Examining the clinical potential of the concurrent EEG aperiodic exponent in cognitive testing.

Introduction: An important frontier for neuropsychology involves developing additional technologies that could complement current behavioral approaches. Concurrent electroencephalographic (EEG) markers are especially promising for informing the neural processes underlying cognitive performance during neuropsychological assessments. The EEG aperiodic exponent shows sensitivity to both age and task-related effects, with prior studies relating smaller exponents to poorer performance in older adults, and larger exponents to greater task engagement in general. This study aimed to extend these previous experimental findings on the aperiodic exponent to a standardized assessment context and begin clarifying its relations to clinically meaningful aspects of cognition and aging.

Method: EEG was recorded during resting conditions and administration of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) from 21 younger adults and 24 older adults. Two-level mixed-effects regression models were run to assess the effects of age, general cognitive task engagement (vs. rest), and cognitive domain (Index) on the exponent.

Results: Consistent with prior studies, exponents were generally larger during cognitive tasks compared to rest (F(2,81.76) = 61.54,  < .001) and in younger versus older adults (F(1,42.37) = 26.80,  < .001). Moreover, compared to younger adults, older adults' exponents exhibited greater sensitivity to cognitive domain (Age ×Index interaction: F(5,206.93) = 9.51,  < .001).

Conclusions: Results suggest that key effects of the exponent (i.e. age and task) can be reproduced during realistic assessment scenarios, and suggest the exponent is more sensitive to between-person and age group differences than task effects. Additional investigations are needed to clarify the potential of the concurrent exponent to capture clinically meaningful cognitive processes.