Association Between Cognitive Decline And Hyposmia In Parkinson's Disease

Objective: The aim of our study was to study the association between hyposmia and cognitive decline in Parkinson's disease(PD)patients and also to investigate specific impaired cognitive domains in PD with hyposmia.Methods: A total of 577 patients with idiopathic PD were enrolled from Parkinson's disease and movement disorder clinic during January 2014 to December 2018.Hyposmia was defined as Sniffin' Sticks test-16(SS-16)less than 8.3 and the participants were divided into PD with and without hyposmia groups.The demographic characteristics were recorded.MMSE and MOCA score and scale results of other non-motor symptoms were compared between the two groups.The relationship between olfactory function and MOCA item score was also analyzed.Results: There were 358 patients in PD with hyposmia group accounting for 62.0% of PD patients.Both of age(P<0.001)and male proportion(P=0.009)were significantly increased in PD with hyposmia.There was no significant difference between the two groups in cpRBD,EDS and nighttime sleep quality.The symptoms of depression and anxiety were also similar in the two groups.No significant difference in MMSE score were found but MOCA score was significantly lower in PD with hyposmia(P=0.004).After adjusting the gender,age and disease duration,cognitive decline was a risk factor for hyposmia in PD(OR=0.945,P=0.025).In the hyposmic group,score of 3 MOCA items including abstraction(P=0.009),language(P=0.040)and delayed recall(P=0.030)was significantly lower than those in the normosmic group among which abstraction was found to be significantly associated with olfactory function in PD after the adjustment of sex,age and disease duration(OR=0.676,P=0.007).Conclusion: There was a significant association between cognitive and olfactory function in PD patients.Worse MOCA performance was a risk factor for hyposmia in PD and abstraction ability decline was significantly associated with olfactory dysfunction.Objective: Our study aimed at comparing ERPs components and their relationships with specific cognitive domains between Parkinson's disease(PD)with and without hyposmia.Methods: A total of 43 patients with idiopathic PD were enrolled from Parkinson's disease and movement disorder clinic during September 2016 to October 2017.The patients were divided into the hyposmic and normosmic groups with Sniffin' Sticks test-16(SS-16)cutoff score of 8.3.The ERPs data was recorded during the delayed match-to-sample task(DMST).ERPs components including N1,N2,P1,P2 and P3 during the retrieval period of DMST were analyzed and then compared between the two groups.The association between ERPs components and MOCA item performance was also analyzed within two groups.Results: There was no significant difference in five ERPs components between PD with and without hyposmia.Among all participants,N1 latency was negatively correlated with visuospatial/executive item score(rs=-0.381,P=0.012),and P1 amplitude was positively correlated with language item score(rs=0.302,P=0.049).Within the normosmic group,N1 latency was significantly associated with visuospatial/executive item score(rs=-0.619,P=0.005)and P1 amplitude was significantly related to language ability(rs=0.537,P=0.018).In the hyposmic group,no correlation was found between P1 and language and there was the only association between N1 latency and clock drawing test score but not visuospatial/executive item performance(rs=-0.413,P=0.045).Conclusion: No significant difference in ERPs components was found between the hyposmic and normosmic groups.In PD without hyposmia,N1 latency was negatively correlated with visuospatial/executive function and P1 amplitude was positively correlated with language ability.However,in PD with hyposmia,no relation was found between P1 and language and there was the only association between N1 latency and clock drawing test score but not visuospatial/executive item performance.