Association of global DNA hypomethylation with post-operative cognitive dysfunction in elderly patients undergoing hip surgery.

Background: Post-operative cognitive dysfunction (POCD) is a decline of cognitive status that commonly occurs after surgery in elderly patients. Whether DNA methylation is associated with the development of POCD remains unclear.

Methods: Subjects (N = 124) older than 65 years-of-age undergoing hip replacement surgery were enrolled. A battery of neuropsychiatric tests was used to examine the perioperative cognitive function of the patients. Early POCD was analyzed using the reliable change index (RCI), and subjects were diagnosed with POCD if RCI < -1.96. Peripheral leukocyte DNA was isolated, and DNA methylation was measured via 5-methylcytosine (mC) using Elisa.

Results: Twenty-four patients (19.4%) developed early POCD. There was no difference in baseline 5-mC levels by POCD status. The 5-mC levels significantly decreased on day 7 after surgery in patients who developed early POCD (P = .004), but did not change in non-POCD patients. Moreover, post-operative 5-mC levels were significantly lower in POCD patients than those in non-POCD patients (P = .003). Bivariate logistic models adjusted for age, gender, BMI, duration of anesthesia, and education level clearly demonstrated an independent association between post-operative 5-mC level and early POCD.

Conclusions: Post-operative global hypomethylation of leukocyte DNA was associated with the development of early POCD.

Trial Registration: ClinicalTrial, NCT02965235. Registered 16 November 2016, https://www.clinicaltrials.gov/ct2/results?term=NCT02965235&rank=1#rowId0.