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Neurobiology of Disease Jun 2024Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the...
Human beings are living longer than ever before and aging is accompanied by an increased incidence of motor deficits, including those associated with the neurodegenerative conditions, Parkinson's disease (PD) and Huntington's disease (HD). However, the biological correlates underlying this epidemiological finding, especially the functional basis at the synapse level, have been elusive. This study reveals that motor skill performance examined via rotarod, beam walking and pole tests is impaired in aged mice. This study, via electrophysiology recordings, further identifies an aging-related reduction in the efficacy of inhibitory synaptic transmission onto dorsolateral striatum (DLS) indirect-pathway medium spiny neurons (iMSNs), i.e., a disinhibition effect on DLS iMSNs. In addition, pharmacologically enhancing the activity of DLS iMSNs by infusing an adenosine A receptor (AR) agonist, which presumably mimics the disinhibition effect, impairs motor skill performance in young mice, simulating the behavior in aged naïve mice. Conversely, pharmacologically suppressing the activity of DLS iMSNs by infusing an AR antagonist, in order to offset the disinhibition effect, restores motor skill performance in aged mice, mimicking the behavior in young naïve mice. In conclusion, this study identifies a functional inhibitory synaptic plasticity in DLS iMSNs that likely contributes to the aging-related motor skill deficits, which would potentially serve as a striatal synaptic basis underlying age being a prominent risk factor for neurodegenerative motor deficits.
PubMed: 38942325
DOI: 10.1016/j.nbd.2024.106582 -
Clinical Neurophysiology : Official... Jun 2024Parkinsonian motor symptoms are linked to pathologically increased beta oscillations in the basal ganglia. Studies with externalised deep brain stimulation electrodes...
OBJECTIVE
Parkinsonian motor symptoms are linked to pathologically increased beta oscillations in the basal ganglia. Studies with externalised deep brain stimulation electrodes showed that Parkinson patients were able to rapidly gain control over these pathological basal ganglia signals through neurofeedback. Studies with fully implanted deep brain stimulation systems duplicating these promising results are required to grant transferability to daily application.
METHODS
In this study, seven patients with idiopathic Parkinson's disease and one with familial Parkinson's disease were included. In a postoperative setting, beta oscillations from the subthalamic nucleus were recorded with a fully implanted deep brain stimulation system and converted to a real-time visual feedback signal. Participants were instructed to perform bidirectional neurofeedback tasks with the aim to modulate these oscillations.
RESULTS
While receiving regular medication and deep brain stimulation, participants were able to significantly improve their neurofeedback ability and achieved a significant decrease of subthalamic beta power (median reduction of 31% in the final neurofeedback block).
CONCLUSION
We could demonstrate that a fully implanted deep brain stimulation system can provide visual neurofeedback enabling patients with Parkinson's disease to rapidly control pathological subthalamic beta oscillations.
SIGNIFICANCE
Fully-implanted DBS electrode-guided neurofeedback is feasible and can now be explored over extended timespans.
PubMed: 38941959
DOI: 10.1016/j.clinph.2024.06.001 -
ELife Jun 2024Parkinson's disease (PD) is characterized by motor impairments caused by degeneration of dopamine neurons in the substantia nigra pars compacta. In addition to these...
Parkinson's disease (PD) is characterized by motor impairments caused by degeneration of dopamine neurons in the substantia nigra pars compacta. In addition to these symptoms, PD patients often suffer from non-motor comorbidities including sleep and psychiatric disturbances, which are thought to depend on concomitant alterations of serotonergic and noradrenergic transmission. A primary locus of serotonergic neurons is the dorsal raphe nucleus (DRN), providing brain-wide serotonergic input. Here, we identified electrophysiological and morphological parameters to classify serotonergic and dopaminergic neurons in the murine DRN under control conditions and in a PD model, following striatal injection of the catecholamine toxin, 6-hydroxydopamine (6-OHDA). Electrical and morphological properties of both neuronal populations were altered by 6-OHDA. In serotonergic neurons, most changes were reversed when 6-OHDA was injected in combination with desipramine, a noradrenaline (NA) reuptake inhibitor, protecting the noradrenergic terminals. Our results show that the depletion of both NA and dopamine in the 6-OHDA mouse model causes changes in the DRN neural circuitry.
