Neuropsychological and clinical heterogeneity of cognitive impairment and dementia in patients with Parkinson's disease

Spatiotemporal Progression Patterns of Dopamine Availability and Deep Gray Matter Volume in Parkinson Disease-Related Cognitive Impairment

BACKGROUND AND OBJECTIVES

Cognitive impairment is a frequent nonmotor symptom in patients with Parkinson disease (PD), and early cognitive decline is often attributed to dopaminergic system dysfunction. We aimed to explore spatiotemporal progression patterns of striatal dopamine availability and regional brain volume based on cognitive status among patients with PD.

METHODS

This retrospective, cross-sectional study included patients with newly diagnosed PD who were not taking medication for this condition who visited a university-affiliated hospital in Seoul between January 2018 and December 2020. Patients were classified as having normal cognition (PD-NC), mild cognitive impairment (PD-MCI), or PD dementia (PDD) based on Seoul Neuropsychological Screening Battery-II, which includes 31 subsets covering activities of daily living and 5 cognitive domains. They all had brain imaging with MRI and PET with 18F-N-(3-fluoropropyl)-2beta-carbon ethoxy-3beta-(4-iodophenyl) nortropane at baseline. Subsequently, standardized uptake value ratios (SUVRs) for regional dopamine availability and regional gray matter volumes were obtained using automated segmentation. These metrics were compared across cognitive status groups, and spatiotemporal progression patterns were analyzed using the Subtype and Stage Inference machine learning technique.

RESULTS

Among 168 patients (mean age, 73.3 ± 6.1 years; 81 [48.2%] women), 65 had PD-NC, 65 had PD-MCI, and 38 had PDD. Patients with PD-MCI exhibited lower SUVRs (3.61 ± 1.31, p < 0.001) in the caudate than patients with PD-NC (4.43 ± 1.21) but higher SUVRs than patients with PDD (2.39 ± 1.06). Patients with PD-NC had higher thalamic SUVRs (1.55 ± 0.16, p < 0.001) than patients with both PD-MCI (1.45 ± 0.16) and PDD (1.38 ± 0.19). Regional deep gray matter volumes of the caudate (p = 0.015), putamen (p = 0.012), globus pallidus (p < 0.001), thalamus (p < 0.001), hippocampus (p < 0.001), and amygdala (p < 0.001) were more reduced in patients with PD-MCI or PDD than in patients with PD-NC, and the SUVR of the caudate correlated with caudate volume (r = 0.187, p = 0.015). Hippocampal atrophy was the initial change influencing cognitive impairment. The reduced dopamine availability of the thalamus preceded reductions in volume across most deep gray matter regions.

DISCUSSION

Our finding underscores the association between decreased dopamine availability and volume of the caudate and thalamus with cognitive dysfunction in PD. The dopamine availability of the caudate and thalamus was reduced before the volume of the caudate and thalamus was decreased, highlighting the spatiotemporal association between dopaminergic and structural pathology in cognitive impairment in PD.

Let Us Talk Money: Subjectively Reported Financial Performance of People Living with Neurodegenerative Diseases-A Systematic Review

Neurodegenerative diseases (NDDs) form a heterogeneous, widespread group of disorders, generally characterized by progressive cognitive decline and neuropsychiatric disturbances. One of the abilities that seems particularly vulnerable to the impairments in neurodegenerative diseases is the capability to manage one's personal finances. Indeed, people living with neurodegenerative diseases were shown to consistently present with more problems on performance-based financial tasks than healthy individuals. While objective, performance-based tasks provide insight into the financial competence of people living with neurodegenerative diseases in a controlled, standardized setting; relatively little can be said, based on these tasks, about their degree of success in dealing with the financial demands, issues, or questions of everyday life (i.e., financial performance). The aim of this systematic review is to provide an overview of the literature examining self and informant reports of financial performance in people living with neurodegenerative diseases. In total, 22 studies were included that compared the financial performance of people living with mild cognitive impairment (MCI), Alzheimer's disease (AD), Parkinson's disease, or multiple sclerosis to a (cognitively) normal control group. Overall, the results indicate that people living with neurodegenerative diseases are more vulnerable to impairments in financial performance than cognitively normal individuals and that the degree of reported problems seems to be related to the severity of cognitive decline. As the majority of studies however focused on MCI or AD and made use of limited assessment methods, future research should aim to develop and adopt more comprehensive assessments to study strengths and weaknesses in financial performance of people living with different neurodegenerative diseases.

The effect of anticholinergic drugs on cognition of patients with Parkinson's disease: a cohort study from the Egyptian population

BACKGROUND

Cognitive dysfunction is a non-motor manifestation of Parkinson's disease (PD). We aimed to determine the frequency and patterns of cognitive dysfunction in treated patients with PD and their predictors.

RESEARCH DESIGN AND METHODS

This study included 80 patients (male = 48; female = 32) and 30 healthy individuals. They underwent neuropsychiatric evaluations. Measurements included Beck's depression inventory - II (BDI-II), mini-mental state examination (MMSE) and Montreal cognitive assessment (MoCA).

RESULTS

Patients had mean age of 55.56 ± 9.06 yrs, duration of PD of 4.86 ± 2.71 yrs and Hoehn and Yahr Scoring of 2.19 ± 0.89. They were on levodopa/carbidopa therapy and adjuvant therapy with benztropine mesylate, an anticholinergic drug, (n = 51) or amantadine sulfate, a dopaminergic drug, (n = 29). Sixteen (20%) had moderate depressive symptoms. Mild and moderate cognitive impairments were reported in 38.8% and 28.8% (by MMSE) and 46.3% and 31.3% (by MoCA). Patients had lower global cognitive scoring (p = 0.0001) and scorings of different cognitive functions (naming, attention, language, abstraction, memory and orientation) than controls. Patients treated with benztropine had lower cognition than with amantadine. Correlation analyses showed that lower cognition was only associated with chronic PD and its treatment (p = 0.0001).

CONCLUSIONS

Cognitive dysfunction is common with PD (77.5%) particularly with anticholinergic drugs. De-prescription of anticholinergics is recommended for patients with PD.

Does the Montreal Cognitive Assessment (MoCA) identify cognitive impairment profiles in Parkinson's disease? An exploratory study

An important proportion of patients with Parkinson's Disease (PD) present signs of cognitive impairment, although this is heterogeneous. In an attempt to classify this, the dual syndrome hypothesis distinguishes between two profiles: one defined by attentional and executive problems with damage in anterior cerebral regions, and another with mnesic and visuospatial alterations, with damage in posterior cerebral regions. The Montreal Cognitive Assessment (MoCA) is one of the recommended screening tools, and one of the most used, to assess cognitive impairment in PD. However, its ability to specifically identify these two profiles of cognitive impairment has not been studied. The aim of this study was, therefore, to analyze the capacity of the MoCA to detect cognitive impairment, and also to identify anterior and posterior profiles defined by the dual syndrome hypothesis. For this purpose, 59 patients with idiopathic PD were studied with the MoCA and a neuropsychological battery of tests covering all cognitive domains. Results of logistic regression analysis with ROC (Receiver Operating Characteristic) curves showed that MoCA detected cognitive impairment and identified patients with a profile of anterior/attentional and executive deficit, with acceptable sensibility and specificity. However, it did not identify patients with a posterior/mnesic-visuospatial impairment. We discuss the reasons for the lack of sensitivity of MoCA in this profile, and other possible implications of these results with regards the usefulness of this tool to assess cognitive impairment in PD.

