Systematic Review and Meta-Analysis: Early Irritability as a Transdiagnostic Neurodevelopmental Vulnerability to Later Mental Health Problems.

OBJECTIVE: Irritability is a transdiagnostic indicator of child and adolescent internalizing and externalizing problems that is measurable from early life. The objective of this systematic review was to determine the strength of the association between irritability measured from 0 to 5 years and later internalizing and externalizing problems, to identify mediators and moderators of these relationships, and to explore whether the strength of the association varied according to irritability operationalization. METHOD: Relevant studies published in peer-reviewed, English-language journals between the years 2000 and 2021 were sought from EMBASE, PsycINFO, MEDLINE, CINAHL, and ERIC. We synthesized studies that included a measure of irritability within the first 5 years of life and reported associations with later internalizing and/or externalizing problems. Methodological quality was assessed using the JBI-SUMARI Critical Appraisal Checklist. RESULTS: Of 29,818 identified studies, 98 met inclusion criteria, with a total number of 932,229 participants. Meta-analysis was conducted on 70 studies (n = 831,913). Small, pooled associations were observed between infant irritability (0-12 months) and later internalizing (r = 0.14, 95% CI = 0.09, 0.20) and externalizing symptoms (r = 0.16, 95% CI = 0.11, 0.21) symptoms. For toddler/preschool irritability (13-60 months), small-to-moderate pooled associations were observed for internalizing (r = 0.21, 95% CI = 0.14, 0.28) and externalizing (r = 0.24, 95% CI = 0.18, 0.29) symptoms. These associations were not moderated by the lag between irritability and outcome assessment, although the strength of the associations varied according to irritability operationalization. CONCLUSION: Early irritability is a consistent transdiagnostic predictor of internalizing and externalizing symptoms in childhood and adolescence. More work is required to understand how to accurately characterize irritability across this developmental period, and to understand mechanisms underlying the relationship between early irritability and later mental health problems. DIVERSITY & INCLUSION STATEMENT: One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as living with a disability. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group. STUDY PREREGISTRATION INFORMATION: Early irritability as a transdiagnostic neurodevelopmental vulnerability to early onset mental health problems: A systematic review; https://www.crd.york.ac.uk/prospero/; CRD42020214658.

Caregiver-mediated interventions to support self-regulation among infants and young children (0-5 years): a protocol for a realist review.

INTRODUCTION: Self-regulation is a modifiable protective factor for lifespan mental and physical health outcomes. Early caregiver-mediated interventions to promote infant and child regulatory outcomes prevent long-term developmental, emotional and behavioural difficulties and improve outcomes such as school readiness, educational achievement and economic success. To harness the population health promise of these programmes, there is a need for more nuanced understanding of the impact of these interventions. The aim of this realist review is to understand how, why, under which circumstances and for whom, early caregiver-mediated interventions improve infant and child self-regulation. The research questions guiding this review were based on consultation with families and community organisations that provide early childhood and family services. METHODS AND ANALYSIS: Realist reviews take a theory-driven and iterative approach to evidence synthesis, structured around continuous refinement of a programme theory. Programme theories specify context-mechanism-outcome configurations to explain what works, for whom, under which circumstances and how. Our initial programme theory is based on prior work in this field and will be refined through the review process. A working group, comprising service users, community organisation representatives, representatives from specific populations, clinicians and review team members will guide the evidence synthesis and interpretation, as well as the development and dissemination of recommendations based on the findings of the review. The review will involve searching: (i) electronic databases, (ii) connected papers, articles and citations and (iii) grey literature. Decisions to include evidence will be guided by judgements about their contribution to the programme theory and will be made by the research team, with input from the working group. Evidence synthesis will be reported using the Realist and MEta-narrative Evidence Synthesis: Evolving Standards guidelines. ETHICS AND DISSEMINATION: Ethical approval is not required as this is a review. Findings will be disseminated to our working group and through peer-reviewed publications and conference presentations. REVIEW REGISTRATION NUMBER: The protocol is registered with Open Science Framework https://osf.io/5ce2z/registrations.