Characterizing Within-Person Trajectories of Negative Affect Across Adolescence: A Longitudinal Clustering Approach.

While day-to-day negative affect normatively rises across adolescence, emotional experiences also stratify, or diverge, across individuals. Moreover, negative affect is not a unitary construct but comprises distinct feeling states (e.g., sadness, anger, anxiety), each characterized by distinct age-related trends. Yet, most developmental research relies on cross-sectional approaches and treats negative affect as a singular dimension, limiting insights into the granular, within-person trajectories of discrete negative affects across adolescence. In the current study, we aimed to characterize these trajectories using a three-wave longitudinal sample (spanning ∼2.5 years, N = 251, aged 9-15 years at baseline) from the Human Connectome Project in Development for analysis. At each visit, participants completed self-report measures assessing different forms of negative affect-sadness, anger, evaluative anxiety, and general anxiety-and a range of social and global functional outcomes. Analyses revealed three distinct subgroups of adolescents-one whose daily negative affect was low and rose only modestly with age, one whose daily negative affect was moderate and rose more significantly with age, and one whose daily negative affect started high and continued to intensify with age. These clusters meaningfully differentiated on external functional outcome measures of social functioning and life satisfaction. Additionally, regression analyses revealed that slopes for specific negative affect types provided unique predictive value for certain outcomes, emphasizing the importance of preserving affective granularity in investigations of adolescent emotional experience. These findings help to refine theories of adolescent emotional development by revealing the specific negative affect trajectory patterns and discrete affect types most predictive of subsequent well-being. SUMMARY: We used a longitudinal clustering approach to characterize within-person trajectories of negative affective experiences in individuals 9-15 years at baseline. While on average, negative affect increases across adolescence, there is a large degree of variability between individuals across this period of life, motivating an investigation of its underlying structure. Finite mixture models revealed three latent subgroups of individuals differing both in the intensity and developmental trajectories of negative affect and that differentiated on functional outcome measures. Findings enhance the granularity in describing typical age-related affect trajectories and highlight subgroups of individuals at a higher risk of experiencing poorer well-being.