Targeting the adenosine A2A receptor for neuroprotection and cognitive improvement in traumatic brain injury and Parkinson's disease

Adenosine exerts its dual functions of homeostasis and neuromodulation in the brain by acting at mainly 2 G-protein coupled receptors, called A1 and A2A receptors. The adenosine A2A receptor (A2AR) antagonists have been clinically pursued for the last 2 decades, leading to final approval of the istradefylline, an A2AR antagonist, for the treatment of OFF-Parkinson's disease (PD) patients. The approval paves the way to develop novel therapeutic methods for A2AR antagonists to address 2 major unmet medical needs in PD and traumatic brain injury (TBI), namely neuroprotection or improving cognition. In this review, we first consider the evidence for aberrantly increased adenosine signaling in PD and TBI and the sufficiency of the increased A2AR signaling to trigger neurotoxicity and cognitive impairment. We further discuss the increasing preclinical data on the reversal of cognitive deficits in PD and TBI by A2AR antagonists through control of degenerative proteins and synaptotoxicity, and on protection against TBI and PD pathologies by A2AR antagonists through control of neuroinflammation. Moreover, we provide the supporting evidence from multiple human prospective epidemiological studies which revealed an inverse relation between the consumption of caffeine and the risk of developing PD and cognitive decline in aging population and Alzheimer's disease patients. Collectively, the convergence of clinical, epidemiological and experimental evidence supports the validity of A2AR as a new therapeutic target and facilitates the design of A2AR antagonists in clinical trials for disease-modifying and cognitive benefit in PD and TBI patients.

Cognitive function in different motor subtypes of Parkinson's disease: A systematic review protocol

Background and Aims

As the fastest-growing neurological disorder globally, a better understanding of Parkinson's disease (PD) is needed to improve patient outcomes and reduce the increasing economic and healthcare burden associated with the disease. Whilst classified as a movement disorder, this disease is highly heterogeneous, encompassing a broad range of both motor and non-motor symptoms (NMS). Cognitive impairment, presenting as either mild cognitive impairment or PD-dementia, is one of the most prevalent and disabling NMS. To better understand heterogeneity in PD, researchers have sought to identify subtypes of individuals who share similar symptom profiles. To date, this research has predominantly focused on motor subtyping, with many studies comparing these motor subtypes on non-motor outcomes, such as cognitive impairment. However, despite evidence of a motor-cognitive relationship in healthy aging, findings regarding the presence of a motor-cognitive relationship in PD are inconsistent. In our proposed systematic review, we will investigate motor subtyping studies that have evaluated the relationship between motor and cognitive function in PD. We aim to examine what is currently known about the relationship between motor and cognitive impairment in PD and evaluate the state of the field with respect to the subtyping methods and quality of cognitive assessment tools used.

Methods

Systematic literature searches will be conducted in PubMed, PsycINFO, CINAHL, Scopus, and Web of Science.

Results

Results will be synthesized using meta-analysis and, where meta-analysis is not feasible, narrative synthesis.

Conclusion

Despite the preponderance of motor subtyping research in PD, our study will be the first to systematically review evidence regarding the association between motor subtypes and cognitive impairment. Understanding the nature of the motor-cognitive relationship in PD may lead to important insights regarding shared underlying disease pathology, which would have significant implications for early diagnosis, prognosis, and treatment of cognitive impairment in PD.

Non-motor symptoms associated with progressive loss of dopaminergic neurons in a mouse model of Parkinson's disease

Parkinson's disease (PD) is characterized by three main motor symptoms: bradykinesia, rigidity and tremor. PD is also associated with diverse non-motor symptoms that may develop in parallel or precede motor dysfunctions, ranging from autonomic system dysfunctions and impaired sensory perception to cognitive deficits and depression. Here, we examine the role of the progressive loss of dopaminergic transmission in behaviors related to the non-motor symptoms of PD in a mouse model of the disease (the TIF-IADATCreERT2 strain). We found that in the period from 5 to 12 weeks after the induction of a gradual loss of dopaminergic neurons, mild motor symptoms became detectable, including changes in the distance between paws while standing as well as the swing speed and step sequence. Male mutant mice showed no apparent changes in olfactory acuity, no anhedonia-like behaviors, and normal learning in an instrumental task; however, a pronounced increase in the number of operant responses performed was noted. Similarly, female mice with progressive dopaminergic neuron degeneration showed normal learning in the probabilistic reversal learning task and no loss of sweet-taste preference, but again, a robustly higher number of choices were performed in the task. In both males and females, the higher number of instrumental responses did not affect the accuracy or the fraction of rewarded responses. Taken together, these data reveal discrete, dopamine-dependent non-motor symptoms that emerge in the early stages of dopaminergic neuron degeneration.

Neurocognitive Impairment and Social Cognition in Parkinson's Disease Patients

In addition to motor symptoms, neurocognitive impairment (NCI) affects patients with prodromal Parkinson's disease (PD). NCI in PD ranges from subjective cognitive complaints to dementia. The purpose of this review is to present the available evidence of NCI in PD and highlight the heterogeneity of NCI phenotypes as well as the range of factors that contribute to NCI onset and progression. A review of publications related to NCI in PD up to March 2023 was performed using PubMed/Medline. There is an interconnection between the neurocognitive and motor symptoms of the disease, suggesting a common underlying pathophysiology as well as an interconnection between NCI and non-motor symptoms, such as mood disorders, which may contribute to confounding NCI. Motor and non-motor symptom evaluation could be used prognostically for NCI onset and progression in combination with imaging, laboratory, and genetic data. Additionally, the implications of NCI on the social cognition of afflicted patients warrant its prompt management. The etiology of NCI onset and its progression in PD is multifactorial and its effects are equally grave as the motor effects. This review highlights the importance of the prompt identification of subjective cognitive complaints in PD patients and NCI management.

Brain white matter changes and their associations with non-motor dysfunction in orthostatic hypotension in α-synucleinopathy: A NODDI study

BACKGROUND

The specific non-motor symptoms associated with α-synucleinopathies, including orthostatic hypotension (OH), cognitive impairment, and emotional abnormalities, have been a subject of ongoing controversy over the mechanisms underlying the development of a vicious cycle among them. The distinct structural alterations in white matter (WM) in patients with α-synucleinopathies experiencing OH, alongside their association with other non-motor symptoms, remain unexplored. This study employs axial diffusivity and density imaging (NODDI) to investigate WM damage specific to α-synucleinopathies with concurrent OH, delivering fresh evidence to supplement our understanding of the pathogenic mechanisms and pathological rationales behind the occurrence of a spectrum of non-motor functional impairments in α-synucleinopathies.

