We evaluated the role of cognitive and brain reserve markers in modifying the risk of postoperative delirium associated with a pathophysiologic marker. The Successful Aging after Elective Surgery study (SAGES) enrolled 556 adults age ≥70 years without dementia scheduled for major surgery. Patients were assessed preoperatively and daily during hospitalization for delirium. We used C-reactive protein (CRP) as a pathophysiologic marker of inflammation, previously associated with delirium. Markers of reserve included vocabulary knowledge, education, cognitive activities, occupation type and complexity, head circumference, intracranial volume, and leisure activities. Vocabulary knowledge, cognitive activities, and education significantly modified the association of CRP and postoperative delirium (P < .01). However, effect sizes—when statistically significant—were small in magnitude. The strongest effect modification was observed for vocabulary knowledge: high scores were generally protective but not at high levels of CRP. Select reserve markers attenuate the risk of delirium associated with lower grade inflammatory processes, supporting the role of reserve in delirium.
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