The effects of treadmill exercise in animal models of Parkinson's disease: A systematic review

Treadmill exercise mitigates rotenone-induced neuroinflammation and α-synuclein level in a mouse model of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting 7-10 million people globally. It presents with motor symptoms like bradykinesia, tremors, rigidity, and postural instability, along with non-motor issues such as anxiety and mood fluctuations. PD is characterized by the progressive loss of nigrostriatal neurons, α-synuclein protein aggregation, reduced tyrosine hydroxylase level, and impaired dopamine signaling. Neuroinflammation plays a key role in PD progression, with elevated pro-inflammatory cytokines promoting M1 microglial activation, which exacerbates neurodegeneration. Conversely, anti-inflammatory cytokines such as IL-10 and IL-4 help shift microglia to the neuroprotective M2 phenotype, reducing inflammation. Animal models show an imbalance with increased M1 and reduced M2 microglia. This study explored the neuroprotective effects of treadmill exercise in a rotenone-induced PD mouse model. After 21 days of exercise, behavioral impairments improved, as shown by open field tests, Rota-rod, and footprint analysis. Exercise also reduced pro-inflammatory cytokines; TNF-α, and IL-1β levels while increasing anti-inflammatory cytokines; IL-10, and IL-4. This shift correlated with decreased α-synuclein levels and increased tyrosine hydroxylase expression, indicating reduced neurodegeneration. These findings suggest that treadmill exercise can mitigate PD symptoms and pathology by modulating neuroinflammation and restoring dopaminergic function.

Is Mat pilates effective in lower limb strength and hand grip strength of people with Parkinson's? A randomized clinical trial with follow-up

INTRODUCTION

Parkinson's disease can contribute to the loss of muscle strength, and physical exercise such as Mat Pilates can be effective in improving this, core stability, flexibility, and muscle control.

OBJECTIVE

To analyze the effects of a 12-week intervention with Mat Pilates in the short and long term, on lower limb and hand grip strength in people with Parkinson's.

METHODS

The study included 23 people (61.7 ± 7.5 years) of both sexes, diagnosed with Parkinson's disease who were selected according to inclusion criteria and divided into intervention and control groups.

RESULTS

The hand grip variable showed improvement in the intervention group intragroup only in the right hand (p = 0.003) in the post-intervention period. In the lower limb strength variable, there was significance in the extension of the left leg both in the intervention intragroup (p = 0.042), and in the control group (p = 0.001) the result in the flexion of the left leg in the intervention group (p = 0.032). The follow-up data showed significance in the strength of extension of the right leg in the intervention group (p = 0.049) and in the control group (p = 0.024) and in the extension of the left leg in the intervention group (p = 0.021).

CONCLUSION

Mat Pilates classes for people with Parkinson's with mild and moderate degrees proved to be effective in the short term in the hand grip strength of the right hand, and in the extension and flexion of the left legs, and positive effects in the long term in the strength of extension of the right also left legs.

Physiological change of striatum and ventral midbrain's glia cell in response to different exercise modalities

Exercise not only regulates neurotransmitters and synapse formation but also enhances the function of multiple brain regions, beyond cortical activation. Prolonged aerobic or resistance exercise modality has been widely applied to reveal the beneficial effects on the brain, but few studies have investigated the direct effects of different exercise modalities and variations in exercise intensity on the neuroinflammatory response in the brain and overall health. Therefore, in this study, we investigated changes in brain cells and the immune environment of the brain according to exercise modalities. This study was conducted to confirm whether different exercise modalities affect the location and function of dopaminergic neurons, which are responsible for regulating voluntary movement, before utilizing animal models of disease. The results showed that high-intensity interval exercise (HIE) increased the activity of A2-reactive astrocytes in the striatum (STR), which is directly involved in movement control, resulting in neuroprotective effects. Both HIE and combined exercises (CE) increased the expression of dopamine transporter (DAT) in the STR without damaging dopamine neurons in the ventral midbrain (VM). This means that exercise training can help improve and maintain exercise capacity. In conclusion, specific exercise modalities or intensity of exercise may contribute to preventing neurodegenerative diseases such as Parkinson's disease or enhancing therapeutic effects when combined with medication for patients with neurodegenerative diseases.

