Alpha Band EEG Dynamics During Naturalistic Storytelling Interaction in Older Adult Caregiver Dyads

Naturalistic social interaction provides an important context for examining how cognitive engagement is reflected in brain activity, yet electroencephalographic evidence from older adult caregiver interaction remains limited. This study examined alpha band EEG dynamics during museum-based storytelling interaction in older adult caregiver dyads. Thirty two dyads, comprising 32 older adults and 32 caregivers, completed cognitive and psychological screening and underwent EEG recording during eyes-closed resting, eyes open resting, storytelling, and listening conditions. Relative alpha power was analyzed using a predefined 10-electrode sensor-level set covering frontal, frontotemporal, temporal, central, and parietal midline regions. Task-related alpha modulation was examined relative to eyes-open resting. Associations between cognitive performance and Cz alpha power were tested using MoCA scores, and dyad level alpha band inter-brain similarity was examined using spatial alpha-power patterns with within site shuffled dyad surrogate comparisons. Alpha power was higher during eyes closed resting and lower during storytelling and listening relative to eyes-open resting, indicating robust task-related modulation of alpha activity during naturalistic narrative interaction. Associations between MoCA scores and Cz alpha power were weak, condition specific, and did not survive false discovery rate correction. During storytelling, dyad level alpha band inter brain similarity was modestly higher than within site shuffled dyad estimates, but this effect did not remain significant after correction across conditions. These findings suggest that alpha band EEG activity is sensitive to naturalistic storytelling and listening in older adult caregiver dyads. However, cognitive associations and dyad level inter brain similarity were modest and should be interpreted cautiously. The study demonstrates the feasibility of applying EEG to real world social cognitive interaction while highlighting the need for larger samples, behavioral coding, and time resolved dyadic EEG methods to clarify mechanisms of interpersonal neural coordination.