The theoretical foundation of the collection is life course theory, which holds that development unfolds through a series of life transitions marking periods of growth and change. Building on Erik Erikson’s account of the life cycle, each life stage involves a developmental task whose resolution enables the transition to the next. Crucially, the editors emphasise that stress is not inherently harmful. Some stress can stimulate growth, foster resilience, and prompt healthy shifts in behavioural or social roles. But exposure to unpredictable or severe stressors can bend developmental trajectories in lasting ways, and it is precisely this distinction that longitudinal designs are uniquely positioned to capture. By following the same individuals across multiple waves of assessment, researchers can separate the effects of stage-specific stress from the effects of chronic adversity, and can identify which early signals predict which later outcomes.

The earliest contributions focus on early childhood and the transition to school. A randomised controlled trial of Brazil’s Happy Child Program, a national initiative designed to promote healthy development to age six by addressing parenting behaviours, followed 284 children and families across three assessments. The findings were strikingly practical: maternal growth monitoring and non-violent discipline were linked to positive child outcomes, while older maternal age and psychological aggression predicted poorer ones. In a separate study of 94 children aged two to five with intellectual disabilities, researchers used hospital record data to track developmental quotients, a measure of progress against age norms. Cross-lagged panel modelling across three waves showed that early adaptive behaviour predicted later language and personal-social development, supporting the prioritisation of adaptive skills in early intervention. Meanwhile, a cohort study of young Canadian children examined five kindergarten developmental domains — physical health, social competence, emotional maturity, language, and communication — and found that of 23 predictors spanning prenatal exposures to family stress, childhood family stress at ages one and three and lower socioeconomic status predicted poorer outcomes, while prenatal maternal and postnatal child health did not.

Adolescence brings its own stressors, including increasing choice and control over diet. In a longitudinal survey of 1,693 Chinese students aged 12 to 16 years, researchers examined adolescent eating patterns and depressive symptoms. Skipping or irregular breakfast consumption and late-night snacking were significantly associated with higher levels of depressive symptoms over the course of the study, adding to growing evidence that diet plays an important role in adolescent development, including mental health. The collection also addresses hospitalization, one potentially critical outcome for young people experiencing mental health disorders. Aiming to improve the transition from inpatient to outpatient care, a mixed-methods study protocol for the ReCoVer Study will examine the role of the family environment in post-discharge outcomes following psychiatric inpatient care, following caregivers during the first six months after discharge to investigate caregiver burden and family influences on recovery.

Measurement of serious mental illness in young people is another focus. Using longitudinal data from over 3,000 young people aged 15 to 24 years in Hong Kong, researchers confirmed a three-factor model of schizotypy, a mental health condition characterised by interpersonal deficits and related behaviour that creates difficulty for individual functioning. The behaviour associated with schizotypy was strongly related to psychotic-like experiences, social anxiety, and personality traits, highlighting the potential value of schizotypy assessment for identifying and supporting young people in the early stages of serious mental illness. In a separate study of 125 young people aged 6 to 13 years, 56 of whom had an ADHD diagnosis, researchers compared self-report questionnaires, attention performance tests, and reports from parents and teachers. Parent and teacher questionnaires had the highest classification accuracy in identifying inattentive symptoms, while objective attention tests were less effective, underlining the importance of multi-informant assessment for the diagnosis of ADHD in young people.

The collection also moves from mental to physical health. A longitudinal study of 60 Chinese children and adolescents aged 8 to 18 years with leukemia examined post-traumatic growth and coping styles over three waves of data tracking from remission to maintenance therapy. Positive coping styles were associated with greater post-traumatic growth, though gains levelled off over time, while negative coping in the form of emotional reactivity was associated with lower growth. The findings suggest that the assessment of coping styles and growth may support patients’ wellbeing and improve outcomes among children and adolescents undergoing treatment for leukemia. The transition to university is another important period for many young people. Researchers followed 761 first-year students aged 17 to 19 years over three waves to examine reciprocal associations between measures of depression and social support taken at three intervals. Simultaneous daily diary data provided additional evidence that this effect occurs at the daily level, with depression associated with decreased support the following day, and vice versa, indicating that interventions addressing both factors may reduce depression and improve adjustment during the first year of university.

The Covid-19 pandemic generated extensive research into the stress caused by disrupted education, work and family life, and several articles in the collection examine this unusual stressor. In a cohort of parents and young people, researchers analysed household chaos and youth emotional wellbeing at three points during the pandemic. Higher levels of perceived household chaos were associated with increasing behavioural problems, sleep disturbances, anxiety and emotional dysregulation. Older children’s perceptions of household chaos tended to differ from their parents’ view, unlike younger children, suggesting that family dynamics play an important role in buffering unusual stressors and may represent an important target for interventions.

Two further articles examine how prior adversity shaped mental health under pandemic stress. Among 171 young adults with a mean age of 22 years, researchers examined how adverse childhood experiences shaped mental health across pre-, peak-, and post-peak pandemic periods. Higher ACE exposure predicted poorer mental health under high pandemic stress and slower improvement over time, reinforcing that adverse childhood experiences heighten vulnerability to later mental health problems under significant stress. In Australia, where pandemic restrictions were exceptionally prolonged, researchers examined parental substance use among 560 parents. Prior substance use predicted continued use during the pandemic, and poorer parent-infant bonding was linked to a greater likelihood of alcohol, tobacco and drug use, highlighting family systems as a target for reducing substance use during major stressors.

Together, the twelve articles showcase the depth of contemporary life course research, spanning diverse questions, methods and analytic approaches to stress and adaptation. They demonstrate both the close interrelation of life transitions and stress, and the capacity of longitudinal studies to disentangle these dynamics. The editors argue that this evidence base can inform interventions that promote resilience and adaptive functioning across the lifespan, from parenting programmes in early childhood to family-based support during hospital discharge and beyond. As the collection makes clear, the transitions of childhood and adolescence are not merely passages to be survived but opportunities to be shaped, and the timing and nature of the stress young people encounter can determine whether those transitions foster growth or leave lasting scars.

Subject of Research: Longitudinal data analysis in child and adolescent mental health, volume II

Article Title: Editorial: Longitudinal data analysis in child and adolescent mental health, volume II

Article References: Boden, J. M., Zheng, S., Kerr, J. A., & Hirota, T. (2026). Editorial: Longitudinal data analysis in child and adolescent mental health, volume II. Frontiers in Child and Adolescent Psychiatry, 5, Article 1979900. https://doi.org/10.3389/frcha.2026.1979900

Image Credits: AI Generated

DOI: 10.3389/frcha.2026.1979900

Keywords: longitudinal studies, child and adolescent mental health, life course theory, Covid-19 pandemic, developmental psychopathology, life stress, Editorial, Longitudinal, data, analysis, child, adolescent