Effects of exercise training on the nigrostriatal glutamatergic pathway and receptor interactions in Parkinson's disease: a systematic review

Background

The excitatory imbalance of glutamatergic neurons, caused by insufficient input from dopaminergic neurons, contributes the pathogenesis of Parkinson's disease (PD). Exercise training is one of the non-pharmacological, non-invasive therapeutic approaches.

Objective

This systematic review is the first to summarize the effects of exercise training on the regulation of protein and gene expressions within the nigrostriatal glutamatergic pathway and its receptor interactions in animal models of Parkinson's disease (PD).

Methodology

The PubMed, Web of Science, and Embase electronic databases were searched, and 9 out of 96 studies that met the PRISMA guidelines were included. These studies received a CAMARADES score ranging from 4 to 6 out of 10. The included studies utilized pharmacologically induced PD models in mice or rats with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6-hydroxydopamine (6-OHDA). The majority of studies (89%) employed treadmill training, while 11% used voluntary wheel running, with training protocols consisting of 5 days per week for 4 weeks.

Results

Exercise training reduced extracellular glutamate (Glu) and increased the expression of GLT-1, GS, Gln, and mGluR2/3 while down-regulating VGULT1 in the presynaptic terminal of the glutamatergic neurons within the nigrostriatal pathway in PD animal models. It also downregulated mGluR5 and modulated the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits: GluA1 was downregulated, inhibiting long-term potentiation, while GluA2 and GluA3 were upregulated in the nigrostriatal pathway in PD animal models. In addition, the exercise training downregulated the N-methyl-D-aspartate (NMDA) receptors, Arc, Cav1.3, CaMKII, and p-CaMKII in the nigrostriatal pathway in PD animal models.

Conclusion

Exercise training exerted a neuroprotective effect on the glutamatergic pathway in Parkinson's disease (PD) animal models by limiting excess glutamate in the synaptic cleft. Exercise training modulated the ionotropic receptors and limited the glutamatergic excitatory imbalance within the nigrostriatal pathway in PD animal models. It also improved motor function, including balance, coordination, and gait parameters.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#recordDetails, identifier CRD42024564127.

Effects of exercise training on nigrostriatal neuroprotection in Parkinson's disease: a systematic review

Introduction

Parkinson's disease (PD) is characterized by progressive neurodegeneration within the nigrostriatum, leading to motor dysfunction. This systematic review aimed to summarize the effects of various exercise training regimens on protein or gene expression within the nigrostriatum and their role in neuroprotection and motor function improvement in animal models of Parkinson's disease (PD).

Methods

PubMed, EMBASE, and Web of Science were searched up to June 2024 and included sixteen studies that adhere to PRISMA guidelines and CAMARADES checklist scores ranging from 4 to 6 out of 10. Various exercise training regimens, administered 5 days per week for 6.5 weeks, were applied to MPTP, 6-OHDA, and PFF-α-synuclein-induced PD animal models.

Results

Exercise training was found to downregulate the inflammatory pathway by attenuating α-synuclein aggregation, inhibiting the TLR/MyD88/IκBα signaling cascade and NF-κB phosphorylation, and decreasing pro-inflammatory cytokines IL-1β and TNF-α while increasing anti-inflammatory cytokines IL-10 and TGF-β within the nigrostriatum. It also inhibited the ASC and NLRP3 inflammasome complex and reduced the BAX/ Bcl-2 ratio and caspase-1/3 proteins, thereby decreasing neuronal apoptosis in the nigrostriatum. Exercise training elevated the expression of Pro-BDNF, BDNF, GDNF, TrkB, and Erk1/2, providing neurotrophic support to dopaminergic neurons. Furthermore, it upregulated the dopaminergic signaling pathway by increasing the expression of TH, DAT, PSD-95, and synaptophysin in the nigrostriatum.

Discussion

The findings suggested that exercise training downregulated inflammatory and apoptotic pathways while upregulated BDNF/GDNF pathways and dopaminergic signaling within the nigrostriatum. These molecular changes contributed to neuroprotection, reduced dopaminergic neuron loss, and improved motor function in PD animal models.

