Exposure to general anesthesia may raise dementia risk

  • Evidence suggested that individuals exposed to general anesthesia may have a modestly elevated risk for dementia.

Why this matters

  • Dementia is a major public health burden.
  • Data from individual studies on dementia have been mixed.
  • Factors such as genetics or comorbidity could influence any relationship.

Key results

  • For all studies pooled, relative to nonexposed peers, individuals exposed to general anesthesia did not have a significantly elevated risk for dementia, a finding seen in the majority of subgroups evaluated.
  • When analysis was restricted to studies that ascertained exposure from medical records, individuals exposed to general anesthesia did have a significantly elevated dementia risk (OR, 1.22).
  • A dose-response analysis of 3 studies showed a nonlinear relationship whereby risk rose more sharply with increasing number of exposures (P<.0001).

Study design

  • A meta-analysis of 19 studies (7 prospective cohort studies, 11 case-control studies, and 1 pooled analysis of 6 case-control studies) among 154,421 individuals.
  • Main outcome was incident dementia.
  • Funding: National Natural Science Foundation of China; Provincial Natural Science Foundation of Liaoning.


  • Findings may have been affected by residual confounding.
  • Method of assessing exposure varied.
  • Heterogeneity across studies was high.
  • All studies were observational in nature.