Topics: Animals; Dopaminergic Neurons; Serotonergic Neurons; Dorsal Raphe Nucleus; Mice; Disease Models, Animal; Oxidopamine; Parkinsonian Disorders; Male; Mice, Inbred C57BL; Desipramine; Norepinephrine
PubMed: 38940422
DOI: 10.7554/eLife.90278 -
Journal of Integrative Neuroscience May 2024The objective of this study is to compare the differences in effective connectivity within the default mode network (DMN) subsystems between patients with Parkinson's...
OBJECTIVE
The objective of this study is to compare the differences in effective connectivity within the default mode network (DMN) subsystems between patients with Parkinson's disease with mild cognitive impairment (PD-MCI) and patients with Parkinson's disease with normal cognition (PD-CN). The mechanisms underlying DMN dysfunction in PD-MCI patients and its association with clinical cognitive function in PD-MCI are aimed to be investigated.
METHODS
The spectral dynamic causal model (spDCM) was employed to analyze the effective connectivity of functional magnetic resonance imaging (fMRI) data in the resting state for the DMN subsystems, which include the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), left and right angular gyrus (LAG, RAG) in 23 PD-MCI and 22 PD-CN patients, respectively. The effective connectivity values of DMN subsystems in the two groups were statistically analyzed using a two-sample -test. The Spearman correlation analysis was used to test the correlation between the effective connectivity values of the subsystems with significant differences between the two groups and the clinical cognitive function (as measured by Montreal Cognitive Assessment Scale (MoCA) score).
RESULTS
Statistical analysis revealed significant differences in the effective connections of MPFC-LAG and LAG-PCC between the two patient groups (MPFC-LAG: t = -2.993, < 0.05; LAG-PCC: t = 2.174, < 0.05).
CONCLUSIONS
The study findings suggest that abnormal strength and direction of effective connections between DMN subsystems are found in PD-MCI patients.
Topics: Humans; Parkinson Disease; Cognitive Dysfunction; Male; Female; Default Mode Network; Magnetic Resonance Imaging; Aged; Middle Aged; Prefrontal Cortex; Gyrus Cinguli; Connectome; Nerve Net
PubMed: 38940086
DOI: 10.31083/j.jin2306110 -
Journal of Integrative Neuroscience May 2024Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta region of... (Review)
Review
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta region of the midbrain and the formation of intracellular protein aggregates known as Lewy bodies, of which a major component is the protein α-synuclein. Several studies have suggested that mitochondria play a central role in the pathogenesis of PD, encompassing both familial and sporadic forms of the disease. Mitochondrial dysfunction is attributed to bioenergetic impairment, increased oxidative stress, damage to mitochondrial DNA, and alteration in mitochondrial morphology. These alterations may contribute to improper functioning of the central nervous system and ultimately lead to neurodegeneration. The perturbation of mitochondrial function makes it a potential target, worthy of exploration for neuroprotective therapies and to improve mitochondrial health in PD. Thus, in the current review, we provide an update on mitochondria-based therapeutic approaches toward α-synucleinopathies in PD.
Topics: Humans; Parkinson Disease; Synucleinopathies; Mitochondria; Animals; alpha-Synuclein
PubMed: 38940084
DOI: 10.31083/j.jin2306109 -
Journal of Integrative Neuroscience Jun 2024Deep brain stimulation (DBS) is a common therapy for managing Parkinson's disease (PD) in clinical practice. However, a complete understanding of its mode of action is... (Review)
Review
Deep brain stimulation (DBS) is a common therapy for managing Parkinson's disease (PD) in clinical practice. However, a complete understanding of its mode of action is still needed. DBS is believed to work primarily through electrical and neurochemical pathways. Furthermore, DBS has other mechanisms of action. This review explores the fundamental concepts and applications of DBS in treating PD, including its mechanisms, clinical implications, and recent research.
