Frontiers in Systems Neuroscience · May 26, 2026

A novel 1-channel EEG marker may associate with perioperative cognitive change

By Baron Shahaf D, Bolotin G, Cohen O et al.

INTRODUCTION: Postoperative cognitive decline, at least transiently, is considered a prevalent and significant complication in elderly patients undergoing surgery. If the mechanisms that underlie it impact brain function intraoperatively, an effective intraoperative marker of brain dysfunction would be useful. However, to date, there is no consensus marker for this aim. We have developed an EEG-based marker-the Brain Reactivity Index (BRI). To assess the efficacy of intraoperative BRI as a marker of acute brain dysfunction that may relate to perioperative cognitive change, we compared its values between patients who showed different ranges of perioperative change in Montreal Cognitive Assessment (MoCA) scores. METHODS: This study analyzed EEG and clinical data from 100 adult cardiac surgery patients to assess whether there might be an association between changes in the Brain Reactivity Index (BRI) and postoperative cognitive changes. RESULTS: The intraoperative BRI was associated with perioperative MoCA changes in older patients (≥65 years), particularly in those with an intermediate (between 21 and 25) preoperative MoCA score. This association was apparent within the first 30 min of anesthesia. In contrast, no such association in BRI values was observed in the younger patient group (<65 years). The proportion of patients with cognitive dysfunction was comparable between the older and younger groups. CONCLUSION: These findings suggest that brain dysfunction, which is associated with perioperative cognitive decline, in older patients may often occur immediately after the induction of anesthesia, highlighting the potential for intraoperative monitoring and intervention. The comparable proportion of patients presenting with perioperative cognitive decline across age groups, along with the transient nature of this decrease in younger patients, suggests that the dysfunction would be temporary, whereas a separate factor may underlie persistent cognitive decline in older individuals. CLINICAL TRIAL REGISTRATION: NCT04512989.

doi.org/10.3389/fnsys.2026.1688834Open accessPubMed 42273253Biomarkers