Resting-state fMRI study on drug-naïve early-stage patients with Parkinson's disease and with fatigue

Disrupted Paraventricular Hypothalamic Nucleus Functional Connectivity in Parkinson's Disease With Constipation

BACKGROUND

Constipation is one of the most common non-motor symptoms in patients with Parkinson's disease (PD), which could manifest during the early stage of the disease. However, the etiology of constipation in PD remains largely unknown. Previous studies supported that gastrointestinal dysfunction may be associated with functional connectivity alterations in paraventricular hypothalamic nucleus (PVN). Therefore, this study aimed to investigate the potential contribution of the PVN to the pathogenesis of constipation in a cohort of early-stage patients with PD and to compare brain network organization between PD patients with and without constipation.

METHODS

A total of 66 PD patients (PD with constipation and without constipation) and 30 healthy controls were prospectively enrolled. All participants acquired T1-weighted and resting-state fMRI scans. Then we employed voxel-based morphometry analysis and functional connectivity analysis.

RESULTS

We observed a decreased functional connectivity in the PVN-pontine tegmentum pathway in PD patients with constipation compared to the patients without constipation (p = 0.006, t = 5.37), while we did not find any changes in basal ganglia circuitry between these two groups. In addition, we found that the functional connectivity between PVN and pontine tegmentum was negatively associated with the UPDRS I, II, III and NMSS scores (p < 0.05). Meanwhile, these two types of patients also showed substantial differences in functional connections linking the inferior frontal gyrus and cerebellum with multiple brain regions. We discovered no statistical difference in gray matter volume among these two groups.

CONCLUSIONS

Our study provides further insights into the dysfunctional mechanisms of constipation, suggesting that abnormal PVN functional connectivity may be related to the mechanism of constipation in PD. Meanwhile, the inferior frontal gyrus and cerebellum may be involved in the occurrence of constipation in PD patients.

Targeting neuroplasticity: a viewpoint on a future research direction with Parkinson's disease-related fatigue

Parkinson's disease-related fatigue has an insidious onset and complex pathomechanisms, causing many adverse effects on patients. In clinical practice, Parkinson's disease-related fatigue has not received sufficient attention, and its early diagnosis and targeted interventions are inadequate. Currently, pharmacological treatments for Parkinson's disease-related fatigue have limited efficacy and nonpharmacological therapies such as non-invasive brain stimulation techniques and exercise therapy have been shown to have a role in improving Parkinson's disease-related fatigue. Further studies have revealed that modulation of functional cortical excitability, induction of neuroplasticity changes, inhibition of oxidative stress, improvement of cardiorespiratory fitness, and enhancement of muscle strength may be potential mechanisms of action of non-pharmacological therapies. As relevant research continues to progress, targeted therapy based on the theory of neuroplasticity may become an important therapeutic idea for Parkinson's disease-related fatigue. This article provides an overview of the diagnosis, etiology, and treatment of Parkinson's disease-related fatigue, and on this basis proposes a new diagnostic and therapeutic idea of targeting neuroplasticity to improve Parkinson's disease-related fatigue for clinical reference. Further studies on the pathological mechanisms of Parkinson's disease-related fatigue are needed in the future to optimize the treatment regimen of Parkinson's disease-related fatigue to improve the efficacy of treatment for the benefit of patients.

The potential use of plasma NfL as a diagnostic and prognostic biomarker of fatigue in early Parkinson's disease

Background

Fatigue is a prevalent non-motor symptom that often appears in the early stages of Parkinson's disease (PD). Plasma neurofilament light chain (NfL) was elevated in PD patients and may be considered a potential biomarker for both motor and cognitive progression.

Objectives

In this study, we explored the association between plasma NfL levels and various fatigue subtypes and the prediction of baseline plasma NfL levels for fatigue subtype conversion.

