Kinoshita, RinkoYu, ChunyanAhmed, Saifuddin2026-09-112026-09-112026Yu, C., Ahmed, S., Li, M., Zuo, X., Fine, S.L., Hunersen, K., Borges, A.L.V., Kinoshita, R., Mafuta, E.M., Pinandari, A.W. and Wilopo, S.A., 2026. Reliability and Validity of Early Adolescent Mental Health Scale: An Analysis of Cross-Sectional and Longitudinal Data of the Global Early Adolescent Study. JAACAP Open.https://doi.org/10.1016/j.jaacop.2026.05.004https://hdl.handle.net/10566/25409Objective: Assessment of mental health problems among young adolescents remains challenging because of a scarcity of suitable measurement tools. A 6-item questionnaire, the Early Adolescent Mental Health Scale (EAMHS), was designed to measure the mental health of young adolescents in urban, low-resource settings and was used in the Global Early Adolescent Study (GEAS). This study aims to assess the reliability and validity of the EAMHS. Method: Through a secondary data analysis of cross-sectional and longitudinal datasets from the GEAS, we first refined the underlying constructs of the EAMHS using exploratory factor analysis and assessed its internal reliability. We then took a set of measurement invariance tests to verify the cross-group, cross-cultural, and cross–time-point validity of the refined scale. Subsequently, we conducted a hypothesis test of construct validity and responsiveness using linear regression, incorporating adjustments for the complex sampling design. We carried out calibration between the EAMHS and the Patient Health Questionnaire—4 (PHQ-4) through a single-group design kernel equipercentile equating method, and obtained suggested cut-off scores at each site based on the first follow-up (T2) data. The discriminative ability of the scale with suggested cut-offs was assessed against the adolescents’ PHQ-4 scores of 6 or higher at the second follow-up (T3) using receiver operating characteristic (ROC) curve analyses. Results: The initial 6-item EAMHS was reduced to a 4-item version of a unidimensional structure. Scalar invariance was achieved across genders, age groups, and cultures in longitudinal datasets of 5 study sites. The 4-item EAMHS demonstrated acceptable internal reliability and structural validity, as well as excellent construct validity relative to that of the PHQ-4. Suggested EAMHS cut-off scores showed fair to good discriminative ability in the subsequent follow-up round, with area under the curve (AUC) values ranging from 0.71 (95% CI = 0.64-0.74) in Kinshasa to 0.82 (95% CI = 0.77-0.87) in Shanghai. Conclusion: The findings verified the EAMHS as a consistent and accurate measure, supporting its use for monitoring and evaluating general emotional disturbance within the study context. Diversity & Inclusion Statement: We worked to ensure sex and gender balance in the recruitment of human participants. We worked to ensure that the study questionnaires were prepared in an inclusive way.encalibrationEarly Adolescent Mental Health Scalemeasurement invariancereliabilityvalidityArticle