw data therein may serve as a reference for studies on the development and the genetics of mosquitoes. Overall, the detailed developmental profile of A. stephensi presented here illuminates the unique anatomy and developmental processes of Culicidae, with important implications for vector biology, disease control, and comparative evolutionary studies.

The value of ecosystem services in arid and semi-arid regions: A multi-scenario analysis of land use simulation in the Kashgar region of Xinjiang

This study aimed to investigate the interrelationships between land use/land cover (LULC) and ecosystem services value (ESV) in arid and semi-arid regions, with a specific focus on the Kashgar region in Xinjiang, China. Four distinct development patterns (BAU, RED, ELP, and EBB) were derived using a multi-objective planning algorithm (MOP), and the relationship between LULC and ESV was analyzed using three methods: the random forest algorithm, the PLUS model, and the ecosystem service equivalence method. The findings indicated a significant projected expansion of LULC in Kashgar by 2030, primarily concentrated in arable and construction land. The ELP scenario demonstrated the lowest growth in cultivated and urbanized land, while the BAU and RED scenarios exhibited higher increments. Notably, the expansion of arable and construction land was concentrated around the urban agglomeration of the Kashgar region, whereas changes in forest land were concentrated near the Kunlun Mountains. Regarding ESV, grassland and watersheds played a significant role, accounting for 45 % and 30 % of the total, grasslands and watersheds emerge as pivotal components in supporting biodiversity, soil preservation, water regulation, and purification. The study underscores the necessity of conserving these ecosystems. This study highlights the trade-offs between economic development and ecological/environmental protection. The RED scenario, driven by rapid economic growth and urbanization, has resulted in a significant decline in ESVs, underscoring the urgency of sustainable land use practices. The MOP-PLUS-ESV model used in this study provides a powerful framework for decision makers to make informed choices in land use planning. By prioritizing a balance between economic development and ecological preservation, the model contributes to sustainable community and regional growth, emphasizing the preservation of important ecosystems. The findings suggest that Kashgar needs to adopt a sustainable land use strategy that balances economic development and ecological/environmental protection to maximize the provision and protection of ESV. The pathway emphasizes the integrated consideration of ESV, rational land use policies, and enhanced ecological protection to achieve an ecological civilization.

Revealing chronic disease progression patterns using Gaussian process for stage inference.

The early stages of chronic disease typically progress slowly, so symptoms are usually only noticed until the disease is advanced. Slow progression and heterogeneous manifestations make it challenging to model the transition from normal to disease status. As patient conditions are only observed at discrete timestamps with varying intervals, an incomplete understanding of disease progression and heterogeneity affects clinical practice and drug development. We developed the Gaussian Process for Stage Inference (GPSI) approach to uncover chronic disease progression patterns and assess the dynamic contribution of clinical features. We tested the ability of the GPSI to reliably stratify synthetic and real-world data for osteoarthritis (OA) in the Osteoarthritis Initiative (OAI), bipolar disorder (BP) in the Adolescent Brain Cognitive Development Study (ABCD), and hepatocellular carcinoma (HCC) in the UTHealth and The Cancer Genome Atlas (TCGA). First, GPSI identified two subgroups of OA based on image features, where these subgroups corresponded to different genotypes, indicating the bone-remodeling and overweight-related pathways. Second, GPSI differentiated BP into two distinct developmental patterns and defined the contribution of specific brain region atrophy from early to advanced disease stages, demonstrating the ability of the GPSI to identify diagnostic subgroups. Third, HCC progression patterns were well reproduced in the two independent UTHealth and TCGA datasets. Our study demonstrated that an unsupervised approach can disentangle temporal and phenotypic heterogeneity and identify population subgroups with common patterns of disease progression. Based on the differences in these features across stages, physicians can better tailor treatment plans and medications to individual patients.

The road to language through gesture

Abstract This study explores the role of gestures in Flemish Sign Language (VGT) development through a longitudinal observation of three deaf children’s early interactions. These children were followed over a period of one and a half year, at the ages of 6, 9, 12, 18 and 24 months. This research compares the communicative development of a deaf child growing up in a deaf family and two deaf children growing up in hearing families. The latter two children received early cochlear implants when they were respectively 10 and 7 months old. It is the first study describing the types and tokens of children’s gestures used in early dyadic interactions in Flanders (Belgium). The description of our observations shows three distinct developmental patterns in terms of the use of gestures and the production of combinations. The study supports the finding that children’s gestural output is subject to their parental language, and it further indicates an impact of age of cochlear implantation.

Determinants of long-term sickness absence trajectories among 19–39-year-old employees with pain