METHODS

This study recruited 49 individuals diagnosed with α-synucleinopathies, stratified into an α-OH group (n = 24) and an α-NOH group (without OH, n = 25). Additionally, 17 healthy controls were included for supine and standing blood pressure data collection, as well as neuropsychological assessments. Magnetic resonance imaging (MRI) was utilized for the calculation of NODDI parameters, and tract-based spatial statistics (TBSS) were employed to explore differential clusters. The fibers covered by these clusters were defined as regions of interest (ROI) for the extraction of NODDI parameter values and the analysis of their correlation with neuropsychological scores.

RESULTS

The TBSS analysis unveiled specific cerebral regions exhibiting disparities within the α-OH group as compared to both the α-NOH group and the healthy controls. These differences were evident in clusters that indicated a decrease in the acquisition of the neurite density index (NDI), a reduction in the orientation dispersion index (ODI), and an increase in the isotropic volume fraction (FISO) (p < 0.05). The extracted values from these ROIs demonstrated significant correlations with clinically assessed differences in supine and standing blood pressure, overall cognitive scores, and anxiety-depression ratings (p < 0.05).

CONCLUSION

Patients with α-synucleinopathies experiencing OH exhibit distinctive patterns of microstructural damage in the WM as revealed by the NODDI model, and there is a correlation with the onset and progression of non-motor functional impairments.

Safety, Tolerability, and Pharmacokinetics of the Monoamine Oxidase B Inhibitor, HEC122505, and its Major Metabolite After Single- and Multiple- Ascending Dose, and Food Effect Study in Healthy Chinese Subjects

BACKGROUND AND OBJECTIVES

HEC122505 is a potent and selectively monoamine oxidase B inhibitor that is safe and well-tolerated in preclinical models of Parkinson's disease. The objectives of single ascending dose and multiple dose pharmacokinetic trials of HEC122505 oral tablets were to determine the safety and tolerability of HEC122505, and to examine the food effect on the pharmacokinetic parameters of HEC122505 and its major metabolite HEC129870.

METHODS

The phase I study (NCT04625361) consisted of three arms: single ascending dose study (5, 20, 50, 100, 200, 300 or 400 mg HEC122505 tablets or placebo), multiple ascending dose study (20, 50 or 100 mg HEC122505 tablets or placebo once daily), and food effect (100 mg HEC122505 tablets single dose after a high-fat, high-calorie meal). All subjects completed all trial arms and were analyzed as planned.

RESULTS

Pharmacokinetic analysis showed that HEC122505 rapidly absorbed with the time to peak plasma concentration (Tmax) ranged from 0.5 to 1.75 h. In addition, maximum plasma drug concentration (Cmax) and area under the plasma concentration-time curve (AUC) increased in a dose proportional manner. Food effect study showed that a high-fat, high-calorie meal had no significant effect on the pharmacokinetics of HEC122505 and its major metabolite HEC129870, suggesting that HEC122505 could be administered in both fasted and fed state in clinical trials. The subsequent multiple-dose study evaluated doses from 20 to 100 mg dose once daily for up to 8 days. HEC122505 reached steady state after approximately 5 days with a once daily dose. In these studies, all dose of HEC122505 was generally safe and well tolerated. No grade ≥ 3 drug related adverse events (AEs) occurred.

CONCLUSION

HEC122505 was generally safe and well tolerated in the single ascending dose (ranging from 5 to 400 mg) and multiple ascending dose (50 to 200 mg once daily doses) studies. All the drug related adverse events (AEs) were Grade ≤ 2. There were no deaths, no subjects discontinued the trial due to AEs, and there were no other serious AEs. The safety and pharmacokinetic profile support once daily administration of HEC122505.

Functional alterations in resting-state networks for Theory of Mind in Parkinson's disease

In Parkinson's disease (PD), impairment of Theory of Mind (ToM) has recently attracted an increasing number of neuroscientific investigations. If and how functional connectivity of the ToM network is altered in PD is still an open question. First, we explored whether ToM network connectivity shows potential PD-specific functional alterations when compared to healthy controls (HC). Second, we tested the role of the duration of PD in the evolution of functional alterations in the ToM network. Between-group connectivity alterations were computed adopting resting-state functional magnetic resonance imaging (rs-fMRI) data of four groups: PD patients with short disease duration (PD-1, n = 72); PD patients with long disease duration (PD-2, n = 22); healthy controls for PD-1 (HC-1, n = 69); healthy controls for PD-2 (HC-2, n = 22). We explored connectivity differences in the ToM network within and between its three subnetworks: Affective, Cognitive and Core. PD-1 presented a global pattern of decreased functional connectivity within the ToM network, compared to HC-1. The alterations mainly involved the Cognitive and Affective ToM subnetworks and their reciprocal connections. PD-2-those with longer disease duration-showed an increased connectivity spanning the entire ToM network, albeit less consistently in the Core ToM network, compared to both the PD-1 and the HC-2 groups. Functional connectivity within the ToM network is altered in PD. The alterations follow a graded pattern, with decreased connectivity at short disease duration, which broadens to a generalized increase with longer disease duration. The alterations involve both the Cognitive and Affective subnetworks of ToM.

Brain Dynamics Complexity as a Signature of Cognitive Decline in Parkinson's Disease

BACKGROUND

Higuchi's fractal dimension (FD) captures brain dynamics complexity and may be a promising method to analyze resting-state functional magnetic resonance imaging (fMRI) data and detect the neuronal interaction complexity underlying Parkinson's disease (PD) cognitive decline.

OBJECTIVES

The aim was to compare FD with a more established index of spontaneous neural activity, the fractional amplitude of low-frequency fluctuations (fALFF), and identify through machine learning (ML) models which method could best distinguish across PD-cognitive states, ranging from normal cognition (PD-NC), mild cognitive impairment (PD-MCI) to dementia (PDD). Finally, the aim was to explore correlations between fALFF and FD with clinical and cognitive PD features.

METHODS

Among 118 PD patients age-, sex-, and education matched with 35 healthy controls, 52 were classified with PD-NC, 46 with PD-MCI, and 20 with PDD based on an extensive cognitive and clinical evaluation. fALFF and FD metrics were computed on rs-fMRI data and used to train ML models.

RESULTS

FD outperformed fALFF metrics in differentiating between PD-cognitive states, reaching an overall accuracy of 78% (vs. 62%). PD showed increased neuronal dynamics complexity within the sensorimotor network, central executive network (CEN), and default mode network (DMN), paralleled by a reduction in spontaneous neuronal activity within the CEN and DMN, whose increased complexity was strongly linked to the presence of dementia. Further, we found that some DMN critical hubs correlated with worse cognitive performance and disease severity.

