Abnormal metabolic network activity in REM sleep behavior disorder.
OBJECTIVE
To determine whether the Parkinson disease-related covariance pattern (PDRP) expression is abnormally increased in idiopathic REM sleep behavior disorder (RBD) and whether increased baseline activity is associated with greater individual risk of subsequent phenoconversion.


METHODS
For this cohort study, we recruited 2 groups of RBD and control subjects. Cohort 1 comprised 10 subjects with RBD (63.5 ± 9.4 years old) and 10 healthy volunteers (62.7 ± 8.6 years old) who underwent resting-state metabolic brain imaging with (18)F-fluorodeoxyglucose PET. Cohort 2 comprised 17 subjects with RBD (68.9 ± 4.8 years old) and 17 healthy volunteers (66.6 ± 6.0 years old) who underwent resting brain perfusion imaging with ethylcysteinate dimer SPECT. The latter group was followed clinically for 4.6 ± 2.5 years by investigators blinded to the imaging results. PDRP expression was measured in both RBD groups and compared with corresponding control values.


RESULTS
PDRP expression was elevated in both groups of subjects with RBD (cohort 1: p < 0.04; cohort 2: p < 0.005). Of the 17 subjects with long-term follow-up, 8 were diagnosed with Parkinson disease or dementia with Lewy bodies; the others did not phenoconvert. For individual subjects with RBD, final phenoconversion status was predicted using a logistical regression model based on PDRP expression and subject age at the time of imaging (r(2) = 0.64, p < 0.0001).


CONCLUSIONS
Latent network abnormalities in subjects with idiopathic RBD are associated with a greater likelihood of subsequent phenoconversion to a progressive neurodegenerative syndrome.
From the Center for Neurosciences (F.H., Y.M., C.C.T., A.F., V.D., D.E.), The Feinstein Institute for Medical Research, Manhasset, NY; Center for Advanced Research in Sleep Medicine (J.-F.G., R.B.P., M.V., J.M.), Hôpital du Sacré-Coeur de Montréal; Department of Psychology (J.-F.G., M.V.), Université du Québec à Montréal; Department of Neurology (R.B.P.), Montreal General Hospital; Montreal Neurological Institute (J.-P.S.), McGill University; and Department of Psychiatry (J.M.), University of Montreal, Montréal, Canada.
Florian
F
Holtbernd
Jean-François
JF
Gagnon
Ron B
RB
Postuma
Yilong
Y
Ma
Chris C
CC
Tang
Andrew
A
Feigin
Vijay
V
Dhawan
Mélanie
M
Vendette
Jean-Paul
JP
Soucy
David
D
Eidelberg
Jacques
J
Montplaisir
D000368:Aged; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D020961:Lewy Body Disease / Q000150:complications / Q000378:metabolism; D008875:Middle Aged; D064847:Multimodal Imaging; D010300:Parkinson Disease / Q000150:complications / Q000378:metabolism; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D020187:REM Sleep Behavior Disorder / Q000150:complications / Q000175:diagnosis / Q000378:metabolism*; D016037:Single-Blind Method; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18