Effects of dual-task training on gait and motor ability in patients with Parkinson's disease: A systematic review and meta-analysis.

OBJECTIVE: Parkinson's disease is one of the most common neurodegenerative diseases in the world, which seriously damages motor and balance ability. Dual-task training is discussed as an appropriate intervention. The aim of this review was to synthesize the existing research findings on the efficacy of dual-task training for people with Parkinson's disease. DATA RESOURCES: A systematic search on PubMed, CENTRAL, Embase, Web of Science, and PEDro, randomized-controlled trials (RCTs) of dual-task training for individuals with Parkinson's disease. METHODS: Articles published until 1 November 2022 were included. Our search identified 7 RCTs with a total of 406 subjects. Review Manager 5.4 software was used for bias evaluation and to process the results of the outcome measures collected from the investigations. RESULTS: Dual-task training was associated with significant improvement in most motor and balance outcomes including gait velocity (standard mean difference (SMD) = 0.62; 95% CI, 0.37-0.87; I2 = 31%; P = 0.21), cadence (SMD = 0.29; 95% CI, 0.05-0.53; I2 = 0%; P = 0.71), timed-up-and-go test (mean difference (MD) = -2.38; 95% CI, -3.93 to -0.84; I2 = 32%; P = 0.22) and mini-balance evaluation systems test (MD = 2.04; 95% CI, 1.05-3.03; I2 = 0%; P = 0.92). CONCLUSION: Evidence from meta-analyses suggests that dual-task training may improve motor and balance abilities in Parkinson's disease patients. Future research should focus on finding the most appropriate dual-task treatment model for patients with different degrees, in order to further improve the rehabilitation treatment of Parkinson's disease.

The Role of Blood-Brain Barrier Dysfunction in Mild Cognitive Impairment: a Scientometric and Visualization Analysis from 2000 to 2021.

Mild cognitive impairment (MCI) is a pathological stage between normal cognitive aging and dementia. The blood-brain barrier (BBB) breakdown is emerging as an early biomarker of MCI. This study aimed to visually analyze the literatures related to MCI caused by BBB dysfunction in recent 20 years, systematically identify collaboration networks, track research trends, highlight current hot spots, and predict future frontiers in this field. The related literatures published from 2000 to 2021 were obtained from the Web of Science with the search term "mild cognitive impairment and (blood-brain barrier or neurovascular unit or neurovascular coupling)". VOSviewer software was used to present knowledge map, CiteSpace software was used to extract literature information and make tables, including the top most influential countries, authors, institutions, periodicals, keywords, and references. A total of 333 literatures were used for visual analysis. After 2013, the literatures in the field of BBB dysfunction-induced MCI showed an increased trend in terms of year of publication and quantity of material, with more than 40 publications published each year. USA, England, China, and Sweden cooperated closely. In terms of institutions, Harvard Med Sch ranked first in the number of papers published, followed by Mstricht Univ and Univ Washington. In terms of journals, three of the top five co-cited journals belonged to USA, the other two journals were Neurobiol Aging and J Alzheimers DIS, which were from England and Netherlands respectively. A total of 1752 authors were identified, with Abhay P Sagare the most published and Zlokovic BV the most cited. Keyword emergence detection analysis showed that inflammation, oxidative stress, and memory were new research hot spot in this field. Overall, the research on BBB dysfunction-induced MCI is booming. In the future, cooperation and communication between different countries and institutions should be strengthened.

Bibliometric Analysis Study on the Mechanisms of Brain Energy Metabolism Disorders in Alzheimer's Disease From 2000 to 2020.

Alzheimer's disease (AD) is currently one of the main diseases afflicting the elderly in the world. In recent years, more and more studies have shown that brain energy metabolism disorders are the key pathogenic factors and main early pathological features of AD. Many risk factors such as insulin resistance, mitochondrial dysfunction, oxidative stress, Aß-amyloid plaques, neurofibrillary tangles of hyperphosphorylated tau, aging, and neuroinflammation are involved in brain energy metabolism disorders. In this study, 1,379 Web of Science publications on the mechanisms of brain energy metabolism disorders in AD, all published from 2000 to 2020, were analyzed. Some network maps were drawn using CiteSpace and VOSviewer software which can be used to clarify research focus, forecast research frontiers and development trends, and provide different perspectives and characteristics in AD brain energy metabolism disorder mechanisms.

Invasive behaviour under competition via a free boundary model: a numerical approach.

