Table 5.
Association between exposure to surgery with general anaesthesia and PiB PET and FDG PET in cortical regions of interest, and cortical thickness of AD signature regions from structural MRI. Individuals were categorised based on exposure to surgery with general anaesthesia after the age of 40 yr or in the 20 yr before date of imaging. Results are from generalised linear regression for the continuous end points and logistic regression for the abnormal status outcome. All values are comparison to participants who were not exposed to anaesthesia in respective time periods (i.e. after age 40 yr and 20 yr before imaging). In all analyses, anaesthesia was modelled as any anaesthetic in the given time frame compared with none. ∗Because of skewed residuals, the natural log of the PIB region of the posterior cingulate and precuneus was modelled. Estimates are for the multiplicative increase in end point associated with exposure to anaesthesia in the given time frame compared with no exposure. †Estimates are for the increase in end point associated with exposure to anaesthesia in the given time frame. ‡Estimates are odds ratios associated with exposure to anaesthesia in the given time frame compared with no exposure. AD signature region includes the surface-area weighted average of the mean global thickness in the entorhinal, inferior temporal, middle temporal, and fusiform regions. CI, confidence interval; FDG, 18-fluorodeoxyglucose; PiB PET, Pittsburgh compound B positron emission tomography.
| Imaging metrics | Exposure to surgery with general anaesthesia |
|||
|---|---|---|---|---|
| Since age 40 yr |
In the prior 20 yr |
|||
| Estimate (95% CI) | P-values | Estimate (95% CI) | P-values | |
| PIB PET region of the posterior cingulate and precuneus∗ | 1.00 (0.95, 1.07) | 0.885 | 0.98 (0.93, 1.03) | 0.402 |
| FDG PET region of the posterior cingulate and precuneus† | 0.004 (–0.029, 0.036) | 0.812 | –0.003 (–0.029, 0.024) | 0.836 |
| FDG PET ratio of the inferior temporal/medial temporal† | 0.006 (–0.011, 0.023) | 0.463 | 0.008 (–0.006, 0.022) | 0.259 |
| FDG PET region of the anterior cingulate† | 0.016 (–0.004, 0.036) | 0.129 | 0.010 (–0.007, 0.026) | 0.250 |
| AD signature region | ||||
| Abnormal cortical thickness‡ | 1.98 (1.18, 3.31) | 0.010 | 1.64 (1.05, 2.55) | 0.029 |
| Cortical thickness (mm)† | –0.037 (–0.078, 0.003) | 0.070 | –0.029 (–0.062, 0.004) | 0.088 |