Longitudinal studies of child mental disorders in the general population: A systematic review of study characteristics

INTRODUCTION: Longitudinal studies of child mental disorders in the general population (herein study) investigate trends in prevalence, incidence, risk/protective factors, and sequelae for disorders. They are time and resource intensive but offer life‐course perspectives and examination of causal mechanisms. Comprehensive syntheses of the methods of existing studies will provide an understanding of studies conducted to date, inventory studies, and inform the planning of new longitudinal studies. METHODS: A systematic review of the research literature in MEDLINE, EMBASE, and PsycINFO was conducted in December 2022 for longitudinal studies of child mental disorders in the general population. Records were grouped by study and assessed for eligibility. Data were extracted from one of four sources: a record reporting study methodology, a record documenting child mental disorder prevalence, study websites, or user guides. Narrative and tabular syntheses of the scope and design features of studies were generated. RESULTS: There were 18,133 unique records for 487 studies—159 of these were eligible for inclusion. Studies occurred from 1934 to 2019 worldwide, with data collection across 1 to 68 time points, with 70% of studies ongoing. Baseline sample sizes ranged from n = 151 to 64,136. Studies were most frequently conducted in the United States and at the city/town level. Internalizing disorders and disruptive, impulse control, and conduct disorders were the most frequently assessed mental disorders. Of studies reporting methods of disorder assessment, almost all used measurement scales. Individual, familial and environmental risk and protective factors and sequelae were examined. CONCLUSIONS: These results summarize characteristics of existing longitudinal studies of child mental disorders in the general population, provide an understanding of studies conducted to date, encourage comprehensive and consistent reporting of study methodology to facilitate meta‐analytic syntheses of longitudinal evidence, and offer recommendations and suggestions for the design of future studies. Registration DOI: 10.17605/OSF.IO/73HSW.