Olfactory dysfunction predicts early transition to a Lewy body disease in idiopathic RBD

Publication

Olfactory dysfunction predicts early transition to a Lewy body disease in idiopathic RBD

Journal Paper/Review - Jan 21, 2015

Mahlknecht Philipp, Seppi Klaus, Poewe Werner, Scherfler Christoph, Brugger Florian, Goebel Georg, Gschliesser Viola, Mitterling Thomas, Serradell Monica, Tolosa Eduardo, Santamaria Joan, Müller Christoph, Frauscher Birgit, Högl Birgit, Iranzo Alex, Sleep Innsbruck Barcelona Group

Citation

Mahlknecht P, Seppi K, Poewe W, Scherfler C, Brugger F, Goebel G, Gschliesser V, Mitterling T, Serradell M, Tolosa E, Santamaria J, Müller C, Frauscher B, Högl B, Iranzo A, Sleep Innsbruck Barcelona Group. Olfactory dysfunction predicts early transition to a Lewy body disease in idiopathic RBD. Neurology 2015; 84:654-8.

Type

Journal Paper/Review (English)

Journal

Neurology 2015; 84

Publication Date

Jan 21, 2015

Issn Electronic

1526-632X

Pages

654-8

Brief description/objective

OBJECTIVE
The aim of the present study was to determine the predictive value of olfactory dysfunction for the early development of a synuclein-mediated neurodegenerative disease in subjects with idiopathic REM sleep behavior disorder (iRBD) over an observational period of 5 years.

METHODS
Thirty-four patients with polysomnography-confirmed iRBD underwent olfactory testing using the entire Sniffin' Sticks test assessing odor identification, odor discrimination, and olfactory threshold. Patients with iRBD were prospectively followed up over a period of 4.9 ± 0.3 years (mean ± SD). The diagnosis of neurodegenerative diseases was based on current clinical diagnostic criteria.

RESULTS
After 2.4 ± 1.7 years (mean ± SD), 9 patients (26.5%) with iRBD developed a Lewy body disease (6 Parkinson disease and 3 dementia with Lewy bodies). The entire Sniffin' Sticks test and the identification subtest had the same overall diagnostic accuracy of 82.4% (95% confidence interval: 66.1%-92.0%) in predicting conversion. The relative risk for a Lewy body disease in the lowest tertile of olfactory function was 7.3 (95% confidence interval: 1.8-29.6) compared with the top 2 tertiles.

CONCLUSIONS
Assessment of olfactory function, particularly odor identification, may help to predict the development of a Lewy body disease in patients with iRBD over a relatively short time period and thus to identify patients suitable for future disease modification trials.