CONCLUSIONS

Our study indicates that PD-cognitive decline is characterized by an altered spontaneous neuronal activity and increased temporal complexity, involving the CEN and DMN, possibly reflecting an increased segregation of these networks. Therefore, we propose FD as a prognostic biomarker of PD-cognitive decline. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Dopamine transporter positron emission tomography in patients with Alzheimer's disease with Lewy body disease features

In 36 normal controls (NC), 37 patients with Alzheimer's disease (AD) without parkinsonism (ADP-), 31 AD with parkinsonism (ADP+), and 40 AD with dementia with Lewy bodies (ADDLB), dual-phase dopamine transporter (DAT) positron emission tomography (PET) were performed to evaluate the diagnostic performance of DAT and early-to-delayed uptake ratios (E/Ds) in the anterior caudate (AC), posterior caudate (PC), anterior putamen (AP), posterior putamen (PP), and substantia nigra (SN) to differentiate ADP+/ADDLB from NC, and their effects on parkinsonism and cognition. DAT-SN and E/D-PP showed higher accuracies to differentiate ADP+/ADDLB from NC than DAT-PP. Among AD patients, lower DAT in the putamen and PC and higher E/Ds in the striatum were associated with severe parkinsonism, while higher E/Ds in the putamen, PC, and SN were associated with executive dysfunction. Our results suggest that decreased DAT-SN and increased E/D-PP could be biomarkers differentiating ADP+/ADDLB from pure AD and controls. Meanwhile, increased E/Ds in the putamen could reflect the severity of DLB presenting with parkinsonism and executive dysfunction among AD patients.

Correlation and underlying brain mechanisms between rapid eye movement sleep behavior disorder and executive functions in Parkinson's disease: an fNIRS study

Purpose

Rapid eye movement sleep behavior disorder (RBD) affects 30%-40% of patients with Parkinson's disease (PD) and has been linked to a higher risk of cognitive impairment, especially executive dysfunction. The aim of this study was to investigate the brain activation patterns in PD patients with RBD (PD-RBD+) compared to those without RBD (PD-RBD-) and healthy controls (HCs), and to analyze the correlation between changes in cerebral cortex activity and the severity of RBD.

Methods

We recruited 50 PD patients, including 30 PD-RBD+, 20 PD-RBD-, and 20 HCs. We used functional near infrared spectroscopy during a verbal fluency task (VFT-fNIRS) and clinical neuropsychological assessment to explore the correlation between PD-RBD+ and executive function and changes in neural activity.

Results

The VFT-fNIRS analysis revealed a significant reduction in activation among PD-RBD+ patients across multiple channels when compared to both the PD-RBD- and HC groups. Specifically, PD-RBD+ patients exhibited diminished activation in the bilateral dorsolateral prefrontal cortex (DLPFC) and the right ventrolateral prefrontal cortex (VLPFC) relative to their PD-RBD- counterparts. Furthermore, compared to the HC group, PD-RBD+ patients displayed reduced activation specifically in the right DLPFC. Significantly, a noteworthy negative correlation was identified between the average change in oxygenated hemoglobin concentration (ΔHbO2) in the right DLPFC of PD-RBD+ patients and the severity of their RBD.

Conclusion

Our study offers compelling evidence that RBD exacerbates cognitive impairment in PD, manifested as executive dysfunction, primarily attributed to reduced prefrontal activation. These aberrations in brain activation may potentially correlate with the severity of RBD.

Cognitive Profiles Stratified by Education Using Montreal Cognitive Assessment in Parkinson's Disease Patients with Freezing of Gait

Purpose

Parkinson's disease (PD) patients with freezing of gait (FOG) may present with complex and heterogeneous cognitive profiles. Owing to limited access to comprehensive neuropsychological battery in ordinary clinical practice, the Montreal Cognitive Assessment (MoCA) is likely to be easily available cognitive data for comparisons among studies. This study aims to explore the cognitive profiles stratified by education using MoCA in PD patients with FOG.

Patients and Methods

PD patients with FOG (FOG+, n = 52) and without FOG (FOG-, n = 71) were included in our study. MoCA items were categorized into five subsections (attention/working memory, executive function, episodic memory, language, and visuospatial function) referring to previously published criteria. Cognitive assessments were compared based on five subsections between groups stratified by three education levels (0-6 years, 7-12 years, and >12 years). The association of cognitive measurements with FOG were analyzed using binary logistic regression models with adjustment for variables.

Results

The total scores and subscores of each subsection of MoCA were similar between two groups of each education level. Further detailed analysis showed that a composite measure labeled "Attention/working memory-Composite" (abbreviated to Attention-C), consisting of the scores of four items (target detection task, serial sevens, digit forward and backward, and sentence repetition), were lower significantly in FOG+ group compared with FOG- group in patients with education year ≤6 years. The significant association of Attention-C with FOG held true when controlling for disease duration, but not for H-Y stage, MDS-UPDRS III, HAMA, and HAMD.

Conclusion

Overall, our findings gave a hint that Attention-C derived from MoCA might be a potential factor associated with FOG in PD patients with lower education level (education year ≤ 6 years), which will need to be validated in future studies.

Parkinson's Disease and Dementia with Lewy Bodies: One and the Same

The question whether Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are expressions of the same underlying disease has been vigorously debated for decades. The recently proposed biological definitions of Lewy body disease, which do not assign any particular importance to the dopamine system over other degenerating neurotransmitter systems, has once more brought the discussion about different types of Lewy body disease to the forefront. Here, we briefly compare PDD and DLB in terms of their symptoms, imaging findings, and neuropathology, ultimately finding them to be indistinguishable. We then present a conceptual framework to demonstrate how one can view different clinical syndromes as manifestations of a shared underlying Lewy body disease. Early Parkinson's disease, isolated RBD, pure autonomic failure and other autonomic symptoms, and perhaps even psychiatric symptoms, represent diverse manifestations of the initial clinical stages of Lewy body disease. They are characterized by heterogeneous and comparatively limited neuronal dysfunction and damage. In contrast, Lewy body dementia, an encompassing term for both PDD and DLB, represents a more uniform and advanced stage of the disease. Patients in this category display extensive and severe Lewy pathology, frequently accompanied by co-existing pathologies, as well as multi-system neuronal dysfunction and degeneration. Thus, we propose that Lewy body disease should be viewed as a single encompassing disease entity. Phenotypic variance is caused by the presence of individual risk factors, disease mechanisms, and co-pathologies. Distinct subtypes of Lewy body disease can therefore be defined by subtype-specific disease mechanisms or biomarkers.