Systematic review registration

CRD42024484537 https://www.crd.york.ac.uk/prospero/#recordDetails.

Understanding early maladaptive schemas in autistic and ADHD individuals: exploring the impact, changing the narrative, and schema therapy considerations

Autistic/ADHD individuals are increasingly recognised as a valid minority group, with consistent research demonstrating a higher prevalence of co-occurring mental health conditions such as PTSD, anxiety, depression, substance use, and eating disorders among other mental health challenges. Due to this, there is increasing focus on the adaptations required for Autistic and ADHD individuals of current therapeutic approaches such as Schema Therapy. Particular emphasis when creating these adaptations needs to include looking at the developmental experiences, social influences, and continued adversity faced by Autistic and ADHD individuals across the lifespan, and how the narrative around Autism and ADHD within psychotherapy in general needs to change. This paper critically examines the role of attachment, unmet needs, and adverse childhood experiences in Autistic and ADHD individuals and the subsequent impact on schema development and maintenance and mental health. This will include an overview of the current literature in this area, reconsideration of understandings of Autism and ADHD, particular therapeutic considerations and adjustments and importantly discussion around the wider societal changes that need to occur to prevent schema development and reinforcement across the lifespan.

10 weeks low intensity treadmill exercise intervention ameliorates motor deficits and sustains muscle mass via decreasing oxidative damage and increasing mitochondria function in a rat model of Parkinson's disease

AIMS

Parkinson's disease (PD) is characterized by loss of dopamine neurons in the brain, which leads to motor dysfunction; excessive inflammation induces neuronal death. This study aimed to determine the most effective exercise modality to improve motor dysfunction in PD by comparing three different exercise regimens (low-intensity treadmill, high-intensity treadmill, and swimming).

MATERIALS AND METHODS

The rat model for PD was established through stereotaxic surgery, inducing unilateral 6-OHDA (6-hydroxydopamine) lesions. The low-intensity treadmill regimen exerted better protective effects on neurological and motor functions in a rat model of unilateral 6-OHDA-induced PD compared to high-intensity treadmill and swimming. The most suitable exercise regimen and the optimal duration of daily exercise (15 or 30 min) on motor activity and oxidative stress parameters were evaluated.

KEY FINDINGS

Comparison of 15 and 30 min low-intensity treadmill regimens (10 m/min) revealed 30 min daily exercise was the optimal duration and had more favorable impacts on neurological and motor function. Furthermore, we assessed the neuroprotective effects of exercising for 15 and 30 min per day for either four or ten weeks; 30 min of daily exercise for ten weeks improved mitochondrial function, the antioxidant defense system, neurotrophic factors, and muscle mass, and thereby provided protection against dopaminergic neuron loss, and motor dysfunction in rats with 6-OHDA-induced PD.

SIGNIFICANCE

30 min of daily low-intensity treadmill exercise over 10 weeks resulted in heightened mitochondrial function in both muscle and brain tissues, therefore, yielded a neuroprotective effect against the loss of dopaminergic neurons and motor dysfunction in PD rats.

Dose-response effects of physical exercise standardized volume on peripheral biomarkers, clinical response, and brain connectivity in Parkinson's disease: a prospective, observational, cohort study

Background

Exercise has been proposed as the "Universal Prescription for Parkinson's Disease"; however, the specificity of exercise dose in terms of frequency, intensity, duration, and type to be prescribed remains to be elucidated. The 2018 US updated guidelines and WHO Guidelines on Physical Activity and Sedentary Behavior recommend older adults (> 65+ years) to achieve weekly minimal activity levels, indicating the intensity of aerobic exercise as the metabolic equivalent of task and duration as minutes/week (150-300 min/week at a moderate intensity of 3-5.9 MET- or 75-150 min/week of a vigorous intensity of ≥6 MET). Translating these recommendations to PD patients, the study aimed to assess the dose-response effects of standardized volume of structured exercise, measured as METs-minutes/week (weekly energy expenditure) of two different rehabilitation settings to quantify the change in neurotrophic factors. The exercise-induced benefits between the two rehabilitation settings will be evaluated based on motor and non-motor symptoms, kinematic parameters of gait, cognitive function, quality of life, and cortical activity and brain connectivity.

