New Test Predicts Cognitive Dysfunction Risk in Elderly Surgery Patients

About half of older adults who appear cognitively normal experience issues with thinking, memory, or focus following surgery. The primary factor indicating post-surgery cognitive impairment is pre-existing cognitive issues. Conventional cognitive tests assess language, short-term memory, and awareness of time and place, but these may not always reveal underlying cognitive vulnerabilities, leaving some individuals unaware of their susceptibility to cognitive complications after surgery. Now, a new method offers a simple way to identify older patients at risk for post-operative cognitive dysfunction.

Researchers at Duke Health (Durham, NC, USA) discovered that a basic EEG can identify signs of cognitive vulnerability when patients are instructed to close and then open their eyes. This pre-surgical, non-invasive brainwave analysis can predict which patients might suffer from confusion and concentration issues post-surgery. The Duke team utilized EEG to detect changes in brain electrical patterns, particularly during eye movements. When individuals close and then open their eyes, there's a shift in specific electrical activity patterns in the brain known as alpha oscillations. This shift, termed alpha attenuation, involves a reduction in alpha oscillations when transitioning from closed to open eyes. Typically, EEG-measured alpha power is lower during visual processing with open eyes and higher when internally focused or daydreaming. In healthy older adults, this decrease in alpha power from eyes-closed to eyes-open states is pronounced but is less so in those with chronic neurocognitive disorders.

Leveraging this insight, the Duke team developed a predictive test using a quick, pre-surgery EEG. They evaluated 71 patients, all aged over 60 and not undergoing neurological or cardiac surgery, with a simple task of closing and opening their eyes to detect arousal or attention disorders. The test effectively identified patients likely to face postoperative inattention and the extent of their potential cognitive issues. Although the reasons behind worsening cognitive impairments in older patients after surgery and anesthesia remain unclear, pinpointing those at risk could aid in evaluating the implications of surgical procedures and preparing for possible complications.

“This test is quite simple to perform and could prepare clinicians to take precautionary measures to reduce the risk for postoperative inattention, and possibly delirium,” said Leah Acker, M.D., Ph.D., assistant professor in Duke’s Department of Anesthesiology. “More generally, because the brain’s reaction to something as simple as opening one’s eyes is closely associated with specific attention functions, we expect that this may yield insights into the neural mechanisms underlying neurocognitive vulnerability and resilience.”

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