1\. ABOUT THE DATASET ------------ Title: Data supporting: "Anhedonia mediates the relationship between stigma and Major Depressive Disorder (MDD): A longitudinal path analysis" Creator(s): Katie Prizeman (katiediab@gmail.com), ORCiD https://orcid.org/0000-0003-3960-6467 Organisation(s): Department of Psychology and Clinical Language Sciences, University of Reading, Reading, United Kingdom Rights-holder(s): Katie Prizeman Publication Year: 2025 Description: Major Depressive Disorder (MDD) is one of the most common mental health conditions affecting young people and is linked to major impairments in functioning, quality of life, and suicide risk. Adolescence and emerging adulthood are particularly vulnerable periods due to ongoing brain and social development, making young people more sensitive to stress and stigma. Internalised stigma is a key psychosocial stressor that can intensify MDD symptoms, yet the mechanisms explaining this link remain poorly understood and have rarely been tested in clinically depressed youth. Data was collected from young people aged 16–25 years with clinically significant MDD symptoms (Mood and Feelings Questionnaire (MFQ)) who completed measures of MDD (MFQ), anhedonia (Anhedonia Scale for Adolescents (ASA)), and stigma (Internalized Stigma of Mental Illness Inventory-9 (ISMI-9*)) at baseline (N = 445) and six-month follow-up (N = 343). The study investigated whether anhedonia mediates the relationship between stigma and MDD symptoms, both cross-sectionally and longitudinally. By combining validated clinical measures with a longitudinal design, this dataset provides a rare opportunity to examine how stigma contributes to the persistence and worsening of MDD in youth. This is the first study to demonstrate that anhedonia is a central mechanism linking stigma to MDD over time, advancing theoretical understanding, highlighting a novel intervention target, and informing the development of stigma-reduction and early intervention strategies for young people. The dataset includes participants’ demographic information alongside responses to questionnaires assessing MDD symptoms, stigma, and anhedonia, at both baseline and follow-up. Cite as: Prizeman, Katie (2025): Data supporting: "Anhedonia mediates the relationship between stigma and Major Depressive Disorder (MDD): A longitudinal path analysis". University of Reading. Dataset. https://researchdata.reading.ac.uk/id/eprint/1462 Related publication: • Title: Anhedonia mediates the relationship between stigma and Major Depressive Disorder (MDD): A longitudinal path analysis • Corresponding author: Katie Prizeman • Co-authors: Sena Demir-Kassem & Ciara McCabe • Journal: TBD • Current status: Manuscript to be submitted • Expected date of publication: N/A Contact: Katie Prizeman (katiediab@gmail.com) Acknowledgements: We would like to thank all the participants who volunteered their time to support this study. Their involvement was crucial to the success of the research, and we greatly appreciate their contributions. 2\. TERMS OF USE ------------ Copyright 2025 Katie Prizeman. This dataset is licenced under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3\. PROJECT AND FUNDING INFORMATION ------------ This project received no other funding. This dataset was not created in the course of a funded project. 4\. CONTENTS ------------ File listing 1. Data\_File\_Prizeman\_2025 Includes 1 excel file made up of 1 excel sheet: • Sheet 1: Contains all participant socio-demographic and study data, including age, country of residence, ethnicity, and gender. In addition, it includes participants’ raw total scores on the Anhedonia Scale for Adolescents (ASA), Internalized Stigma of Mental Illness Inventory (ISMI-9*), and Mood and Feelings Questionnaire (MFQ) at both baseline and again at six-month follow-up. 5\. METHODS ----------- Data for this study were collected specifically for research purposes and are publicly available in de-identified form via the University of Reading’s Research Data Archive. Ethical approval was obtained from the University of Reading’s Research Ethics Committee (REC: 2022-072-NW), and all procedures adhered to institutional guidelines and the Helsinki Declaration. Participants provided written informed consent, were debriefed with access to support resources, and could opt into future research contact. A total of 445 young people aged 16–25 years (M = 20.74, SD = 2.31) with clinically significant depressive symptoms (MFQ ≥ 27) were recruited via university counselling services, primary care, online advertisements, and community organisations. Exclusion criteria included psychotic, bipolar, or primary anxiety disorders, and current substance dependence. Participants completed baseline measures online via secure surveys and were reimbursed with entries into Amazon voucher prize draws; 343 participants (77%) completed six-month follow-up measures. Sample size exceeded thresholds derived from power analyses, ensuring sufficient power to detect medium-sized mediation effects. Depression symptoms were assessed using the 33-item MFQ, anhedonia with the 14-item ASA, and stigma with the 9-item ISMI-9*. All measures demonstrated strong psychometric properties, including high internal consistency and reliability. Participants completed baseline assessments in a single online session with opportunities to ask questions beforehand. The study employed a mixed cross-sectional and longitudinal design, allowing examination of relationships between internalized stigma, anhedonia, and depressive symptoms over time, while maintaining ecological validity by including participants with co-occurring anxiety symptoms who did not report a primary anxiety disorder.