Figure 2.

Forest plot for overall studies showing the risk of Alzheimer's disease (AD) following general anesthesia. An effect size of 1 (red vertical line) indicates no effect of general anesthesia in development of AD. The gray-colored box of each study means the weight of the study data. Overall pooled effect size showed significantly increased risk of AD following general anesthesia. Above 6 studies are subgroup of cohort studies, and following 17 studies are subgroup of case-control studies. Both of them showed significantly high risk of AD following general anesthesia.