Methods

METEX-PD is a pilot, prospective, observational, cohort study. The study will enroll consecutively thirty (N = 30) participants with mild-to-moderate Parkinson's disease diagnosis to be assigned to a non-intensive or intensive rehabilitation group. The non-intensive rehabilitation group will achieve a range of 180-270 METs-min/week (90 min/week of low-intensity aerobic exercise, 2-3 METs), while the intensive rehabilitation group will exercise at 1350-1980 METs-min/week (225 min/week of high-intensity aerobic exercise, 6-8.8 METs). The METEX-PD trial will last 12 weeks, including 4 weeks of aerobic training program and two follow-ups. Assessments will be performed at baseline (T0), at the end of the exercise program (T1-end of the program), and 4- and 8 weeks after the end of the training program (FU-1 and FU-2). The primary outcome is the change from baseline in peripheral blood BDNF levels. Secondary outcomes are differences in peripheral biomarkers, functional-motor assessments, clinical-functional evaluations, and brain imaging.

Conclusion

METEX-PD trial will enable us to estimate the change in BDNF levels and other peripheral biomarkers under precise exercise-induced energy expenditure. The primary results of the METEX-PD study will allow the development of a larger multicenter randomized controlled trial to investigate the molecular pathways inducing the change in selected neurotrophic factors, such as BDNF, IGF-1, or irisin, and the downstream mechanisms of neuroplasticity in PD patients.

Intense exercise increases dopamine transporter and neuromelanin concentrations in the substantia nigra in Parkinson's disease

Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons. Exercise has been reported to slow the clinical progression of PD. We evaluated the dopaminergic system of patients with mild and early PD before and after a six-month program of intense exercise. Using 18F-FE-PE2I PET imaging, we measured dopamine transporter (DAT) availability in the striatum and substantia nigra. Using NM-MRI, we evaluated the neuromelanin content in the substantia nigra. Exercise reversed the expected decrease in DAT availability into a significant increase in both the substantia nigra and putamen. Exercise also reversed the expected decrease in neuromelanin concentration in the substantia nigra into a significant increase. These findings suggest improved functionality in the remaining dopaminergic neurons after exercise. Further research is needed to validate our findings and to pinpoint the source of any true neuromodulatory and neuroprotective effects of exercise in PD in large clinical trials.

Goal-directed and habitual control: from circuits and functions to exercise-induced neuroplasticity targets for the treatment of Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by motor and cognitive impairments. The progressive depletion of dopamine (DA) is the pathological basis of dysfunctional goal-directed and habitual control circuits in the basal ganglia. Exercise-induced neuroplasticity could delay disease progression by improving motor and cognitive performance in patients with PD. This paper reviews the research progress on the motor-cognitive basal ganglia circuit and summarizes the current hypotheses for explaining exercise intervention on rehabilitation in PD. Studies on exercise mediated mechanisms will contribute to the understanding of networks that regulate goal-directed and habitual behaviors and deficits in PD, facilitating the development of strategies for treatment of PD.

RAGE: a potential target for Epimedium's anti-neuroinflammation role in vascular dementia-insights from network pharmacology and molecular simulation

Vascular dementia (VaD), a cognitive impairment resulting from cerebrovascular issues, could be mitigated by Epimedium. This study investigates Epimedium's efficacy in VaD management through a systematic review, network pharmacology, molecular docking, and molecular dynamic simulations (MDS). Comprehensive literature searches were conducted across various databases. Epimedium's pharmacological properties were analyzed using the TCMSP database. Integration with the Aging Atlas database enabled the identification of shared targets between Epimedium and VaD. A protein-protein interaction (PPI) network was constructed, and central targets' topological attributes were analyzed using Cytoscape 3.9.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted using "ClusterProfiler" R package. The interactions between Epimedium and central targets were assessed by Molecular docking and MDS. Epimedium and its 23 bioactive components counteracted oxidative stress, neuroinflammation, and neuronal damage, thereby attenuating cognitive deterioration in VaD. A total of 78 common targets were identified, with 22 being significantly related to aging. Enrichment analysis identified 1769 GO terms and 139 KEGG pathways, highlighting the AGE-RAGE signaling pathway. Molecular docking revealed that 23 bioactive components, except Linoleyl acetate, effectively interacted with top central targets (JUN, MAPK14, IL6, FOS, TNF). MDS demonstrated that flavonoids Icariin, Kaempferol, Luteolin, and Quercetin formed stable complexes with RAGE. The study identifies RAGE as a novel therapeutic target for Epimedium in the mitigation of VaD via its anti-inflammatory properties.

