Resting-State EEG Aperiodic Activity and Negative Affective Vulnerability: The Mediating Role of Big Five Personality...

Resting-state EEG aperiodic parameters characterize the broadband background component of neural activity. The offset reflects overall broadband power and has been linked to population-level firing, whereas the exponent is often interpreted, within a theoretical framework, as an indirect proxy for cortical excitation/inhibition (E/I) balance. These measures may therefore provide candidate neurophysiological trait markers of negative affective vulnerability, but it remains unclear whether their associations with trait anxiety and trait depression are direct or are statistically accounted for by stable personality traits.

A total of 164 healthy adults completed measures of the Big Five personality traits, trait anxiety, and trait depression and underwent eyes-closed resting-state EEG recording. Aperiodic exponent and offset were estimated at the whole-brain and regional levels using spectral parameterization. Partial correlations, hierarchical regression analyses, and bootstrap mediation analyses were conducted controlling for sex, age, and years of education.

Neuroticism showed the strongest and most spatially widespread positive associations with the aperiodic exponent. Trait anxiety showed more limited associations, mainly with whole-brain and frontal aperiodic parameters. The association between whole-brain exponent and trait anxiety was no longer significant after the Big Five personality traits were entered into the model. Bootstrap mediation analyses identified significant indirect effects in this association through personality traits, with neuroticism showing the largest indirect effect and conscientiousness also showing a significant indirect effect. Trait depression was not directly associated with aperiodic parameters, although significant indirect effects through personality traits were observed.

Resting-state EEG aperiodic activity, particularly the exponent, was more consistently associated with stable personality dispositions than with negative affective vulnerability directly. Personality traits, especially neuroticism, may statistically account for part of the association between aperiodic exponent and trait anxiety. Because the data were cross-sectional, the temporal and causal direction of these associations cannot be determined.