What will happen when two invasive species are competing and invading the environment at the same time? In this paper, we try to find all the possible scenarios in such a situation based on the diffusive Lotka-Volterra competition system with free boundaries. In a recent work, Du and Wu (Calc Var Partial Differ Equ, 57(2):52, 2018) considered a weak-strong competition case of this model (with spherical symmetry) and theoretically proved the existence of a "chase-and-run coexistence" phenomenon, for certain parameter ranges when the initial functions are chosen properly. Here we use a numerical approach to extend the theoretical research of Du and Wu (Calc Var Partial Differ Equ, 57(2):52, 2018) in several directions. Firstly, we examine how the longtime dynamics of the model changes as the initial functions are varied, and the simulation results suggest that there are four possible longtime profiles of the dynamics, with the chase-and-run coexistence the only possible profile when both species invade successfully. Secondly, we show through numerical experiments that the basic features of the model appear to be retained when the environment is perturbed by periodic variation in time. Thirdly, our numerical analysis suggests that in two space dimensions the population range and the spatial population distribution of the successful invader tend to become more and more circular as time increases no matter what geometrical shape the initial population range possesses. Our numerical simulations cover the one space dimension case, and two space dimension case with or without spherical symmetry. The numerical methods here are based on that of Liu et al. (Mathematics, 6(5):72, 2018, Int J Comput Math, 97(5): 959-979, 2020). In the two space dimension case without radial symmetry, the level set method is used, while the front tracking method is used for the remaining cases. We hope the numerical observations in this paper can provide further insights to the biological invasion problem, and also to future theoretical investigations. More importantly, we hope the numerical analysis may reach more biologically oriented experts and inspire applications of some refined versions of the model tailored to specific real world biological invasion problems.

The Fisher-KPP equation over simple graphs: varied persistence states in river networks.

In this article, we study the dynamical behaviour of a new species spreading from a location in a river network where two or three branches meet, based on the widely used Fisher-KPP advection-diffusion equation. This local river system is represented by some simple graphs with every edge a half infinite line, meeting at a single vertex. We obtain a rather complete description of the long-time dynamical behaviour for every case under consideration, which can be classified into three different types (called a trichotomy), according to the water flow speeds in the river branches, which depend crucially on the topological structure of the graph representing the local river system and on the cross section areas of the branches. The trichotomy includes two different kinds of persistence states, and the state called "persistence below carrying capacity" here appears new.

Revisiting the Fisher-Kolmogorov-Petrovsky-Piskunov equation to interpret the spreading-extinction dichotomy.

The Fisher-Kolmogorov-Petrovsky-Piskunov model, also known as the Fisher-KPP model, supports travelling wave solutions that are successfully used to model numerous invasive phenomena with applications in biology, ecology and combustion theory. However, there are certain phenomena that the Fisher-KPP model cannot replicate, such as the extinction of invasive populations. The Fisher-Stefan model is an adaptation of the Fisher-KPP model to include a moving boundary whose evolution is governed by a Stefan condition. The Fisher-Stefan model also supports travelling wave solutions; however, a key additional feature of the Fisher-Stefan model is that it is able to simulate population extinction, giving rise to a spreading-extinction dichotomy. In this work, we revisit travelling wave solutions of the Fisher-KPP model and show that these results provide new insight into travelling wave solutions of the Fisher-Stefan model and the spreading-extinction dichotomy. Using a combination of phase plane analysis, perturbation analysis and linearization, we establish a concrete relationship between travelling wave solutions of the Fisher-Stefan model and often-neglected travelling wave solutions of the Fisher-KPP model. Furthermore, we give closed-form approximate expressions for the shape of the travelling wave solutions of the Fisher-Stefan model in the limit of slow travelling wave speeds, c≪1.

Spreading speed for a West Nile virus model with free boundary.

The purpose of this paper is to determine the precise asymptotic spreading speed of the virus for a West Nile virus model with free boundary, introduced recently in Lin and Zhu (J Math Biol 75:1381-1409, 2017), based on a model of Lewis et al. (Bull Math Biol 68:3-23, 2006). We show that this speed is uniquely defined by a semiwave solution associated with the West Nile virus model. To find such a semiwave solution, we firstly consider a general cooperative system over the half-line [Formula: see text], and prove the existence of a monotone solution by an upper and lower solution approach; we then establish the existence and uniqueness of the desired semiwave solution by applying this method together with some other techniques including the sliding method. Our result indicates that the asymptotic spreading speed of the West Nile virus model with free boundary is strictly less than that of the corresponding model in Lewis et al. (2006).

Free boundary models for mosquito range movement driven by climate warming.

As vectors, mosquitoes transmit numerous mosquito-borne diseases. Among the many factors affecting the distribution and density of mosquitoes, climate change and warming have been increasingly recognized as major ones. In this paper, we make use of three diffusive logistic models with free boundary in one space dimension to explore the impact of climate warming on the movement of mosquito range. First, a general model incorporating temperature change with location and time is introduced. In order to gain insights of the model, a simplified version of the model with the change of temperature depending only on location is analyzed theoretically, for which the dynamical behavior is completely determined and presented. The general model can be modified into a more realistic one of seasonal succession type, to take into account of the seasonal changes of mosquito movements during each year, where the general model applies only for the time period of the warm seasons of the year, and during the cold season, the mosquito range is fixed and the population is assumed to be in a hibernating status. For both the general model and the seasonal succession model, our numerical simulations indicate that the long-time dynamical behavior is qualitatively similar to the simplified model, and the effect of climate warming on the movement of mosquitoes can be easily captured. Moreover, our analysis reveals that hibernating enhances the chances of survival and successful spreading of the mosquitoes, but it slows down the spreading speed.