Selecting the Best Animal Model of Parkinson's Disease for Your Research Purpose: Insight from in vivo PET Imaging Studies

Parkinson's disease (PD) is a debilitating neurodegenerative multisystem disorder leading to motor and non-motor symptoms in millions of individuals. Despite intense research, there is still no cure, and early disease biomarkers are lacking. Animal models of PD have been inspired by basic elements of its pathogenesis, such as dopamine dysfunction, alpha-synuclein accumulation, neuroinflammation and disruption of protein degradation, and these have been crucial for a deeper understanding of the mechanisms of pathology, the identification of biomarkers, and evaluation of novel therapies. Imaging biomarkers are non-invasive tools to assess disease progression and response to therapies; their discovery and validation have been an active field of translational research. Here, we highlight different considerations of animal models of PD that can be applied to future research, in terms of their suitability to answer different research questions. We provide the reader with important considerations of the best choice of model to use based on the disease features of each model, including issues related to different species. In addition, positron emission tomography studies conducted in PD animal models in the last 5 years are presented. With a variety of different species, interventions and genetic information, the choice of the most appropriate model to answer research questions can be daunting, especially since no single model recapitulates all aspects of this complex disorder. Appropriate animal models in conjunction with in vivo molecular imaging tools, if selected properly, can be a powerful combination for the assessment of novel therapies and developing tools for early diagnosis.

Effects and parameters of community-based exercise on motor symptoms in Parkinson's disease: a meta-analysis

BACKGROUND

Community-based exercise is a continuation and complement to inpatient rehabilitation for Parkinson's disease and does not require a professional physical therapist or equipment. The effects, parameters, and forms of each exercise are diverse, and the effect is affected by many factors. A meta-analysis was conducted to determine the effect and the best parameters for improving motor symptoms and to explore the possible factors affecting the effect of community-based exercise.  METHODS: We conducted a comprehensive search of six databases: PEDro, PubMed/Medline, CENTRAL, Scopus, Embase, and WOS. Studies that compared community-based exercise with usual care were included. The intervention mainly included dance, Chinese martial arts, Nordic walking, and home-based exercise. The primary outcome measure was the Unified Parkinson's Disease Rating Scale part III (UPDRS-III) score. The mean difference (95% CI) was used to calculate the treatment outcomes of continuous outcome variables, and the I² statistic was used to estimate the heterogeneity of the statistical analysis. We conducted subgroup analysis and meta-regression analysis to determine the optimal parameters and the most important influencing factors of the exercise effect.  RESULTS: Twenty-two studies that enrolled a total of 809 subjects were included in the analysis. Exercise had a positive effect on the UPDRS-III (MD = -5.83; 95% CI, -8.29 to -3.37), Timed Up and Go test (MD = -2.22; 95% CI -3.02 to -1.42), UPDRS ((MD = -7.80; 95% CI -10.98 to -6.42), 6-Minute Walk Test (MD = 68.81; 95% CI, 32.14 to 105.48), and Berg Balance Scale (MD = 4.52; 95% CI, 2.72 to 5.78) scores. However, the heterogeneity of each included study was obvious. Weekly frequency, age, and duration of treatment were all factors that potentially influenced the effect.

CONCLUSIONS

This meta-analysis suggests that community-based exercise may benefit motor function in patients with PD. The most commonly used modalities of exercise were tango and tai chi, and the most common prescription was 60 min twice a week. Future studies should consider the influence of age, duration of treatment, and weekly frequency on the effect of exercise.

PROSPERO TRIAL REGISTRATION NUMBER

CRD42022327162.

