Personality trait and state associations with cognitive functioning and variability in middle-aged and older adults

OBJECTIVES: Personality characteristics are recognized as early indicators of later cognitive functioning, yet existing studies have primarily focused on trait-level trends. How well these between-person differences uncover daily cognitive functioning processes remains unclear. Addressing this entails examining momentary personality states, which may accumulate over time to influence longer-term cognitive outcomes. Accordingly, this study investigates associations between personality traits and states and momentary cognitive functioning and variability. METHODS: We conducted a three-week ecological momentary assessment study of middle-aged and older adults (N = 183). We used Bayesian Mixed-Effects Location Scale Models to capture contingencies between personality and momentary cognitive functioning/variability. Additionally, we used machine learning (elastic net regression) to identify profiles of personality state-cognition contingencies and individuals who exhibit stronger associations. RESULTS: At the trait level, higher conscientiousness was associated with poorer working memory and processing speed. Higher openness was associated with better cognitive functioning and lower variability for episodic memory and processing speed. At the state level, conscientiousness was associated with better working memory performance, while neuroticism was associated with variable episodic memory functioning. Extraversion was associated with working and episodic memory functioning/variability. Finally, sociodemographic, health, and personality trait variables emerged as top predictors of individual differences in within-person associations. DISCUSSION: By investigating within-person associations between personality and cognitive ability, we demonstrate that trait-level associations do not necessarily generalize to state-level ones. Profiles of top predictors of individual differences in state-level associations may be promising targets for intervention, but interventions should be tailored with between- and within-person differences in mind.