Topics: Deep Brain Stimulation; Parkinson Disease; Humans; Brain; Animals
PubMed: 38940083
DOI: 10.31083/j.jin2306114 -
Current Developments in Nutrition Jun 2024This article explores the potential therapeutic implications of phytochemicals on the gut-brain axis (GBA), which serves as a communication network between the central... (Review)
Review
This article explores the potential therapeutic implications of phytochemicals on the gut-brain axis (GBA), which serves as a communication network between the central nervous system and the enteric nervous system. Phytochemicals, which are compounds derived from plants, have been shown to interact with the gut microbiota, immune system, and neurotransmitter systems, thereby influencing brain function. Phytochemicals such as polyphenols, carotenoids, flavonoids, and terpenoids have been identified as having potential therapeutic implications for various neurological disorders. The GBA plays a critical role in the development and progression of various neurological disorders, including Parkinson's disease, multiple sclerosis, depression, anxiety, and autism spectrum disorders. Dysbiosis, or an imbalance in gut microbiota composition, has been associated with a range of neurological disorders, suggesting that modulating the gut microbiota may have potential therapeutic implications for these conditions. Although these findings are promising, further research is needed to elucidate the optimal use of phytochemicals in neurological disorder treatment, as well as their potential interactions with other medications. The literature review search was conducted using predefined search terms such as phytochemicals, gut-brain axis, neurodegenerative, and Parkinson in PubMed, Embase, and the Cochrane library.
PubMed: 38939650
DOI: 10.1016/j.cdnut.2024.103785 -
Parkinson's Disease 2024Postural instability and gait difficulties (PIGD) are a significant cause of falls, mobility loss, and lower quality of life in Parkinson's disease (PD). The connection...
BACKGROUND
Postural instability and gait difficulties (PIGD) are a significant cause of falls, mobility loss, and lower quality of life in Parkinson's disease (PD). The connection between PD progression and diminished strength in the lower limbs has been acknowledged. However, the identification of specific muscle groups linked to PIGD and non-PIGD motor features is still unknown.
OBJECTIVE
To explore the relationship between the strength of specific lower limb muscle groups, along with muscle mass, and their associations with PIGD, PIGD subtypes, and non-PIGD motor features in PD.
METHODS
95 PD participants underwent detailed motor and non-motor test batteries, including lower limb isometric strength testing and whole-body lean mass assessments. Correlation analysis and univariate and multivariate linear/logistic forward stepwise regression were performed to test associations between PIGD and non-PIGD motor features with normalized value (z-score) of lower limb muscle strength and measures of lean mass.
RESULTS
Multivariate regression analysis, adjusted for age, gender, and levodopa equivalent dose, revealed that hip abductor strength was significantly associated with overall PIGD motor severity ratings ( < 0.001), impaired balance ( < 0.001), and non-PIGD Parkinsonian motor features ( < 0.001). Conversely, hip extensor strength was significantly associated with falls, slow walking, and FoG motor features (=0.016; =0.003; =0.020, respectively).
CONCLUSION
We found that lower hip abductor strength was associated with PIGD and non-PIGD motor features. The association between non-PIGD motor features may suggest specific vulnerability of the hip abductors as part of a proposed brain-muscle loop hypothesis in PD. Moreover, lower hip extensor strength correlated with falls, slow walking, and FoG.
