Stress-related changes in personality: A longitudinal study of perceived stress and trait pessimism

•Personality can change over time but the determinants of such change remain unclear.•To address this, we examined relations between stress and pessimism over five weeks.•Perceived stress and pessimism both decreased over the five-week study period.•In two of the three models tested, changes in stress predicted changes in pessimism.•These data are thus the first to show that stress predicts changes in personality.

Although research has shown that certain aspects of personality can change over time, the determinants of such change remain unclear. Stress alters neural dynamics and precipitates disorders that shape personality traits involving negative affectivity. In this study, therefore, we assessed the perceived stress and pessimism levels of 332 young, middle-aged, and older adults for five weeks to examine how levels of stress and pessimism change and interrelate over time. The best fitting longitudinal model was a bivariate latent growth curve model, which indicated that stress and pessimism both changed and exhibited significant variability in change over time. Moreover, changes in stress were associated with changes in pessimism. Pessimism thus changes over time, with alterations in stress potentially structuring these changes.