Sleep disturbances and gastrointestinal dysfunction are associated with thalamic atrophy in Parkinson's disease

Regional shape alteration of left thalamus associated with late chronotype in young adults

Chronotype reflects individual differences in circadian rhythms and influences individual psychology and behavior. Previous studies found altered subcortical structures are closely related to individual chronotypes. However, these studies have been conducted mainly using voxel-based morphometry and traditional volume measurement methods with certain limitations. This study aimed to investigate subcortical aberrant volume and shape patterns in late chronotypes (LC) young adults compared to early chronotypes (EC) young adults. Magnetic resonance imaging (MRI) scanning and chronotype assessment were performed once for all participants, including 49 LC young adults and 49 matched EC young adults. The morningness and eveningness preferences were assessed using the Chronotype Questionnaire. A vertex-wise shape analysis was conducted to analyze structural MRI data. There were no significant differences in brain tissue volume and subcortical structural volume between groups. LC young adults showed significant regional shape atrophy in the left ventral posterior thalamus compared to EC individuals. A significant correlation was found between the regional shape atrophy of left ventral posterior thalamus and the score of Chronotype Questionnaire in LC young adults. Regional shape alteration of left thalamus was closely related to the chronotype, and LC may be a potential risk factor for sleep-related behavioral and mental problems in young adults. However, the predominantly female sample and the failure to investigate the effect of chronotype on the subcortical structure-function network are limitations of this study. Further prospective studies are needed to investigate the temporal characteristics of thalamic shape changes and consequent behavioral and psychiatric problems in adults with LC.

Morphological changes in Parkinson's disease based on magnetic resonance imaging: A mini-review of subcortical structures segmentation and shape analysis

Parkinson's disease (PD) is a neurodegenerative disorder caused by the loss of dopaminergic neurons in the substantia nigra, resulting in clinical symptoms, including bradykinesia, resting tremor, rigidity, and postural instability. The pathophysiological changes in PD are inextricably linked to the subcortical structures. Shape analysis is a method for quantifying the volume or surface morphology of structures using magnetic resonance imaging. In this review, we discuss the recent advances in morphological analysis techniques for studying the subcortical structures in PD in vivo. This approach includes available pipelines for volume and shape analysis, focusing on the morphological features of volume and surface area.

Deciphering the Network Effects of Deep Brain Stimulation in Parkinson's Disease

INTRODUCTION

Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy for Parkinson's disease (PD). However, a more detailed characterization of the targeted network and its grey matter (GM) terminals that drive the clinical outcome is needed. In this direction, the use of MRI after DBS surgery is now possible due to recent advances in hardware, opening a window for the clarification of the association between the affected tissue, including white matter fiber pathways and modulated GM regions, and the DBS-related clinical outcome. Therefore, we present a computational framework for reconstruction of targeted networks on postoperative MRI.

METHODS

We used a combination of preoperative whole-brain T1-weighted (T1w) and diffusion-weighted MRI data for morphometric integrity assessment and postoperative T1w MRI for electrode reconstruction and network reconstruction in 15 idiopathic PD patients. Within this framework, we made use of DBS lead artifact intensity profiles on postoperative MRI to determine DBS locations used as seeds for probabilistic tractography to cortical and subcortical targets within the motor circuitry. Lastly, we evaluated the relationship between brain microstructural characteristics of DBS-targeted brain network terminals and postoperative clinical outcomes.

RESULTS

The proposed framework showed robust performance for identifying the DBS electrode positions. Connectivity profiles between the primary motor cortex (M1), supplementary motor area (SMA), and DBS locations were strongly associated with the stimulation intensity needed for the optimal clinical outcome. Local diffusion properties of the modulated pathways were related to DBS outcomes. STN-DBS motor symptom improvement was highly associated with cortical thickness in the middle frontal and superior frontal cortices, but not with subcortical volumetry.

CONCLUSION

These data suggest that STN-DBS outcomes largely rely on the modulatory interference from cortical areas, particularly M1 and SMA, to DBS locations.

