Brain atrophy in Parkinson's disease with polysomnography-confirmed REM sleep behavior disorder.

We aimed to investigate cortical and subcortical brain alterations in people with Parkinson's disease with polysomnography-confirmed rapid eye movement (REM) sleep behavior disorder (RBD). Thirty people with Parkinson's disease, including 15 people with RBD, were recruited and compared with 41 healthy controls. Surface-based cortical and subcortical analyses were performed on T1-weighted images to investigate thickness and shape abnormalities between groups, and voxel-based and deformation-based morphometry were performed to investigate local volume. Correlations were performed in patients to investigate the structural correlates of motor activity during REM sleep. People with RBD showed cortical thinning in the right perisylvian and inferior temporal cortices and shape contraction in the putamen compared with people without RBD. Compared with controls, people with RBD had extensive cortical thinning and volume loss, brainstem volume was reduced, and shape contraction was found in the basal ganglia and hippocampus. In comparison to controls, people without RBD showed more restricted thinning in the sensorimotor, parietal, and occipital cortices, reduced volume in the brainstem, temporal and more posterior areas, and shape contraction in the pallidum and hippocampus. In Parkinson's disease, higher tonic and phasic REM sleep motor activity was associated with contraction of the thalamic surface, extensive cortical thinning, and subtle volume reduction in the middle temporal gyrus. In Parkinson's disease, the presence of RBD is associated with extensive cortical and subcortical abnormalities, suggesting more severe neurodegeneration in people with RBD. This provides potential neuroanatomical correlates for the more severe clinical phenotype reported in people with Parkinson's disease with RBD.

Gray matter substrates of depressive and anxiety symptoms in idiopathic REM sleep behavior disorder.

INTRODUCTION: Idiopathic rapid eye movement sleep behavior disorder (iRBD) is a prodromal stage of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Depressive and anxiety symptoms are frequent features of PD, DLB and iRBD, and some studies suggest that depressive symptoms are a marker for neurodegeneration in iRBD. However, the pathophysiology of depressive and anxiety symptoms in iRBD is still unclear. This study aimed to investigate cortical and subcortical gray matter (GM) volume substrates of depressive and anxiety symptoms in iRBD patients. METHODS: Forty-six polysomnography-confirmed iRBD patients and 31 healthy controls (HC) without cognitive or mood impairment were recruited. All participants underwent 3-T magnetic resonance imaging and completed the Beck Depression Inventory Second Edition (BDI-II) and Beck Anxiety Inventory (BAI) questionnaires. Voxel-based morphometry analysis was performed to assess GM volume in cortical and subcortical structures. Between-group comparisons and regressions were performed. RESULTS: iRBD patients with depressive symptoms (BDI-II score > 13 or the use of antidepressants to treat depression) showed reduced GM volume in the caudate nucleus compared to HC and iRBD patients without depressive symptoms. Moreover, iRBD patients with anxiety symptoms (BAI score > 9 or the use of anxiolytics to treat anxiety) showed reduced GM volume in the left amygdala extending to the hippocampus compared to HC and iRBD patients without anxiety symptoms. In iRBD patients, higher BDI-II and BAI total scores were associated with lower GM volumes in these regions respectively. CONCLUSION: Depressive and anxiety symptoms in iRBD patients are related to patterns of cortical and subcortical GM volume loss.

Neuroimaging of Rapid Eye Movement Sleep Behavior Disorder.

Idiopathic rapid eye movement sleep behavior disorder (iRBD) is a parasomnia characterized by the loss of muscle atonia and the presence of undesirable motor manifestations during rapid eye movement sleep. Research findings have shown that iRBD is a prodromal stage of synucleinopathies such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. A wide array of neuroimaging techniques have improved our understanding of the prodromal stage of these diseases in patients with iRBD, and identified potential biomarkers. In this chapter, we summarize current knowledge about functional and structural central and peripheral neuroimaging in iRBD, including cross-sectional and longitudinal studies using positron emission tomography, single-photon emission computed tomography, magnetic resonance imaging, and transcranial sonography. Current neuroimaging research has revealed several brain alterations in iRBD similar to those reported in synucleinopathies, thereby improving our understanding of the pathophysiology underlying the clinical presentation and progression of their prodromal stages. Moreover, some abnormalities detected by neuroimaging show promise as potential biomarkers to predict which individuals with iRBD may be at risk of conversion and therefore candidates for inclusion in future clinical trials of neuroprotection.

Cortical and subcortical gray matter bases of cognitive deficits in REM sleep behavior disorder.

