Summary: Researchers report no increased risk of being diagnosed with dementia for older adults who received general anesthesia compared with those who received regional anesthesia during elective surgery.
Source: Wiley
Background: There has been ongoing concern that exposure to general anesthesia during surgery might raise the long-term risk of Alzheimer’s disease or other dementias. To address this question, investigators compared outcomes for older adults who received general anesthesia (GA) with those who received regional anesthesia (RA) during elective procedures, using population-level health data and rigorous matching methods.
This analysis, published in the Journal of the American Geriatrics Society, followed community-dwelling adults aged 66 and older who underwent one of five elective surgeries in Ontario, Canada, between April 1, 2007, and March 31, 2011. After excluding individuals with existing dementia, researchers used propensity-score matching within each surgical procedure to create comparable groups for GA and RA, resulting in 7,499 matched pairs. Participants were tracked for up to five years after their surgery to identify new diagnoses of dementia.
The main finding was that exposure to general anesthesia for elective surgery was not associated with a higher long-term risk of being diagnosed with dementia compared with regional anesthesia. The hazard ratio (HR) for dementia among those who received GA versus RA was 1.0 (95% confidence interval [CI] = 0.8–1.2), indicating no detectable increase in risk. Subgroup and sensitivity analyses produced consistent results in most comparisons.
“Many older adults experience changes in their cognition immediately following surgery and wonder what role the type of anesthetic might have played in these changes,” said senior author Dallas P. Seitz, MD, PhD, FRCPC, of the University of Calgary. “Our study provides evidence that the anesthetic technique used during elective surgeries—general anesthesia or regional anesthesia—is not associated with a long-term increased risk of developing dementia.”
Implications: For clinicians and older adults planning elective surgery, these findings suggest that the choice between general and regional anesthesia should not be driven by concerns about long-term dementia risk alone. Immediate postoperative cognitive changes, sometimes experienced by older patients, remain a clinical concern, but this study indicates those early changes do not necessarily translate into a higher rate of dementia within five years when comparing anesthetic techniques.
Study strengths and limitations: The study’s strengths include a large, population-based sample, careful matching on demographic and clinical factors, and use of a validated administrative algorithm to identify dementia diagnoses. The follow-up period of up to five years allowed for assessment of medium-term outcomes. Limitations include reliance on administrative data rather than clinical adjudication for every dementia case, the focus on elective procedures only (so results may not generalize to emergency surgery), and the possibility that very long-term effects beyond five years were not captured.
Conclusion: In this matched cohort of older adults undergoing elective surgery, general anesthesia was not associated with an increased overall risk of a subsequent dementia diagnosis compared with regional anesthesia over a follow-up period of up to five years. The authors note that further research is needed to determine whether undergoing surgery itself—regardless of anesthetic technique—might influence dementia risk over longer time frames or in different patient groups.
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Source: AAAS
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Image: The image is credited to B. Conlon et al., Science Translational Medicine (2020).
Abstract
Association Between Exposure to General Versus Regional Anesthesia and Risk of Dementia in Older Adults
BACKGROUND/OBJECTIVES
Cognitive changes are commonly observed in older adults following surgery, and there is concern that exposure to general anesthesia could contribute to later development of Alzheimer’s disease or other dementias. This study examined whether exposure to general anesthesia compared with regional anesthesia for elective procedures is associated with an increased rate of dementia diagnoses in older adults.
DESIGN
Population-based, propensity score–matched retrospective cohort study.
SETTING
Linked administrative health databases from ICES in Ontario, Canada, provided the data for this analysis.
PARTICIPANTS
The cohort included community-dwelling individuals aged 66 and older who underwent one of five elective surgical procedures in Ontario between April 1, 2007, and March 31, 2011. Individuals with evidence of dementia before cohort entry were excluded. Those who received general anesthesia were matched within surgical procedures to individuals who received regional anesthesia on age, sex, year of cohort entry, and a propensity score accounting for potential confounding factors.
MEASUREMENTS
Baseline characteristics were compared before and after matching. Participants were followed for up to five years for occurrence of dementia identified through a validated administrative algorithm. Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between anesthetic type and subsequent dementia. Preplanned subgroup and sensitivity analyses assessed robustness of results.
RESULTS
The final analysis included 7,499 matched pairs. There was no overall difference in risk of being diagnosed with dementia for individuals who received general anesthesia compared with those who received regional anesthesia (HR = 1.0; 95% CI = 0.8–1.2). Most subgroup and sensitivity analyses supported the same conclusion.
CONCLUSION
Elective surgery performed under general anesthesia was not associated with an increased risk of dementia compared with regional anesthesia over a follow-up period of up to five years in this older adult population. Further research is warranted to explore whether surgery itself influences dementia risk over longer durations or in different populations.