Parkinson's disease-related non-motor features as risk factors for post-operative delirium in spinal surgery

BACKGROUND: The clinical features of postoperative delirium are similar to the core features of alpha synuclein-related cognitive disorders, such as Parkinson’s disease dementia (PDD) or dementia with Lewy bodies (DLB). Therefore, we hypothesized that the non-motor symptoms (NMSs) in Parkinson’s disease (PD), which precede the cardinal motor features of PD, are likely to be risk factors for developing postoperative delirium. We investigated the association between PD-related NMSs and postoperative delirium in old people undergoing elective spinal surgery. METHODS: This study was a prospective study. Participants were aged 65 years and older and scheduled to undergo elective spinal surgery. During the enrollment period, 338 individuals were screened, 104 participants were included in the analysis. We assessed eight easily-assessed and representative PD-related NMSs 1 day before the scheduled surgery using tests or questionnaires for each symptom. The presence of delirium was determined by using the short version of the Confusion Assessment Method (CAM). RESULTS: Fifteen (14.4%) of the 104 participants (age, 71.7 ± 4.7 years; men, 34.6%) met the CAM criteria for post-operative delirium. Multivariate logistic analysis showed that decreased olfactory function (odds ratio [OR] 0.63, 95% CI 0.44–0.91) and exhibiting rapid eye movement sleep behavior disorder (RBD, OR 1.45, 95% CI 1.09–1.93) were significantly independent predictors of postoperative delirium. CONCLUSIONS: Our study shows that hyposmia and RBD are significantly independent risk factors for postoperative delirium in general elderly population. Considering that NMSs may represent burden of alpha synuclein deposit, we postulate that an underlying alpha synucleinopathy may correlates with postoperative delirium. SIGNIFICANCE: This study gives a novel insight for the risk factor of postoperative delirium.