Hippocampal synaptic failure is an early event in experimental parkinsonism with subtle cognitive deficit

Learning and memory mainly rely on correct synaptic function in the hippocampus and other brain regions. In Parkinson's disease, subtle cognitive deficits may even precede motor signs early in the disease. Hence, we set out to unravel the earliest hippocampal synaptic alterations associated with human α-synuclein overexpression prior to and soon after the appearance of cognitive deficits in a parkinsonism model. We bilaterally injected adeno-associated viral vectors encoding A53T-mutated human α-synuclein into the substantia nigra of rats, and evaluated them 1, 2, 4 and 16 weeks post-inoculation by immunohistochemistry and immunofluorescence to study degeneration and distribution of α-synuclein in the midbrain and hippocampus. The object location test was used to evaluate hippocampal-dependent memory. Sequential window acquisition of all theoretical mass spectrometry-based proteomics and fluorescence analysis of single-synapse long-term potentiation were used to study alterations to protein composition and plasticity in isolated hippocampal synapses. The effect of L-DOPA and pramipexole on long-term potentiation was also tested. Human α-synuclein was found within dopaminergic and glutamatergic neurons of the ventral tegmental area, and in dopaminergic, glutamatergic and GABAergic axon terminals in the hippocampus from 1 week post-inoculation, concomitant with mild dopaminergic degeneration in the ventral tegmental area. In the hippocampus, differential expression of proteins involved in synaptic vesicle cycling, neurotransmitter release and receptor trafficking, together with impaired long-term potentiation were the first events observed (1 week post-inoculation), preceding cognitive deficits (4 weeks post-inoculation). Later on, at 16 weeks post-inoculation, there was a deregulation of proteins involved in synaptic function, particularly those involved in the regulation of membrane potential, ion balance and receptor signalling. Hippocampal long-term potentiation was impaired before and soon after the onset of cognitive deficits, at 1 and 4 weeks post-inoculation, respectively. L-DOPA recovered hippocampal long-term potentiation more efficiently at 4 weeks post-inoculation than pramipexole, which partially rescued it at both time points. Overall, we found impaired synaptic plasticity and proteome dysregulation at hippocampal terminals to be the first events that contribute to the development of cognitive deficits in experimental parkinsonism. Our results not only point to dopaminergic but also to glutamatergic and GABAergic dysfunction, highlighting the relevance of the three neurotransmitter systems in the ventral tegmental area-hippocampus interaction from the earliest stages of parkinsonism. The proteins identified in the current work may constitute potential biomarkers of early synaptic damage in the hippocampus and hence, therapies targeting these could potentially restore early synaptic malfunction and consequently, cognitive deficits in Parkinson's disease.

Effects of physical exercise interventions on cognitive function in Parkinson's disease: An updated systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To determine whether physical exercise interventions can improve cognitive function, including overall performance and specific domains, in patients with Parkinson's disease (PD) and to provide potential evidence on how cognitive benefits can be optimized by exercise prescriptions.

METHODS

Using PubMed, Web of Science, and Cochrane Library (from inception to August 2022), four independent reviewers screened the search results and extracted data from randomized controlled trials of physical exercise interventions in patients with PD with an outcome measure of cognitive function. Random-effects meta-analysis models were used to report standardized mean differences (SMDs) with 95 % confidence intervals (CIs).

RESULTS

Twenty-one randomized controlled trials including 761 patients with PD were eligible for inclusion. Physical exercise interventions led to significant improvements in global cognitive function (SMD = 0.69; 95 % CI = 0.31 to 1.06; P < 0.001). With respect to cognitive domains, the significant effect of exercise was found on executive function (SMD = 0.94; 95 % CI = 0.05 to 1.83; P = 0.039), but not on attention/working memory, language, memory, and visuospatial function. In moderator variable analyses, the effect on global cognition was observed in combined exercise programs (SMD = 0.79; 95 % CI = 0.46 to 1.12; P < 0.001), whereas there were no significant positive effects in aerobic exercise programs, strength exercise programs, and flexibility exercise programs. In addition, exercise interventions of light-to-moderate intensity with at least 60 min in duration, and of any frequency or period, were beneficial to the global cognitive function.

CONCLUSION

This updated systematic review and meta-analysis suggests that physical exercise interventions are effective in improving global cognitive function and, to a lesser extent, executive function in patients with PD. At least 60 min a day of combined exercise programs on as many days of the week as feasible may be recommended as the non-pharmacological therapeutic option to improve cognitive function.

Interactions between functional networks in Parkinson's disease mild cognitive impairment

The study of mild cognitive impairment (MCI) is critical to understand the underlying processes of cognitive decline in Parkinson's disease (PD). Functional connectivity (FC) disruptions in PD-MCI patients have been observed in several networks. However, the functional and cognitive changes associated with the disruptions observed in these networks are still unclear. Using a data-driven methodology based on independent component analysis, we examined differences in FC RSNs among PD-MCI, PD cognitively normal patients (PD-CN) and healthy controls (HC) and studied their associations with cognitive and motor variables. A significant difference was found between PD-MCI vs PD-CN and HC in a FC-trait comprising sensorimotor (SMN), dorsal attention (DAN), ventral attention (VAN) and frontoparietal (FPN) networks. This FC-trait was associated with working memory, memory and the UPDRS motor scale. SMN involvement in verbal memory recall may be related with the FC-trait correlation with memory deficits. Meanwhile, working memory impairment may be reflected in the DAN, VAN and FPN interconnectivity disruptions with the SMN. Furthermore, interactions between the SMN and the DAN, VAN and FPN network reflect the intertwined decline of motor and cognitive abilities in PD-MCI. Our findings suggest that the memory impairments observed in PD-MCI are associated with reduced FC within the SMN and between SMN and attention networks.

The effectiveness of an immersive virtual reality and telemedicine-based cognitive intervention on prospective memory in Parkinson's disease patients with mild cognitive impairment and healthy aged individuals: design and preliminary baseline results of a placebo-controlled study

Introduction

Prospective memory (PM) impairments have been extensively documented in individuals with Parkinson's disease associated with mild cognitive impairment (PD-MCI) and in those with healthy aging. Considering how PM failure decreases individuals' quality of life and functional independence in the activities of daily living, training to enhance this ability could be a prior target of intervention.

Objective

Here, we aimed to present the study protocol and preliminary results of a novel immersive virtual reality (IVR) and telemedicine-based (TM) cognitive intervention focused on executive abilities (i.e., planning, shifting, and updating) to improve PM functioning in PD-MCI patients and healthy elderly individuals.

Methods

Outcome measures, collected before, immediately after and 2 months after the intervention, included: (1) pre-post training changes in objective cognitive functioning, evaluated with tests assessing executive functions and PM; (2) pre-post training changes in subjective perception of memory functioning, psychiatric symptoms, autonomy in daily living and quality of life, evaluated using the appropriate scales; (3) usability, feasibility and users' compliance with the proposed IVR and telemedicine program. The efficacy of this intervention compared to an active control condition is currently being evaluated in a randomized, double-blind controlled trial, which will be conducted on 30 eligible PD-MCI patients and 30 older adults.

