(PS5-5) Intraindividual Dynamics Between Rumination and Irritability in Adults

Irritability is a transdiagnostic symptom prevalent in many psychiatric illnesses characterized by a multifaceted nature, including phasic and tonic forms. Tonic irritability refers to a chronic irritable mood, while phasic irritability exhibits episodic aggressive outbursts. Few studies have differentiated the tonic and phasic aspects of irritability among adults and none examined the role of rumination. 

Rumination, a repetitive and passive focus on one's distress, is a prevalent psychological process underlying mood impairment. Previous research has explored the association between irritability and rumination, reflecting a mutual reinforcement relationship. However, a significant gap remains in understanding the specific relationships between phasic and tonic irritability and rumination. Additionally, most existing evaluation data are derived from cross-sectional studies, which lack the dynamic nature of irritability over time. Our current study applies a multivariate multilevel modeling approach to examine intraindividual dynamics of tonic and phasic irritability. Additionally, we investigate the role of daily rumination in phasic and tonic irritability among adults.

The current study includes 98 online adults who endorsed depressed mood and anhedonia in the past two weeks. We used multivariate linear mixed effects models to examine the bivariate intraindividual covariation (1) between rumination and phasic irritability, and (2) between rumination and tonic irritability.

We found the positive autoregressive intraindividual effects of rumination (p < 0.001) and phasic irritability (p < 0.001) but not tonic irritability (p =0.0674). Engagement in rumination in the past day predicted increased rumination the following day (p< 0.01). Notably, past-day rumination is only significant in predicting tonic irritability (p=0.0210) but not phasic irritability. Neither past day tonic (p=0.0810) or phasic irritability (p=0.6073) predicted rumination.

This study provides us with a nuanced understanding of the dynamics between daily brooding rumination and its relation to tonic and phasic irritability. Our findings highlight potentially differential cognitive bases underlying tonic and phasic irritability in adults.