Abstract: Objective To explore the mechanism of dexmedetomidine (Dex) in preventing postoperative anxiety in elderly patients with carotid stenosis. 
Methods A total of 90 elderly patients with carotid stenosis who underwent carotid artery stenting were recruited as the research subjects. All patients were confirmed as having carotid stenosis by cerebral angiography. The patients were randomly divided into Dex group and control group, with 45 patients in each group. The self-rating anxiety scale (SAS) was used to assess the anxiety level of patients before infusion (T0), at 1 h after operation (T1), 6 h after operation (T2) and 12 h after operation (T3). The mental state of patients was assessed by the mini-mental state examination (MMSE). The patients' pain was evaluated by visual analog scale (VAS), and the expression of autophagy-related protein and apoptosis protein was analyzed by Western blot. 
Results The SAS score of the control group increased initially and then decreased, and the SAS score of Dex group showed a decreasing trend; the SAS score of Dex group was lower than that of control group, and there were statistically significant differences  in interaction between groups, time points, and time points between groups (P＜0.05). The MMSE scores of patients in both groups showed a trend of decreasing initially and then increasing, and the MMSE score of Dex group was higher than that of the control group; There were statistically significant differencess in interaction between groups, time points, and time points between groups (P＜0.05). The VAS scores of patients in both groups showed a trend of initial increasing and then decreasing, the VAS score of Dex group was lower than that of the control group, and there were statistically significant differences in interaction between groups, time points, and time points between groups (P＜0.05). The expression of LC3B-Ⅱ/LC3B-Ⅰand Beclin protein in Dex group was lower than that in control group, while the expression of p62 protein was higher than that of control group (P＜0.05). The Bcl-2 protein expression in Dex group was higher than that in control group, while the expression of Bax and caspase-3 protein was lower than that in control group (P＜0.05). 
Conclusion Dex can reduce postoperative anxiety of elderly patients by inhibiting excessive autophagy of cells and achieve enough sedation effect without causing anxiety. 

Key words: carotid stenosis, dexmedetomidine, anxiety