OBJECTIVE: To investigate cortical and subcortical gray matter abnormalities underlying cognitive impairment in patients with REM sleep behavior disorder (RBD) with or without mild cognitive impairment (MCI). METHODS: Fifty-two patients with RBD, including 17 patients with MCI, were recruited and compared to 41 controls. All participants underwent extensive clinical assessments, neuropsychological examination, and 3-tesla MRI acquisition of T1 anatomical images. Vertex-based cortical analyses of volume, thickness, and surface area were performed to investigate cortical abnormalities between groups, whereas vertex-based shape analysis was performed to investigate subcortical structure surfaces. Correlations were performed to investigate associations between cortical and subcortical metrics, cognitive domains, and other markers of neurodegeneration (color discrimination, olfaction, and autonomic measures). RESULTS: Patients with MCI had cortical thinning in the frontal, cingulate, temporal, and occipital cortices, and abnormal surface contraction in the lenticular nucleus and thalamus. Patients without MCI had cortical thinning restricted to the frontal cortex. Lower patient performance in cognitive domains was associated with cortical and subcortical abnormalities. Moreover, impaired performance on olfaction, color discrimination, and autonomic measures was associated with thinning in the occipital lobe. CONCLUSIONS: Cortical and subcortical gray matter abnormalities are associated with cognitive status in patients with RBD, with more extensive patterns in patients with MCI. Our results highlight the importance of distinguishing between subgroups of patients with RBD according to cognitive status in order to better understand the neurodegenerative process in this population.

Abnormal Gray Matter Shape, Thickness, and Volume in the Motor Cortico-Subcortical Loop in Idiopathic Rapid Eye Movement Sleep Behavior Disorder: Association with Clinical and Motor Features.

Idiopathic rapid eye movement sleep behavior disorder (iRBD) is a major risk factor for Parkinson's disease and dementia with Lewy bodies. Anatomical gray matter abnormalities in the motor cortico-subcortical loop areas remain under studied in iRBD patients. We acquired T1-weighted images and administrated quantitative motor tasks in 41 patients with polysomnography-confirmed iRBD and 41 healthy subjects. Cortical thickness and voxel-based morphometry (VBM) analyses were performed to investigate local cortical thickness and gray matter volume changes, vertex-based shape analysis to investigate shape of subcortical structures, and structure-based volumetric analyses to investigate volumes of subcortical and brainstem structures. Cortical thickness analysis revealed thinning in iRBD patients in bilateral medial superior frontal, orbitofrontal, anterior cingulate cortices, and the right dorsolateral primary motor cortex. VBM results showed lower gray matter volume in iRBD patients in the frontal lobes, anterior cingulate gyri, and caudate nucleus. Shape analysis revealed extensive surface contraction in the external and internal segments of the left pallidum. Clinical and motor impaired features in iRBD were associated with anomalies of the motor cortico-subcortical loop. In summary, iRBD patients showed numerous gray matter structural abnormalities in the motor cortico-subcortical loop, which are associated with lower motor performance and clinical manifestations of iRBD.

REM Sleep Behavior Disorder and Cognitive Impairment in Parkinson's Disease.

Study Objectives: REM sleep behavior disorder (RBD) is a parasomnia affecting 33% to 46% of patients with Parkinson's disease (PD). The existence of a unique and specific impaired cognitive profile in PD patients with RBD is still controversial. We extensively assessed cognitive functions to identify whether RBD is associated with more severe cognitive deficits in nondemented patients with PD. Methods: One hundred sixty-two participants, including 53 PD patients with RBD, 40 PD patients without RBD, and 69 healthy subjects, underwent polysomnography, a neurological assessment and an extensive neuropsychological exam to assess attention, executive functions, episodic learning and memory, visuospatial abilities, and language. Results: PD patients with RBD had poorer and clinically impaired performance in several cognitive tests compared to PD patients without RBD and healthy subjects. These two latter groups were similar on all cognitive measures. Mild cognitive impairment (MCI) diagnosis frequency was almost threefold higher in PD patients with RBD compared to PD patients without RBD (66% vs. 23%, p < .001). Moreover, subjective cognitive decline was reported in 89% of PD patients with RBD compared to 58% of PD patients without RBD (p = .024). Conclusions: RBD in PD is associated with a more impaired cognitive profile and higher MCI diagnosis frequency, suggesting more severe and widespread neurodegeneration. This patient subgroup and their caregivers should receive targeted medical attention to better detect and monitor impairment and to enable the development of management interventions for cognitive decline and its consequences.