Results

Preliminary results concerning between-group comparisons of demographic and neuropsychological screening data show a good balance among the intervention groups considered in this study. The results also suggest good levels of usability, feasibility and acceptability, thus supporting the notion that our intervention can be used to promote cognitive functioning, even in people with cognitive decline.

Conclusion

Considering the relatively low costs and easy accessibility to this program, it could prove valuable in primary prevention initiatives and early cognitive rehabilitation for dementia risk reduction.

Striatal dopamine transporter uptake, parkinsonism and cognition in Alzheimer's disease

BACKGROUND AND PURPOSE

The correlates of motor parkinsonism in Alzheimer's disease (AD) remain controversial. The effects of nigrostriatal dopaminergic degeneration on parkinsonism and cognition in biomarker-validated patients with AD were evaluated.

METHODS

This study recruited 116 patients with AD who underwent dual-phase 18 F-N-(3-fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane positron emission tomography, 18 F-florbetaben positron emission tomography, 3 T brain magnetic resonance imaging, and Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological tests. The mean cortical thickness in the frontal, temporal, parietal and occipital cortices, and the dopamine transporter (DAT) uptake in the caudate, anterior/posterior putamen and substantia nigra were quantified. The relationship between DAT uptake, mean lobar cortical thickness, UPDRS motor score and cognition was investigated using general linear models (GLMs) after controlling for age, sex, education, intracranial volume, and deep and periventricular white matter hyperintensities. A path analysis was performed for the UPDRS motor score with the same covariates.

RESULTS

Path analysis and multivariable GLMs for UPDRS motor score showed that lower caudate DAT uptake was directly associated with a higher UPDRS motor score, whereas caudate DAT uptake confounded the association between mean frontal/parietal thickness and UPDRS motor score. Multivariable GLMs for cognitive scores showed that lower caudate DAT uptake was associated with visuospatial/executive dysfunction independent of mean frontal or parietal thickness.

CONCLUSIONS

Nigrostriatal dopaminergic dysfunction is associated with parkinsonism and visuospatial/executive dysfunction in patients with AD.

Targeting calcium homeostasis and impaired inter-organelle crosstalk as a potential therapeutic approach in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as tremors, rigidity, and bradykinesia. Current therapeutic strategies for PD are limited and mainly involve symptomatic relief, with no available treatment for the underlying causes of the disease. Therefore, there is a need for new therapeutic approaches that target the underlying pathophysiological mechanisms of PD. Calcium homeostasis is an essential process for maintaining proper cellular function and survival, including neuronal cells. Calcium dysregulation is also observed in various organelles, including the endoplasmic reticulum (ER), mitochondria, and lysosomes, resulting in organelle dysfunction and impaired inter-organelle communication. The ER, as the primary calcium reservoir, is responsible for folding proteins and maintaining calcium homeostasis, and its dysregulation can lead to protein misfolding and neurodegeneration. The crosstalk between ER and mitochondrial calcium signaling is disrupted in PD, leading to neuronal dysfunction and death. In addition, a lethal network of calcium cytotoxicity utilizes mitochondria, ER and lysosome to destroy neurons. This review article focused on the complex role of calcium dysregulation and its role in aggravating functioning of organelles in PD so as to provide new insight into therapeutic strategies for treating this disease. Targeting dysfunctional organelles, such as the ER and mitochondria and lysosomes and whole network of calcium dyshomeostasis can restore proper calcium homeostasis and improve neuronal function. Additionally targeting calcium dyshomeostasis that arises from miscommunication between several organelles can be targeted so that therapeutic effects of calcium are realised in whole cellular territory.

Development of a Brief Cognitive Screening Tool for Predicting Postoperative Delirium in Patients with Parkinson's Disease: A Secondary Analysis

Background

A simple, rapid, and effective cognitive screening test appropriate for fast-paced settings with limited resources and staff is essential, especially preoperatively. This study aimed to develop and validate the short versions of Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) for predicting postoperative delirium (POD) in patients with Parkinson's disease (PD) who were scheduled for surgery.

Methods

The current study was a secondary analysis of data collected from 128 inpatients scheduled for deep brain stimulation of the subthalamic nuclei (STN-DBS) lasting >60 min, at Tsinghua University Yuquan Hospital, China. Preoperative cognitive screening was performed during the preoperative visit using the MMSE and MoCA. The optimal MMSE and MoCA cut-off scores for detecting PD-MCI was 27 and 23 respectively. The POD was assessed twice a day on the first postoperative day until discharge by the confusion assessment method. The backward conditional logistic regression analysis was used to organize the reduced versions of the MMSE or MoCA. Also, the areas under the receiver operating characteristic curves (AUCs) were examined using the DeLong test.

Results

125/128 PD patients were included in the analysis, and 27 (21.6%) developed POD. The MMSE reduced version (orientation to time, attention and calculation, and comprehension) demonstrated performance similar to the original MMSE in predicting POD (z=0.820, p=0.412). The AUC of the original MoCA and the short MoCA (visuospatial and executive attention and orientation) were 0.808 and 0.826, respectively. There was no significantly difference in the AUC values between the tests (z=0.561, p=0.575).

Conclusion

Our simplified MMSE and MoCA could be efficiently used to identify patients at risk for POD. Also, short cognitive tests could be considered while predicting POD in fast-paced preoperative settings with limited resources and staff.

Delivering Optimal Care to People with Cognitive Impairment in Parkinson's Disease: A Qualitative Study of Patient, Caregiver, and Professional Perspectives

Background

Cognitive impairment is common in Parkinson's disease (PD) and associated with lower quality of life. Cognitive impairment in PD manifests differently to other dementia pathologies. Provision of optimal care requires knowledge about the support needs of this population.

Methods

Eleven people with PD and cognitive impairment (PwP), 10 family caregivers, and 27 healthcare professionals were purposively sampled from across the United Kingdom. Semistructured interviews were conducted in 2019-2021, audio-recorded, transcribed, and analysed using reflexive thematic analysis.

Results

Cognitive impairment in PD conveyed increased complexity for clinical management and healthcare interactions, the latter driven by multifactorial communication difficulties. Techniques that helped included slow, simple, and single messages, avoiding topic switching. Information and emotional support needs were often unmet, particularly for caregivers. Diagnostic pathways were inconsistent and awareness of cognitive impairment in PD was poor, both contributing to underdiagnosis. Many felt that PwP and cognitive impairment fell through service gaps, resulting from disjointed, nonspecific, and underresourced services. Personalised care was advocated through tailoring to individual needs of PwP and caregivers facilitated by flexibility, time and continuity within services, and supporting self-management.

Conclusions

This study highlights unmet need for people with this complex condition. Clinicians should adapt their approach and communication techniques for this population and provide tailored information and support to both PwP and caregivers. Services need to be more streamlined and collaborative, providing more time and flexibility. There is a need for wider awareness and deeper understanding of this condition and its differences from other types of dementia.

