Does General Anesthesia Influence Long-Term Cognition or Dementia Risk? A systematic review of postoperative cognitive trajectory in older adults

Background: General anesthesia (GA) is commonly administered to older adults undergoing surgery, raising concern that anesthetic exposure may contribute to cognitive decline or dementia. Although short-term postoperative cognitive dysfunction is known, its relationship to later-life cognitive outcomes remains uncertain. We systematically reviewed studies examining whether GA exposure in older adults is associated with cognitive impairment.

Methods: Following PRISMA 2020 guidelines, we searched PubMed, Embase, and the Cochrane (2000-2025). Of 97 records identified, 13 duplicates were removed, 84 unique records were screened, 21 full-text articles were assessed, and 5 observational cohort studies met inclusion criteria (adults ≥60 years with GA exposure and cognitive follow-up ≥3 months). Studies limited to regional anesthesia, sedation without GA, or lacking objective cognitive outcomes were excluded. Risk of bias was assessed using the Newcastle-Ottawa Scale.

Results: Among the included studies, evidence on GA’s cognitive impact was mixed. Two large cohort studies (n≈1,700-1,800 each) using neuropsychological test scores reported that cumulative GA exposure was associated with a small but significant acceleration of cognitive decline (≈0.2 SD additional 5-year decline). Conversely, another cohort (n≈4,000) found no increased risk of dementia or Alzheimer’s disease associated with GA (0.86, 95% CI 0.58-1.28). In two smaller surgical cohorts, 25% exhibited transient slowing in processing speed at 3 weeks after GA, and 34% showed objective cognitive decline at 3 months postoperatively. Only 13% perceived cognitive problems and subjective complaints were more linked to depressive symptoms.

Conclusion: Limited evidence suggests that GA in older adults is not strongly linked to permanent cognitive deterioration or dementia. GA may modestly hasten cognitive decline in some individuals, but significant long-term impairment has not been consistently demonstrated. Short-term cognitive changes occur in a subset of patients but resolve within months. Overall, the cognitive impact of GA appears mild, with other factors likely playing larger roles in late-life cognitive health.