HIF-1 signalling pathway was identified as a potential new pathway for Icariin's treatment against Alzheimer's disease based on preclinical evidence and bioinformatics

Aim: Alzheimer's disease (AD) is a neurodegenerative condition that is characterized by the gradual loss of memory and cognitive function. Icariin, which is a natural chemical isolated from Epimedii herba, has been shown to protect against AD. This research examined the potential mechanisms of Icariin's treatment against AD via a comprehensive review of relevant preclinical studies coupled with network pharmacology. Methods: The PubMed, Web of Science, CNKI, WANFANG, and VIP databases were used to identify the relevant studies. The pharmacological characteristics of Icariin were determined using the SwissADME and TCMSP databases. The overlapping targets of Icariin and AD were then utilized to conduct disease oncology (DO) analysis to identify possible hub targets of Icariin in the treatment of AD. The hub targets were then used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and the interactions of the targets and Icariin were assessed via molecular docking and molecular dynamics simulation (MDS). Results: According to the literature review, Icariin alleviates cognitive impairment by regulating the expression of Aβ1-42, Aβ1-40, BACE1, tau, hyperphosphorylated tau, and inflammatory mediators. DO analysis revealed 35 AD-related hub targets, and the HIF-1 signalling pathway was ranked first according to the KEGG pathway analysis. Icariin effectively docked with the 35 hub targets and HIF-1α, and the dynamic binding of the HIF-1-Icariin complex within 100 ns indicated that Icariin contributed to the stability of HIF-1α. Conclusion: In conclusion, our research used a literature review and network pharmacology methods to identify the HIF-1 signalling pathway as a potential pathway for Icariin's treatment against AD.

Targeting Macroautophagy as a Therapeutic Opportunity to Treat Parkinson's Disease

Macroautophagy, an evolutionary conserved catabolic process in the eukaryotic cell, regulates cellular homeostasis and plays a decisive role in self-engulfing proteins, protein aggregates, dysfunctional or damaged organelles, and invading pathogens. Growing evidence from in vivo and in vitro models shows that autophagy dysfunction plays decisive role in the pathogenesis of various neurodegenerative diseases, including Parkinson's disease (PD). PD is an incurable and second most common neurodegenerative disease characterised by neurological and motor dysfunction accompanied of non-motor symptoms that can also reduce the life quality of patients. Despite the investment in research, the aetiology of the disease is still unknown and the therapies available are aimed mostly at ameliorating motor symptoms. Hence, therapeutics regulating the autophagy pathway might play an important role controlling the disease progression, reducing neuronal loss and even ameliorating non-motor symptoms. In this review, we highlight potential therapeutic opportunities involved in different targeting options like an initiation of autophagy, Leucine-rich repeat kinase 2 (LRRK2) inhibition, mitophagy, lysosomes, lipid metabolism, immune system, gene expression, biomarkers, and also non-pharmacological interventions. Thus, strategies to identify therapeutics targeting the pathways modulating autophagy might hold a future for therapy development against PD.

The impact of aerobic and resistance training intensity on markers of neuroplasticity in health and disease

OBJECTIVE

To determine the effects of low- vs. high-intensity aerobic and resistance training on motor and cognitive function, brain activation, brain structure, and neurochemical markers of neuroplasticity and the association thereof in healthy young and older adults and in patients with multiple sclerosis, Parkinson's disease, and stroke.

DESIGN

Systematic review and robust variance estimation meta-analysis with meta-regression.

DATA SOURCES

Systematic search of MEDLINE, Web of Science, and CINAHL databases.

RESULTS

Fifty studies with 60 intervention arms and 2283 in-analyses participants were included. Due to the low number of studies, the three patient groups were combined and analyzed as a single group. Overall, low- (g=0.19, p = 0.024) and high-intensity exercise (g=0.40, p = 0.001) improved neuroplasticity. Exercise intensity scaled with neuroplasticity only in healthy young adults but not in healthy older adults or patient groups. Exercise-induced improvements in neuroplasticity were associated with changes in motor but not cognitive outcomes.

CONCLUSION

Exercise intensity is an important variable to dose and individualize the exercise stimulus for healthy young individuals but not necessarily for healthy older adults and neurological patients. This conclusion warrants caution because studies are needed that directly compare the effects of low- vs. high-intensity exercise on neuroplasticity to determine if such changes are mechanistically and incrementally linked to improved cognition and motor function.