Methods

Patients with PD were classified into four categories: persistent fatigue, never fatigue, non-persistent fatigue, and new-onset fatigue. They underwent detailed neurological evaluations at baseline and a 2-year follow-up. Plasma NfL, glial fibrillary acidic protein, phosphorylated tau181, amyloid beta 42, and Aβ40 levels in both PD patients and control subjects were measured using an ultrasensitive single molecule array.

Results

The study enrolled 174 PD patients and 95 control subjects. Plasma NfL levels were significantly higher in the persistent fatigue group compared to the never fatigue group at the 2-year follow-up (p < 0.05). Longitudinally, 45.16% of baseline fatigue patients converted to non-fatigue at the 2-year follow-up. Additionally, 22.12% of patients initially without-figure patients converted to fatigue patients at the 2-year follow-up. Baseline plasma NfL levels were significantly higher in both the persistent fatigue and new-onset fatigue groups compared to the never fatigue group (p < 0.05). Higher baseline NfL levels were significantly associated with new-onset fatigue (odds ratio = 1.127, p = 0.034) after adjusting for confounders.

Conclusion

Baseline plasma NfL levels may serve as a biomarker for predicting fatigue subtype conversion and the progression of fatigue in PD.

Challenges and Frontiers in Computational Metabolic Psychiatry

One of the primary challenges in metabolic psychiatry is that the disrupted brain functions that underlie psychiatric conditions arise from a complex set of downstream and feedback processes that span multiple spatiotemporal scales. Importantly, the same circuit can have multiple points of failure, each of which results in a different type of dysregulation, and thus elicits distinct cascades downstream that produce divergent signs and symptoms. Here, we illustrate this challenge by examining how subtle differences in circuit perturbations can lead to divergent clinical outcomes. We also discuss how computational models can perform the spatially heterogeneous integration and bridge in vitro and in vivo paradigms. By leveraging recent methodological advances and tools, computational models can integrate relevant processes across scales (e.g., tricarboxylic acid cycle, ion channel, neural microassembly, whole-brain macrocircuit) and across physiological systems (e.g., neural, endocrine, immune, vascular), providing a framework that can unite these mechanistic processes in a manner that goes beyond the conceptual and descriptive to the quantitative and generative. These hold the potential to sharpen our intuitions toward circuit-based models for personalized diagnostics and treatment.

Genetic analyses identify brain functional networks associated with the risk of Parkinson's disease and drug-induced parkinsonism

Brain functional networks are associated with parkinsonism in observational studies. However, the causal effects between brain functional networks and parkinsonism remain unclear. We aimed to assess the potential bidirectional causal associations between 191 brain resting-state functional magnetic resonance imaging (rsfMRI) phenotypes and parkinsonism including Parkinson's disease (PD) and drug-induced parkinsonism (DIP). We used Mendelian randomization (MR) to assess the bidirectional associations between brain rsfMRI phenotypes and parkinsonism, followed by several sensitivity analyses for robustness validation. In the forward MR analyses, we found that three rsfMRI phenotypes genetically determined the risk of parkinsonism. The connectivity in the visual network decreased the risk of PD (OR = 0.391, 95% CI = 0.235 ~ 0.649, P = 2.83 × 10-4, P_FDR = 0.039). The connectivity of salience and motor networks increased the risk of DIP (OR = 4.102, 95% CI = 1.903 ~ 8.845, P = 3.17 × 10-4, P_FDR = 0.044). The connectivity of limbic and default mode networks increased the risk of DIP (OR = 14.526, 95% CI = 3.130 ~ 67.408, P = 6.32 × 10-4, P_FDR = 0.0437). The reverse MR analysis indicated that PD and DIP had no effect on brain rsfMRI phenotypes. Our findings reveal causal relationships between brain functional networks and parkinsonism, providing important interventional and therapeutic targets for different parkinsonism.

