Anesthesia Exposure and Risk of Dementia and Alzheimer’s Disease: A Prospective Study

Background/Aims: Studies have demonstrated conflicting results about the association between anesthesia exposure and subsequent dementia risk. However, prior studies were retrospective, collecting data on anesthesia exposure after determining dementia status. We used prospectively collected data to evaluate the associations between anesthesia and risk of dementia or Alzheimer’s disease (AD). Methods: We conducted a cohort study among community-dwelling members of the Adult Changes in Thought cohort (N = 3,988) who were age 65 or older and free of dementia at baseline. Participants self-reported all prior surgical procedures with general or neuraxial (spinal or epidural) anesthesia at baseline and reported new procedures every two years. We compared people who had high-risk surgery with general anesthesia, other surgery with general anesthesia, and other surgery with neuraxial anesthesia exposures to those who had no surgery and no anesthesia. We used Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for dementia and AD associated with time-varying lifetime and recent (past 5 years) anesthesia exposures. Results: At baseline, 254 (6%) people reported never having anesthesia; 248 (6%) had one or more high-risk surgeries with general anesthesia, 3,363 (84%) had one or more other surgeries with general anesthesia, and 123 (3%) had one or more surgeries with neuraxial anesthesia. Lifetime exposure of high-risk surgery with general anesthesia was not associated with an increased risk of dementia (HR: 0.86, 95% CI: 0.58–1.28) or AD (HR: 0.95, 95% CI: 0.61–1.49) relative to no history of anesthesia. People with lifetime exposure of other surgery with general anesthesia had a lower risk of dementia (HR: 0.63, 95% CI: 0.46–0.85) and AD (HR: 0.65, 95% CI: 0.46–0.93) than people with no history of anesthesia. There was no association between recent anesthesia exposure and dementia or AD. When comparing the results for high-risk surgery with general anesthesia directly to other surgery with general anesthesia, HR was 1.37 (95% CI: 1.04–1.80) for dementia and 1.46 (95% CI: 1.07–1.99) for AD. Conclusion: Anesthesia exposure was not associated with an increased risk of dementia or AD in older adults. Future studies should continue to explore whether there is truly an increased risk of dementia and AD following high-risk surgery