Abstract Background Previous studies have shown higher long-term sickness absence (LTSA) rates among employees with pain as compared to those not reporting pain. We examined distinct developmental patterns in LTSA (≥10 consecutive working days) among young and early midlife employees with pain at baseline, and factors associated with LTSA trajectories. Methods The study population consisted of 19-39-year-old employees (n = 1685) of the City of Helsinki who reported current pain at baseline in 2017. Data on all-cause LTSA days through March 2020 were collected from the Social Insurance Institution of Finland. Group-based trajectory modelling was used to identify distinct all-cause LTSA trajectories. Multinomial logistic regression was used to examine associations of pain characteristics, lifestyle- and occupational factors with trajectory group membership. Results Three distinct LTSA-trajectory groups were identified; No LTSA (74%), Decreasing (18%), and Increasing (8%). Compared to the No LTSA trajectory, employees in the Decreasing trajectory were more likely to have chronic (OR 1.34, 95% CI 1.04-1.73) or multisite (OR 1.81, 95% CI 1.36-2.41) pain, smoke (OR 1.55, 95% CI 1.18-2.03), have obesity (OR 1.70, 95% CI 1.21-2.38), manual or routine non-manual occupation (OR 1.87, 95% CI 1.31-2.67) and high physical workload (OR 1.47, 95% CI 1.14-1.90), after adjusting for age and gender. Predictors of the Increasing trajectory were not identified. Conclusions Distinct LTSA-trajectories were identified among young and early midlife employees with pain, of whom a majority had no LTSA during follow-up. Chronic and multisite pain, unhealthy lifestyle, lower occupational class, and higher physical workload are related to a pattern with more LTSA. Future intervention studies could examine opportunities to prevent LTSA through supporting younger employees who work with pain and have these risk factors. Key messages • Distinct trajectories of LTSA were identified among younger employees with pain, of whom most had no LTSA. Pain characteristics, lifestyle and occupational factors predicted trajectory membership. • Future intervention studies could examine opportunities to prevent LTSA through support to employees who work with pain and have pain-, lifestyle- and occupation related risk factors of LTSA.

Medical students’ attitude toward patient-centeredness: A longitudinal study

ObjectivesThis study explored the trajectories of patient-centered orientation in a sample of Italian medical students throughout medical school. MethodsFour consecutive student cohorts were longitudinally assessed at the second (T0) and fifth year (T1) of medical school. Students completed a questionnaire including demographics and the Italian validated version of the Patient-Practitioner Orientation Scale. Results352 students completed both administrations. Students became more patient-centered in terms of Sharing along the course of their clinical curriculum, whereas there were no significant changes in Caring. Groups with distinct developmental trajectory patterns of both Caring and Sharing were identified. Students high in patient-centeredness at T0 reported significantly lower scores at T1 while students with lower scores at T0 significantly increased from the first to the last measurement. Female students significantly outscored their male colleagues on Caring and Sharing in both administrations. ConclusionsFindings call for innovative education strategies to sustain patient-centeredness attitudes in medical students entering hospital-based clinical medicine. Further research is needed to identify characteristics of the medical curriculum that are primarily involved in fostering students’ patient-centeredness. Practice ImplicationsIncluding the assessment and monitoring of patient-centeredness throughout the medical school can inform tailored education aiming to foster this dimension.

Evaluation of Supply and Demand Balance and Spatial Spillover Effect of Age-Friendly Environment

Given the rapid development of population aging, regions face significant challenges in providing diverse public service resources for the elderly. Constructing an age-friendly environment actively addresses population aging and ensures the well-being of the elderly. This study employed panel data from 31 provinces (municipalities) in China spanning the years 2014 to 2020. The research utilized a coupling coordination degree model, Theil index, Moran index method, and spatial econometric model to empirically examine the level of coupling coordination development, regional differences, and spatial spillover effects of age-friendly environments. The findings indicate the following: (1) In terms of coupling and coordination development, the degree of coupling and coordination of age-friendly environments in China shows a consistent upward trend over the years. The eastern region exhibits the highest level of development, surpassing the national average, while the western region has the lowest level, followed by the northeast and central regions. (2) In terms of regional development disparities, inter-regional differences gradually intensify due to variations in development status and resource endowment, playing a significant role in overall variations. Within regions, the highest intra-regional differences occur in the eastern region, while the lowest occur in the western region. (3) Considering the spatial spillover effect, the coupling coordination degree of age-friendly environments demonstrates positive spatial autocorrelation. Various development clusters and variables exert diverse influences on the coupling coordination degree of age-friendly environments within the region, while the spatial spillover effect of surrounding regions manifests distinct development patterns. The findings of this study contribute to enhancing the quality of age-friendly environment construction and promoting coordinated development among different regions.

Longitudinal Stability and Interrelations of Tonic and Phasic Irritability in Adolescent Girls.

Irritability is a transdiagnostic feature and a common mental health problem in adolescence. Prior studies indicate that irritability is composed of two correlated but separable dimensions, tonic irritability (i.e., irritable mood) and phasic irritability (i.e., temper outbursts), which are respectively associated with internalizing and externalizing outcomes. However, little is known about the stability and interrelations of tonic and phasic irritability. The current study examined the longitudinal interplay between tonic and phasic irritability during adolescence. A community sample of 544 girls (age 13.5-15.5 years) was assessed at 5 waves (over 3 years, in 9-month intervals). A random-intercept cross-lagged panel model was used to examine the within-person stability and longitudinal interrelations of tonic and phasic irritability. Pseudo-indicator models were used to help analyze all available data. Results suggest that tonic and phasic irritability had distinct patterns of development and co-development. Between individuals, tonic and phasic irritability showed moderate rank-order stability and high concurrent correlations. Within individuals, phasic irritability was found to positively predict both tonic and phasic irritability at the subsequent wave, whereas tonic irritability did not predict later phasic irritability and showed weaker within-person stability. These results suggest that increased or decreased phasic irritability in adolescent girls may signify continued increase or decrease in both tonic and phasic irritability. The study was among the first to demonstrate the discriminant validity of tonic and phasic irritability from a developmental perspective.