JNNP: Olfactory impairment as an early sign of Parkinson's disease in rapid eye movement sleep behavior disorders: systematic review and meta-analysis

Rapid Eye Movement (REM) Sleep Behavior Disorder (RBD) is a sleepiness and movement disorder.
RBD is characterized by loss of normal muscle dystropne during REM sleep, accompanied by dreaming.
clinical significance of RBD includes never-before-noticed sleep interruptions to severe self-harm behavior and/or injury to bed companions.
RBD has traditionally been classified as iditable or secondary to neurodegenerative diseases, usually representing the precursor period of α-synth nuclear protein disease.
with RBD are often male and usually between 40 and 70 years of age.
, a video multi-guided sleep map (PSG) study estimated the prevalence of RBD in the general population at 1.06 percent.
RBD is considered to be the initial symptom of neurodegenerative disorders, a recent meta-analysis of 51 longitudinal studies found that the proportion of patients with RBD developing neurodegenerative diseases after 5 years was 34%, 82% after 10.5 years and 97% after 14 years.
, early detection and diagnosis of RBD is important for improving the progress of neurodegenerative diseases.
between olfactory damage and neurodegenerative diseases has been increasingly recognized.
prevalence of olfactory impairment in people with Parkinson's disease (PD), as well as the low difficulty and low cost of evaluation, make olfactory an attractive biomarker of PD.
, olfactory function is also associated with other non-motor characteristics of Parkinson's disease and may be a predictive indicator of cognitive decline in neurodegenerative diseases.
some studies have focused on the sense of smell in RBD patients, but a systematic understanding of the link remains lacking.
these studies, different olfactory assessment tools, inconsistent RBD diagnostic criteria, and smaller study populations led to uncertain results.
This paper provides a systematic review and comprehensive meta-analysis of existing studies to explore the significance of olfactory function in the diagnosis and prognosis (risk of transition to PD) in RBD patients, and to evaluate the regulatory factors that affect olfactory function.
researchers (ZL and SZ) independently conducted systematic searches of relevant literature in the PubMed, Science Network, Embase, PsycINFO, and Scopus databases.
designed a specific extract table for this meta-analysis, including: (1) demographic data included in the individual;
subject to the olfactory results average and the depression self-assessment scale (SDs) as the cause variables, demographic data, disease course, olfactory assessment tools, diagnostic criteria and test scale scores as adjustment variables.
meta-analysis to obtain a quantitative assessment of olfactory function in RBD and PD patients.
addition, we performed meta-regression analysis of data from RBD patients.
statistical analysis is performed using Stata V.12.0 software.
reviewing the title and summary of 3,104 articles, this article examines the full text of 394 articles in detail.
, 32 studies that met the standards were selected for systematic review, of which 28 were meta-analysis.
all selected studies have an HC group.
this paper found that 14 studies had both RBD and PD patients, and 18 studies had only RBD patients.
, however, one of the studies of patients with both RBD and PD provided only olfactory function data for RBD patients.
The olfactory results in this study were divided into four categories: odor recognition (assessed in 24 studies), thresholds (assessed in 9 studies), discrimination (assessed in 7 studies), and overall olfactory function (assessed by the total score of the other three functions in 9 studies).
32 studies involving 3,342 participants (1,366 RBD patients, 555 RBD-free PD patients, 138 PD and RBD patients, and 1,283 HCs patients) were included in the systematic evaluation of this paper.
sample size was 11-202 in patients with RBD, 11-151 in patients without RBD, 8-42 in patients with PD and RBD, and 12-336 in patients with HC.
age of RBD patients was 48.20 to 71.80 years, the average age of PD patients without RBD was 60.60 to 70.00 years, the average age of PD and RBD patients was 68.80 to 70.70 years, and the average age of HCs patients was 48.20 to 71.00 years.
conducted different olfactory assessments in these studies to test olfactory function.
In the analysis of systematic review and meta-analysis, this paper includes only studies that have clear diagnostic criteria for patients with RBD and/or PD: 19 studies use diagnostic criteria for the International Classification of Sleep Disorders (ICSD) (including ICSD, ICSD-2, and ICSD-3), and 11 studies use PSG for RBD validation.
one study used the diagnostic criteria of Sleep Medicine Principles and Practice 4 (PPSM-4), and another used PSG or PPSM or ICSD to demonstrate RBD.
all Parkinson's patients involved in the study met the British Parkinson's Society's brain bank standards, but one study used the Parkinson's disease diagnostic criteria recommended by the European Federation of Neurological Societies.
, the lack of useful statistics for quantitative analysis excluded four studies from the systematic review, leaving only 28.
of these studies, 24 studies evaluated odor recognition (14 for RBD patients only, 10 for RBD patients and PD patients), 9 studies assessed odor thresholds (6 studies for RBD patients only, 3 studies for RBD patients and P D patients), 7 studies evaluated odor identification (5 studies were for RBD patients, 2 studies were for RBD patients and PD patients), 9 studies evaluated overall olfactory function (7 studies were for RBD patients only, 2 studies were for RBD patients and PD patients).
we conducted a separate meta-analysis study to assess the three areas of smell and the overall olfactory function as described below.
Fewer than five studies assessed odor thresholds, discernment, or overall olfactory function in PD patients;
used data from nine studies to compare odor thresholds between 312 RBD patients and 271 control groups.
, the odor threshold capacity of RBD patients was significantly lower than that of HCs.
used data from seven studies to compare odor recognition in 265 RBD patients and 213 HCs patients, showing that the odor recognition in RBD patients was significantly lower than in control group HCs.
four studies compared the olfactory function scores of RBD patients with 9D and RBD patients.
only two studies compared odor recognition scores for 29 patients (RBD and PD) and 61 patients (RBD).
of patients with RBD were similar to those of RBD and PD patients, and the heterogeneity in the study was lower.
analyzed data from seven studies and compared the odor recognition scores of 218 RBD patients and 473 PD patients, with a similar odor recognition score for RBD patients to PD patients.
, RBD patients suffer from severe olfactory impairments, including deficiencies in olfactory recognition, thresholds, discernment, and overall olfactory function.
these defects are not related to age, gender, course of illness, or years of education, but to the UPDRS III score.
specifically, similar odor recognition disorders (with or with potential RBD) were found in RBD patients and PD patients.
findings suggest that olfactory impairment may be a sensitive and stable diagnostic biomarker of RBD, and it appears to help identify high-risk iRBD patients who convert to PD early.
Lyu Z, Zheng S, Zhang X, et al Olfactory as an early marker of Parkinson's disease in REM sleep disorder behaviour: a system review and meta-analysis Journal of Neurology, Neurosurgery and Psimology Published Online First: 12 January 2021. doi: 10.1136/jnnp-2020-325361MedSci Original Source: MedSci Original Copyright Notice: All notes on this website "Source: Met Medical" or "Source: MedSci Original" text, pictures and audio and video materials, copyrights belong to Mays No media, website or individual may be reproduced without authorization, which must be reproduced with the following "Source: Metz Medicine".
all reprinted articles on this website are for the purpose of transmitting more information and clearly indicate the source and author, and media or individuals who do not wish to be reproduced may contact us and we will delete them immediately.
at the same time reproduced content does not represent the position of this site.
leave a message here