Behavioral disorders in Parkinson disease: current view

Patients with Parkinson disease (PD) frequently experience several behavioral symptoms, such as anxiety, apathy, irritability, agitation, impulsive control and obsessive-compulsive or REM sleep behavior disorders, which can cause severe psychosocial problems and impair quality of life. Occurring in 30-70% of PD patients, these symptoms can manifest at early stages of the disease, sometimes even before the appearance of classic motor symptoms, while others can develop later. Behavioral changes in PD show distinct patterns of brain atrophy, dopaminergic and serotonergic deterioration, altered neuronal connectivity in frontostriatal, corticolimbic, default mode and other networks due to a cascade linking molecular pathologies and deficits in multiple behavior domains. The changes suggest a multi-system neurodegenerative process in the context of a specific α-synucleinopathy inducing a variety of biochemical and functional changes, the neurobiological basis and clinical relevance of which await further elucidation. This paper is intended to review the recent literature with focus on the main behavioral disturbances in PD patients, their epidemiology, clinical features, risk factors, animal models, neuroimaging findings, pathophysiological backgrounds, and treatment options of these deleterious lesions.

Decreases in frequency-dependent intrinsic activity of the default mode network are associated with depression and cognition in patients with postacute sequelae of SARS-CoV-2 infection

A significant proportion of patients who have recovered from COVID-19 suffer from persistent symptoms, referred to as "post-acute sequelae of SARS-CoV-2 infection (PASC)". Abnormal brain intrinsic activity has been observed in PASC patients, but the patterns of frequency-dependent intrinsic activity in the PASC and non-PASC (recovered COVID-19 patients without persistent symptoms) groups and their association with neuropsychiatric sequelae remain unclear in PASC. Twenty-nine PASC patients, 27 non-PASC subjects, and 31 healthy controls (HCs) were recruited. The voxel-level fractional amplitude of low-frequency fluctuation (fALFF) was calculated in different frequency bands (typical frequency band: 0.01-0.10 Hz; slow 5: 0.01-0.023 Hz; slow 4: 0.023-0.073 Hz) to assess regional intrinsic activity patterns within different groups. Correlation analyses were performed to explore the associations between frequency-dependent alterations and clinical variables. Significant frequency-dependent alterations in intrinsic activity patterns were observed in both the PASC and non-PASC groups, primarily involving regions of the default mode network (DMN). The decreased fALFF values of the DMN in different frequency bands were associated with different symptoms in PASC. For example, decreased fALFF in the left precuneus in the typical frequency band was related to general attention impairment in PASC, whereas decreased fALFF in the left superior frontal gyrus appeared in non-PASC. The fALFF alterations in the left precuneus/posterior cingulate gyrus in the slow 5 band were also related to cognitive performance in PASC. Additionally, in the slow 4 band, decreased fALFF in the right angular gyrus was associated with depressive symptoms in the PASC. Our results may provide insights into the potential neural mechanisms underlying symptoms in PASC patients.

Disease-State Dependent Associations Between Intrinsic Brain Function and Symptoms of Fatigue, Depression, and Anxiety in Crohn's Disease

BACKGROUND

Extraintestinal symptoms (EIS) in inflammatory bowel diseases, including fatigue, depression and anxiety, are highly prevalent, but poorly understood. Alterations of brain function may contribute to EIS, but their association with disease activity is unclear. This study analyzed intrinsic neural activity (INA) of individuals with Crohn's disease (CD) in different disease states and examined the relationship between INA and EIS.

METHODS

Patients with CD (n = 92) and healthy controls (n = 41) underwent functional magnetic resonance brain imaging and completed symptom-specific psychometry. Temporal (amplitude of low-frequency fluctuations, ALFF) and spatial (regional homogeneity, ReHo) markers of INA were compared between CD and controls and between active (patients with active Crohn's disease [aCD]) versus remitted (rCD) disease. Regression analyses explored disease-state-dependent associations between INA and EIS.

RESULTS

Patients exhibited aberrant INA in frontotemporal, occipital, and thalamic regions. Patients with aCD exhibited lower ALFF in left subcallosal cortex and inferior temporal gyri compared to rCD. Regional homogeneity in aCD was lower in left medial orbital gyrus and higher in right superior frontal, left inferior temporal, and left precentral gyrus. Compared to rCD, aCD showed higher ALFF predominantly in superior, ventro-, and dorsolateral prefrontal regions. Distinct associations between INA and EIS were detected in patients, particularly in the remitted state.