Thalamic shape abnormalities in patients with multiple sclerosis-related fatigue

Thalamus plays an important role in the pathogenesis of multiple sclerosis-related fatigue (MSrF). However, the thalamus is a heterogeneous structure and the specific thalamic subregions that are involved in this condition are unclear. Here, we used thalamic shape analysis for the detailed localization of thalamic abnormalities in MSrF. Using the Modified Fatigue Impact Scale, we measured fatigue in 42 patients with relapsing-remitting multiple sclerosis (MS). The thalamic shape was extracted from T1w images using an automated pipeline. We investigated the association of thalamic surface deviations with the severity of global fatigue and its cognitive, physical and psychosocial subdomains. Cognitive fatigue was correlated with an inward deformity of the left anteromedial thalamic surface, but no other localized shape deviation was observed in correlation with global, physical or psychosocial fatigue. Our findings indicate that the left anteromedial thalamic subregions are implicated in cognitive fatigue, possibly through their role in reward processing and cognitive and executive functions.

Therapy of Parkinson's Disease Subtypes

Early descriptions of subtypes of Parkinson's disease (PD) are dominated by the approach of predetermined groups. Experts defined, from clinical observation, groups based on clinical or demographic features that appeared to divide PD into clinically distinct subsets. Common bases on which to define subtypes have been motor phenotype (tremor dominant vs akinetic-rigid or postural instability gait disorder types), age, nonmotor dominant symptoms, and genetic forms. Recently, data-driven approaches have been used to define PD subtypes, taking an unbiased statistical approach to the identification of PD subgroups. The vast majority of data-driven subtyping has been done based on clinical features. Biomarker-based subtyping is an emerging but still quite undeveloped field. Not all of the subtyping methods have established therapeutic implications. This may not be surprising given that they were born largely from clinical observations of phenotype and not in observations regarding treatment response or biological hypotheses. The next frontier for subtypes research as it applies to personalized medicine in PD is the development of genotype-specific therapies. Therapies for GBA-PD and LRRK2-PD are already under development. This review discusses each of the major subtyping systems/methods in terms of its applicability to therapy in PD, and the opportunities and challenges designing clinical trials to develop the evidence base for personalized medicine based on subtypes.

Parkinson's disease and osteoporosis: basic and clinical implications

Introduction: Parkinson's disease (PD) is the second most frequent neurodegenerative disease. Lewy bodies, the hallmark of this disease due to an accumulation of α-synuclein, lead to loss of dopamine-regulated motor circuits, concomitantly progressive immobilization and a broad range of nonmotor features. PD patients have more hospitalizations, endure longer recovery time from comorbidities, and exhibit higher mortality than healthy controls. Although often overlooked, secondary osteoporosis has been reported frequently and is associated with a worse prognosis.Areas covered: In this review, we discuss the pathophysiology of PD from a systemic perspective. We searched on PubMed articles from the last 20 years in PD, both clinical features and bone health status. We discuss possible neuro/endocrine mechanisms by which PD impacts the skeleton, review available therapy for osteoporotic fractures and highlight evidence gaps in defining skeletal co-morbid events.Expert opinion: Future research is essential to understand the local and systemic effects of dopaminergic signaling on bone remodeling and to determine how pathological α-synuclein deposition in the central nervous system might impact the skeleton. It is hoped that a systematic approach to the pathogenesis of this disease and its treatment will allow the informed use of osteoporotic drugs to prevent fractures in PD patients.

Effects of a community-based exercise program on mobility, balance, cognition, sleep, activities of daily living, and quality of life in PD: a pilot study

Aim: The primary objective of the study was to evaluate the effects of a community-based exercise program for adults with Parkinson's disease (PD). Patients & methods: This one-group pretest and post-test design involved 22 participants with PD who participated in two to three exercise sessions per week for 8 weeks. Outcomes assessed for statistical significance included balance, mobility, cognition, activities of daily living, sleep and quality of life. Results: Although exercise is positively correlated with improvements in function, this short-duration study did not demonstrate this. Qualitative themes revealed an increase in self-perceived socialization, coordination and motivation to continue exercise. Conclusion: This community-based exercise study showed improvements in socialization, self-reported coordination and motivation to exercise. Further research is needed to assess community exercise interventions for PD.