Repetitive Negative Thinking in Daily Life: Temporal Dynamics and Transdiagnostic Associations with Mental Health Across Adulthood

Repetitive negative thinking (RNT) is a transdiagnostic process implicated in a wide range of psychological disorders. Ecological momentary assessment (EMA) provides a valuable approach to capture the temporal dynamics of RNT in daily life, while minimizing retrospective biases and reliance on metacognitive beliefs. However, EMA-based assessments of RNT have not yet been systematically evaluated in large, age-diverse samples, limiting our understanding of their latent structure, construct validity, temporal dynamics, lifespan variation, and associations with mental health. To address these gaps, 4,826 adults aged 18–100 years completed EMA surveys of momentary thoughts and mood via smartphone. Using a split-half approach, multilevel exploratory factor analysis identified a 2-within/1-between factor structure, which was subsequently replicated in an independent confirmatory sample. Across both samples, the within-person factor 1 (WF1)—reflecting momentary thought characterized by more negative content, greater unintentionality, increased task-unrelatedness, heightened attentional focus on thoughts, and greater abstractness—captured an RNT-related dimension of momentary thought. This was evidenced by convergent validity through associations with trait RNT and cross-lagged temporal associations with momentary mood, as well as criterion-related validity through associations with mental health indicators, including general psychological distress, depression, anxiety, and loneliness. Analyses of dynamic parameters further indicated that greater variability and instability in WF1 scores were associated with poorer mental health. Higher age was associated with lower levels of EMA-based RNT-related thought, and RNT-related thought statistically accounted for a portion of the cross-sectional association between age and mental health outcomes. Together, these findings support the psychometric validity of an EMA-based assessment of RNT-related momentary thought and highlight systematic age differences in RNT-related experiences in daily life.