PubMed: 38939534
DOI: 10.1155/2024/5580870 -
Parkinson's Disease 2024Fatigue is a common and debilitating symptom affecting a significant proportion of individuals with Parkinson's disease (PD), often overshadowing even motor symptoms in... (Review)
Review
Fatigue is a common and debilitating symptom affecting a significant proportion of individuals with Parkinson's disease (PD), often overshadowing even motor symptoms in its impact on quality of life. The accurate definition and assessment of mental fatigue in PD is crucial for both clinical management and research, yet it remains a challenge due to the subjective nature of the symptom and the heterogeneity of assessment scales. This systematic review examined the existing measures of self-reported mental fatigue in PD by searching through PubMed, Embase, and Scopus databases using specific keywords from 2001 to 2024. Out of the 4182 articles found, 40 met the inclusion criteria, and 14 different scales were identified to measure self-reported fatigue in PD patients. However, most of these scales lack a consistent definition of fatigue, indicating a need for validated combinations of unidimensional and multidimensional scales to accurately assess mental fatigue in PD. The review found that it is best to use Fatigue Severity Inventory (FSI) and Multidimensional Fatigue Inventory (MdFI) to screen for severity of PD mental fatigue and Neuro-QoL Item Bank v1.0 (Neuro-QoL) to evaluate its impact on patients' lives. Furthermore, multidimensional scales Parkinson's Disease Questionnaire (PDQ) and Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT-F) are frequently coupled with Fatigue Severity Scale (FSS), Parkinson's Fatigue Scale (PFS), and/or Modified Fatigue Impact Scale (MFIS) due to their short length and holistic coverage of variables in patients' quality of life. Combining fatigue scales can be used for screening and scoring methods. The review also recommends validating fatigue scales translation and combining them with biomarkers to improve the accuracy and effectiveness of fatigue assessment in clinical practice. Future research should analyze correlations between fatigue scales, expand language types, and explore the link between fatigue scales and the pathophysiological basis of PD. Our findings underscore the need for a standardized approach to the measurement of fatigue in PD and set the stage for future research to consolidate assessment tools that can reliably guide treatment strategies and improve patient outcomes.
PubMed: 38939533
DOI: 10.1155/2024/9614163 -
Journal of Extracellular Biology Nov 2023Parkinsonian disorders, including Parkinson's disease (PD), multiple system atrophy (MSA), dementia with Lewy body (DLB), corticobasal syndrome (CBS) and progressive... (Review)
Review
Parkinsonian disorders, including Parkinson's disease (PD), multiple system atrophy (MSA), dementia with Lewy body (DLB), corticobasal syndrome (CBS) and progressive supranuclear palsy (PSP) are often misdiagnosed due to overlapping symptoms and the absence of precise biomarkers. Furthermore, there are no current methods to ascertain the progression and conversion of prodromal conditions such as REM behaviour disorder (RBD). Extracellular vesicles (EVs), containing a mixture of biomolecules, have emerged as potential sources for parkinsonian diagnostics. However, inconsistencies in previous studies have left their diagnostic potential unclear. We conducted a meta-analysis, following PRISMA guidelines, to assess the diagnostic accuracy of general EVs isolated from various bodily fluids, including cerebrospinal fluid (CSF), plasma, serum, urine or saliva, in differentiating patients with parkinsonian disorders from healthy controls (HCs). The meta-analysis included 21 studies encompassing 1285 patients with PD, 24 with MSA, 105 with DLB, 99 with PSP, 101 with RBD and 783 HCs. Further analyses were conducted only for patients with PD versus HCs, given the limited number for other comparisons. Using bivariate and hierarchal receiver operating characteristics (HSROC) models, the meta-analysis revealed moderate diagnostic accuracy in distinguishing patients with PD from HCs, with substantial heterogeneity and publication bias. The trim-and-fill method revealed at least two missing studies with null or low diagnostic accuracy. CSF-EVs showed better overall diagnostic accuracy, while plasma-EVs had the lowest performance. General EVs demonstrated higher diagnostic accuracy compared to CNS-originating EVs, which are more time-consuming, labour- and cost-intensive to isolate. In conclusion, while holding promise, utilizing biomarkers in general EVs for PD diagnosis remains unfeasible due to existing challenges. The focus should shift toward harmonizing the field through standardization, collaboration, and rigorous validation. Current efforts by the International Society For Extracellular Vesicles (ISEV) aim to enhance the accuracy and reproducibility of EV-related research through rigor and standardization, aiming to bridge the gap between theory and practical clinical application.
PubMed: 38939363
DOI: 10.1002/jex2.121