Diffusion tensor imaging techniques show that parkin gene S/N167 polymorphism is responsible for extensive brain white matter damage in patients with Parkinson's disease

Objective

To explore the influence of disease and genetic factors on the white matter microstructure in patients with PD. The white matter microstructural changes in the substantia nigra-striatum system were detected by diffusion tensor imaging (DTI) using the region of interest (ROI) and diffusion tensor tracer (DTT) methods.

Methods

Patients with primary Parkinson's disease (PD) without a family history of PD were selected and divided into PD-G/G and PD-G/A groups according to their parkin S/N167 polymorphism. Control groups matched for age, sex, and gene type (G/G and G/A) were also included. Three-dimensional brain volume imaging (3D-BRAVO) and DTI were performed. The microstructural changes in the substantia nigra-striatum system were evaluated by the ROI and DTT methods. The Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Hoehn-Yahr (H-Y) staging, and the third part of the Unified Parkinson's Disease Rating (UPDRS-III) scales evaluated the cognitive and motor function impairment in patients with PD. Independent samples t-test compared normally-distributed data, and the Wilcoxon rank sum test compared measurement or categorical non-normally distributed data. Multiple regression analysis was used to analyze the correlation between various DTI indicators and the MMSE, MoCA, UPDRS-III, and H-Y scores in the PD-G/G and PD-G/A groups. P < 0.05 was considered statistically significant.

Results

The white matter microstructural changes in the nigrostriatal pathway differed significantly between the PD or PD-G/A and the control group (P < 0.05)The ROI method showed that the left globus pallidus radial diffusivity (RD) value was negatively correlated with the MMSE score (r = -0.404, P = 0.040), and the left substantia nigra (LSN) fractional anisotropy (FA) value was positively correlated with the MoCA score (r = 0.405, P = 0.040) and negatively with the H-Y stage (r = -0.479, P = 0.013).The DTT method showed that the MMSE score was positively correlated with the right substantia nigra (RSN) FA value (r = 0.592, P = 0.001) and negatively with its RD value (r = -0.439, P = 0.025). The H-Y grade was negatively correlated with the number of fibers in the RSN (r = -0.406, P = 0.040). The UPDRS-Ⅲ score was positively correlated with the mean diffusivity (r = 0.420, P = 0.033) and RD (r = 0.396, P = 0.045) values of the LSN, and the AD value of the RSN (r = 0.439, P = 0.025).

Conclusion

The DTI technique detected extensive white matter fiber damage in patients with PD, primarily in those with the G/A genotype, that led to motor and cognitivesymptoms.

Effects of cholinesterase inhibition on attention and working memory in Lewy body dementias

Cholinesterase inhibitors are frequently used to treat cognitive symptoms in Lewy body dementias (Parkinson's disease dementia and dementia with Lewy bodies). However, the selectivity of their effects remains unclear. In a novel rivastigmine withdrawal design, Parkinson's disease dementia and dementia with Lewy bodies patients were tested twice: once when taking rivastigmine as usual and once when they had missed one dose. In each session, they performed a suite of tasks (sustained attention, simple short-term recall, distractor resistance and manipulating the focus of attention) that allowed us to investigate the cognitive mechanisms through which rivastigmine affects attentional control. Consistent with previous literature, rivastigmine withdrawal significantly impaired attentional efficacy (quicker response latencies without a change in accuracy). However, it had no effects on cognitive control as assessed by the ability to withhold a response (inhibitory control). Worse short-term memory performance was also observed when patients were OFF rivastigmine, but these effects were delay and load independent, likely due to impaired visual attention. In contrast to previous studies that have examined the effects of dopamine withdrawal, cognitively complex tasks requiring control over the contents of working memory (ignoring, updating or shifting the focus of attention) were not significantly impaired by rivastigmine withdrawal. Cumulatively, these data support that the conclusion that cholinesterase inhibition has relatively specific and circumscribed-rather than global-effects on attention that may also affect performance on simple short-term memory tasks, but not when cognitive control over working memory is required. The results also indicate that the withdrawal of a single dose of rivastigmine is sufficient to reveal these impairments, demonstrating that cholinergic withdrawal can be an informative clinical as well as an investigative tool.

The Enigmatic CA2: Exploring the Understudied Region of the Hippocampus and Its Involvement in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease that affects both motor and non-motor functions. Although motor impairment is a prominent clinical sign of PD, additional neurological symptoms may also occur, particularly in the preclinical and prodromal stages. Among these symptoms, social cognitive impairment is common and detrimental. This article aims to review non-motor symptoms in PD patients, focusing on social cognitive deficits. It also examines the specific characteristics of the CA2 region and its involvement in social behavior, highlighting recent advances and perspectives. Additionally, this review provides critical insights into and analysis of research conducted in rodents and humans, which may help improve the understanding of the current status of putative therapeutic strategies for social cognitive dysfunction in PD and potential avenues related to the function of the hippocampal CA2 region.

Neuronally enriched microvesicle RNAs are differentially expressed in the serums of Parkinson's patients

Background

Circulating small RNAs (smRNAs) originate from diverse tissues and organs. Previous studies investigating smRNAs as potential biomarkers for Parkinson's disease (PD) have yielded inconsistent results. We investigated whether smRNA profiles from neuronally-enriched serum exosomes and microvesicles are altered in PD patients and discriminate PD subjects from controls.

Methods

Demographic, clinical, and serum samples were obtained from 60 PD subjects and 40 age- and sex-matched controls. Exosomes and microvesicles were extracted and isolated using a validated neuronal membrane marker (CD171). Sequencing and bioinformatics analyses were used to identify differentially expressed smRNAs in PD and control samples. SmRNAs also were tested for association with clinical metrics. Logistic regression and random forest classification models evaluated the discriminative value of the smRNAs.

Results

In serum CD171 enriched exosomes and microvesicles, a panel of 29 smRNAs was expressed differentially between PD and controls (false discovery rate (FDR) < 0.05). Among the smRNAs, 23 were upregulated and 6 were downregulated in PD patients. Pathway analysis revealed links to cellular proliferation regulation and signaling. Least absolute shrinkage and selection operator adjusted for the multicollinearity of these smRNAs and association tests to clinical parameters via linear regression did not yield significant results. Univariate logistic regression models showed that four smRNAs achieved an AUC ≥ 0.74 to discriminate PD subjects from controls. The random forest model had an AUC of 0.942 for the 29 smRNA panel.

Conclusion

CD171-enriched exosomes and microvesicles contain the differential expression of smRNAs between PD and controls. Future studies are warranted to follow up on the findings and understand the scientific and clinical relevance.

