Neural correlates of prospective memory in Parkinson’s disease: a high-density EEG study

Introduction: Prospective memory (PM), the ability to remember and execute intended actions in the future, is a critical component of daily functioning and independent living, particularly in individuals with Parkinson's disease (PD). Although PM deficits in PD have been widely documented, their underlying neural mechanisms remain poorly understood. Methods: This study addresses this gap by being the first to investigate the neurophysiological signatures of PM in a sample of 28 PD patients without mild cognitive impairment (MCI) and 34 matched healthy controls using high-density electroencephalography (hd-EEG). Participants completed naturalistic event-based and time-based PM tasks while monitoring virtual cooking activities embedded in a movie presented on a smart TV, with concurrent neurophysiological recording. Results: Behavioral performance did not differ between groups in either PM task, likely reflecting preserved global cognition in the PD sample; however, EEG analyses revealed marked oscillatory differences. During time-based PM tasks, PD patients exhibited increased theta, alpha, and beta power, suggesting greater engagement of internal attention monitoring and proactive control mechanisms. Conversely, during event-based PM tasks, PD patients showed reduced power in these frequency bands, consistent with a shift toward externally driven attention to monitor the occurrence of the PM event. Discussion: This pattern of findings can be interpreted within the framework of the Attention to Delayed Intention (AtoDI) model. Overall, the present study demonstrates that electrophysiological measures can detect subtle neural alterations in the absence of overt behavioral impairments and can reveal compensatory mechanisms adopted by PD patients to cope with PM demands.