Smaller subcortical volume in Parkinson patients with rapid eye movement sleep behavior disorder

Abstract

Parkinson disease (PD) patients with rapid eye movement (REM) sleep behavior disorder (RBD) have worse motor symptoms and non-motor symptoms than patients without RBD. The aim of this study was to examine underlying differences in brain structure from a network perspective. Baseline data were obtained from Parkinson's Progression Markers Initiative (PPMI) participants. We divided PD patients and healthy controls (HC) into RBD positive and RBD negative using a cutoff score of ≥5 on the RBD screening questionnaire. HC with probable RBD were excluded. We first carried out a region-of-interest analysis of structural MRIs using voxel-based morphometry to study volumetric differences for the putamen, thalamus and hippocampus in a cross-sectional design. Additionally, an exploratory whole-brain analysis was performed. To study group differences from a network perspective, we then performed a 'seed-based' analysis of structural covariance, using the bilateral dorsal-caudal putamen, mediodorsal thalamus and anterior hippocampus as seed regions. The volume of the right putamen was smaller in PD patients with RBD. RBD symptom severity correlated negatively with volume of the right putamen, left hippocampus and left thalamus. We did not find any differences in structural covariance between PD patients with and without RBD. Presence of RBD and severity of RBD symptoms in PD are associated with smaller volumes of the putamen, thalamus and hippocampus.

Altered Brain Functional Network in Parkinson Disease With Rapid Eye Movement Sleep Behavior Disorder

“…It also regulates sleep and wakefulness. Some previous morphometry studies showed markedly reduced gray matter volume in the bilateral thalamus of PD-pRBD patients in comparison with PD-npRBD patients and the volume of thalamus is negatively correlated with RBDSQ scores (7,8,12). And some previous functional studies also reported changes of thalamus function.…”

“…Based on these results, we speculate that the increased betweenness centrality of the left insula is compensatory to volume decrease and pathological involvement to maintain the overall information conversion efficiency of the brain. However, some studies based on morphometry did not find any significant difference in limbic system (7,12,14). The difference may be due to the size of the sample and the severity of the patient's symptoms.…”

“…Some researchers successively explored structure changes in PD-RBD patients using voxel-based morphometry, diffusion tensor imaging and structural correlation network methods. They found PD-RBD has decreased volume in more or less cortical and subcortical structures such as thalamus, hippocampus, and cingulate cortex (6)(7)(8)(9)(10)(11)(12). In addition to brain structure, a few researchers also used the resting-state functional MRI (rs-fMRI) to search changes of brain function in PD-RBD.…”

Neuroimaging Advances in Parkinson's Disease and Atypical Parkinsonian Syndromes

“…In PD patients with polysomnography-confirmed rapid eye movement sleep behavior disorder (RBD), cortical thinning was reported in the right perisylvian and inferior temporal cortices together with shape changes in the putamen compared to PD without RBD ( 42 ). Likewise, decreased volume in the right putamen correlating with RBD symptom severity was identified in PD with RBD vs. those without ( 43 ). On susceptibility-weighted imaging, loss of dorsal nigral hyperintensity (corresponding to nigrosome-1) was observed in ~25% of patients with idiopathic RBD, which associated with lower putaminal dopamine transporter (DAT) binding on single-photon emission computed tomography (SPECT) ( 44 ).…”

Abnormal Gray Matter Volume and Functional Connectivity in Parkinson’s Disease with Rapid Eye Movement Sleep Behavior Disorder

“…Some studies have found that these patients had reduced gray volume in the thalamus, putamen, lingual gyrus, cerebellum, pontomesencephalic tegmentum, amygdala, anterior cingulate gyrus, posterior cingulate gyrus, and hippocampus [ 12 – 16 ]. However, some methodological limitations are still shown in these studies, especially the lack of diagnosis of RBD by polysomnography (PSG) [ 13 , 15 ]. Studies have indicated changes in functional connectivity (FC) in idiopathic RBD [ 17 , 18 ], but research on FC in PD-RBD is scarce, and no study to date has explored the structural and functional differences between PD-RBD and PD without RBD (PD-nRBD) in combination with VBM and FC.…”