CONCLUSIONS

Intrinsic brain function in patients with CD varies by disease state, with prominent frontal cortex changes in active disease. These brain activity changes are at least partly related to the magnitude of neuropsychiatric symptoms and highlight a role of disturbed brain-gut interactions in the development of EIS especially in rCD.

Sympathetic dysfunction as an early indicator of autonomic involvement in Parkinson's disease

PURPOSE

The specific characteristics of autonomic involvement in patients with early Parkinson's disease (PD) are unclear. This study aimed to evaluate the characteristics of autonomic dysfunction in drug-naïve patients with early-stage PD without orthostatic hypotension (OH) by analyzing Valsalva maneuver (VM) parameters.

METHODS

We retrospectively analyzed drug-naïve patients without orthostatic hypotension (n = 61) and controls (n = 20). The patients were subcategorized into early PD (n = 35) and mid-PD (n = 26) groups on the basis of the Hoehn and Yahr staging. VM parameters, including changes in systolic blood pressure at late phase 2 (∆SBPVM2), ∆HRVM3, Valsalva ratio (VR), pressure recovery time, adrenergic baroreflex sensitivity, and vagal baroreflex sensitivity, were assessed.

RESULTS

In the early PD group, ∆SBPVM2, a marker of sympathetic function, was significantly lower compared with that in controls (risk ratio = 0.95, P = 0.027). Receiver operating characteristic (ROC) curve analysis showed an optimal cut-off value of -10 mmHg for ∆SBPVM2 [P = 0.002, area under the curve (AUC): 0.737]. VR exhibited an inverse relationship with Unified Parkinson's Disease Rating Scale Part 3 scores in the multivariable regression analysis (VR: P = 0.038, β = -28.61), whereas age showed a positive relationship (age: P = 0.027, β = 0.35).

CONCLUSION

The ∆BPVM2 parameter of the VM may help detect autonomic nervous system involvement in early-PD without OH. Our results suggest that sympathetic dysfunction is an early manifestation of autonomic dysfunction in patients with PD.

The effect of Parkin gene S/N 167 polymorphism on resting spontaneous brain functional activity in Parkinson's Disease

BACKGROUND

Genetic susceptibility plays a significant role in Parkinson's disease (PD) development. Carriers of the Parkin S/N167 mutation may have an increased risk of PD and altered spontaneous brain activity.

OBJECTIVE

This study aims to investigate the potential pathogenesis of PD through a comparative analysis of the amplitude of low-frequency fluctuations (ALFF) in resting-state functional magnetic resonance imaging (rs-fMRI) of subjects with Parkin gene S/N 167 polymorphisms, and to examine the association between spontaneous brain activity and clinical scale scores of PD.

METHODS

A total of 69 PD patients and 84 healthy controls (HC) were included in the study. Each subject was genotyped for the Parkin gene S/N 167 polymorphism and underwent rs-fMRI scans. ALFF analysis was employed to evaluate the relationship among genotypes, interactive brain regions, and clinical symptoms in PD.

RESULTS

PD patients exhibited decreased ALFF values in the right anterior lobe and vermis of the cerebellum compared to HC. No significant interaction was found between the gene's main effect and the "group × genotype" effect on brain ALFF values. One-factor ANOVA revealed no significant difference in ALFF values between PD subgroups; however, the ALFF values in the right anterior lobe and vermis of the cerebellum were lower in the PD-G and PD-GA groups compared to the HC-G and HC-GA groups. Spearman correlation analysis demonstrated that ALFF values in the PD-GG and PD-GA groups were negatively associated with UPDRS-III scores in the bilateral lingual gyrus (Lingual R/L).

CONCLUSION

Parkin gene S/N 167 polymorphisms may influence brain functional activity in specific brain regions, and ALFF values are associated with motor symptoms in PD patients.