Can Multiple Surgeries with General Anesthesia Cause Memory Impairment?
Yes, repeated exposure to general anesthesia during multiple surgeries is associated with long-term cognitive decline, including memory impairment, though the effect is subtle and influenced by multiple factors including age, baseline health status, and type of anesthesia used.
Evidence for Cognitive Decline
The most recent high-quality prospective evidence demonstrates that prolonged cumulative exposure to general anesthesia independently contributes to long-term cognitive decline 1. This 2025 MAAS cohort study, following 1,823 adults over 12 years, found that increased total time under general anesthesia negatively affected three cognitive domains: executive functioning, selective attention/mental speed, and information processing speed—even after adjusting for demographic and health factors.
Supporting this, a 2018 Mayo Clinic Study of Aging with 1,819 subjects followed for a median of 5.1 years found that:
- Prior exposure to anesthesia/surgery in the preceding 20 years was associated with greater cognitive decline compared to unexposed individuals 2
- Post-enrollment exposure in previously unexposed individuals showed accelerated decline after exposure
- Over 5 years post-exposure, the additional cognitive decline was 0.2 standard deviations beyond normal aging
Dose-Response Relationship
A 2014 nationwide population-based case-control study of over 26,000 individuals found a dose-response relationship between repeated anesthesia exposure and dementia risk 3:
- Endotracheal intubation general anesthesia (ETGA): OR 1.34 (95% CI 1.25-1.44)
- Intravenous/intramuscular general anesthesia: OR 1.28 (95% CI 1.14-1.43)
- Heavy sedation alone: No increased risk (OR 1.04)
The risk increased with repeated exposures in a dose-dependent manner.
Contradictory Evidence
One 2018 retrospective Chinese case-control study of 577 dementia patients found no association between general anesthesia exposure and cognitive dysfunction 4. However, this study has significant limitations compared to the prospective longitudinal studies, including retrospective design and potential selection bias.
Key Risk Modifiers
Age is the primary risk factor 5, 6, 1. The 2023 JAMA Network Open meta-analysis of 8,382 patients identified:
- Age 65-85 years: OR 2.67 for postoperative delirium
- Age >85 years: OR 6.24 for postoperative delirium
Other significant risk factors that amplify cognitive decline 6, 1, 3:
- Pre-existing cognitive impairment
- Lower education level
- Comorbidities (diabetes, hypertension, atherosclerosis, stroke)
- History of prior delirium
- Polypharmacy (≥5 medications)
- Smoking
- Elevated inflammatory markers (CRP)
Clinical Framework
The 2018 ASA nomenclature guidelines emphasize that perioperative cognitive changes should be classified using the same diagnostic criteria as neurocognitive disorders in the general population (DSM-5 criteria) 5. This means:
- Cognitive complaints after surgery should not be dismissed as separate from other neurocognitive disorders
- 14-48% of individuals >70 years already have mild cognitive impairment before surgery
- Subjective complaints and capacity for activities of daily living should be actively assessed
Critical Caveats
The cognitive decline is subtle but potentially meaningful: For individuals with already low baseline cognition, even small declines can impact functional capacity 2
Memory domains specifically affected: Learning and memory, executive function, selective attention, and processing speed are most vulnerable 1
Anesthesia type matters: Heavy sedation alone does not appear to carry the same risk as general anesthesia with intubation 3
Inflammation plays a role: Peripheral and cerebral inflammation occur with repeated anesthesia/surgery, though middle-aged subjects may be more resilient than elderly patients 7
Amnesia vs. true cognitive impairment: Some apparent memory issues may relate to anesthetic amnesia rather than permanent cognitive decline, particularly with propofol 8
Practical Implications
For patients with multiple planned surgeries:
- Baseline cognitive assessment should be considered, especially in older adults
- Optimize modifiable risk factors (control diabetes, hypertension; reduce polypharmacy)
- Consider regional/neuraxial anesthesia when feasible to minimize general anesthesia exposure
- Monitor for postoperative delirium, which predicts long-term cognitive decline (OR 3.90) 6
- Longer surgical duration increases risk (OR 1.11 per hour) 6
The effect is real but modest: While statistically significant, the clinical significance for an individual patient depends heavily on their baseline cognitive reserve, age, and comorbidity burden.