The Mechanisms of the Roles of α-Synuclein, Amyloid-β, and Tau Protein in the Lewy Body Diseases: Pathogenesis, Early Detection, and Therapeutics

Lewy body diseases (LBD) are pathologically defined as the accumulation of Lewy bodies composed of an aggregation of α-synuclein (αSyn). In LBD, not only the sole aggregation of αSyn but also the co-aggregation of amyloidogenic proteins, such as amyloid-β (Aβ) and tau, has been reported. In this review, the pathophysiology of co-aggregation of αSyn, Aβ, and tau protein and the advancement in imaging and fluid biomarkers that can detect αSyn and co-occurring Aβ and/or tau pathologies are discussed. Additionally, the αSyn-targeted disease-modifying therapies in clinical trials are summarized.

Evolution of brain network dynamics in early Parkinson's disease with mild cognitive impairment

How mild cognitive impairment (MCI) is instantiated in dynamically interacting and spatially distributed functional brain networks remains an unexplored mystery in early Parkinson's disease (PD). We applied a machine-learning technology based on personalized sliding-window algorithm to track continuously time-varying and overlapping subnetworks under the functional brain networks calculated form resting state electroencephalogram data within a sample of 33 early PD patients (13 early PD patients with MCI and 20 early PD patients without MCI). We decoded a set of subnetworks that captured surprisingly dynamically varying and integrated interactions among certain brain lobes. We observed that the master expressed subnetworks were particularly transient, and flexibly switching between high and low expression during integration into a dynamic brain network. This transience was particularly salient in a subnetwork predominantly linking temporal-parietal-occipital lobes, which decreases in both expression and flexibility in early PD patients with MCI and expresses their degree of cognitive impairment. Moreover, MCI induced a regularly interrupted, slow evolution of subnetworks in functional brain network dynamics in early PD at the individual level, and the dynamic expression characteristics of subnetworks also reflected the degree of cognitive impairment in patients with early PD. Collectively, these results provide novel and deeper insights regarding MCI-induced abnormal dynamical interaction and large-scale changes in functional brain network of early PD.

Impact of the Dopamine System on Long-Term Cognitive Impairment in Parkinson Disease: An Exploratory Study

Background

Little is known about the impact of the dopamine system on development of cognitive impairment (CI) in Parkinson disease (PD).

Objectives

We used data from a multi-site, international, prospective cohort study to explore the impact of dopamine system-related biomarkers on CI in PD.

Methods

PD participants were assessed annually from disease onset out to 7 years, and CI determined by applying cut-offs to four measures: (1) Montreal Cognitive Assessment; (2) detailed neuropsychological test battery; (3) Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) cognition score; and (4) site investigator diagnosis of CI (mild cognitive impairment or dementia). The dopamine system was assessed by serial Iodine-123 Ioflupane dopamine transporter (DAT) imaging, genotyping, and levodopa equivalent daily dose (LEDD) recorded at each assessment. Multivariate longitudinal analyses, with adjustment for multiple comparisons, determined the association between dopamine system-related biomarkers and CI, including persistent impairment.

Results

Demographic and clinical variables associated with CI were higher age, male sex, lower education, non-White race, higher depression and anxiety scores and higher MDS-UPDRS motor score. For the dopamine system, lower baseline mean striatum dopamine transporter values (P range 0.003-0.005) and higher LEDD over time (P range <0.001-0.01) were significantly associated with increased risk for CI.

Conclusions

Our results provide preliminary evidence that alterations in the dopamine system predict development of clinically-relevant, cognitive impairment in Parkinson's disease. If replicated and determined to be causative, they demonstrate that the dopamine system is instrumental to cognitive health status throughout the disease course.

TRIAL REGISTRATION

Parkinson's Progression Markers Initiative is registered with ClinicalTrials.gov (NCT01141023).

Global assessment, cognitive profile, and characteristics of mild cognitive impairment in Parkinson's disease

BACKGROUND

Cognitive deficits are evident throughout the course of Parkinson's disease (PD), with 24% of patients experiencing subtle cognitive disturbances at the time of diagnosis, and with up to 80% of patients developing PD dementia (PDD) at advanced stages of the disease PD patients with mild cognitive impairment (MCI), an at-risk phenotype of PDD, present with heterogeneous clinical characteristics that complicate the management of PD.

OBJECTIVES

This study aims to examine the characteristics of PD-MCI by using the Movement Disorder Society (MDS) diagnostic criteria and evaluate the validity of global cognitive scales in identifying PD-MCI.

METHODS

Seventy-nine (79) PD patients completed neuropsychological assessments and a comprehensive cognitive battery. PD-MCI was classified according to the level 2 MDS task force criteria. Mini-Mental State Examination (sMMSE), Montreal Cognitive Assessment (MoCA) and Parkinson's Disease Cognitive Rating Scale (PDCRS) were examined against a level 2 dichotomised PD-MCI diagnosis. Characteristics of PD-MCI were evaluated using logistic regression analysis.

RESULTS

Twenty-seven patients met criteria for PD-MCI (34%). The MoCA and PDCRS demonstrated high validity to screen for PD-MCI. Impairments in multiple cognitive domains were observed in 77.8% of PD-MCI patients. There were significantly more males in the PD-MCI group compared to PD patients without MCI (p < 0.01).

CONCLUSIONS

PD patients with MCI exhibited impairments in the attention/working memory, executive function and memory domains. Heterogeneous cognitive characteristics in PD warrant further investigation into specific cognitive subtypes to advance understanding and effective evaluation of PD-MCI.

Subjective cognitive decline in patients with Parkinson's disease: an updated review

Cognitive impairment in patients with Parkinson's disease (PD) worsens the prognosis of PD and increases caregivers' burden and economic consequences. Recently, subjective cognitive decline (SCD), which refers to self-reported cognitive decline without detectable objective cognitive dysfunction, has been regarded as an at-risk state of mild cognitive impairment (MCI) and a prodromal stage for dementia in Alzheimer's disease (AD). However, studies on PD-SCD have thus far been scarce, and at present there is no consensus regarding the definition of SCD nor a gold standard as an evaluation tool. The present review aimed to look for an association between PD-SCD and objective cognitive function and found that PD with SCD occurred with brain metabolic changes, which were consistent with early aberrant pathological changes in PD. Moreover, PD patients with SCD were likely to progress to future cognitive impairment. It is necessary to establish a guideline for the definition and evaluation of SCD in PD. A larger sample size and more longitudinal investigations are needed to verify the predictive effectiveness of PD-SCD and to detect earlier subtle cognitive decline before MCI.

Cognitive heterogeneity in Parkinson's disease: A mechanistic view

Cognitive impairment occurs in most individuals with Parkinson's disease (PD), exacting a high toll on patients, their caregivers, and the healthcare system. In this review, we begin by summarizing the current clinical landscape surrounding cognition in PD. We then discuss how cognitive impairment and dementia may develop in PD based on the spread of the pathological protein alpha-synuclein (aSyn) from neurons in brainstem regions to those in the cortical regions of the brain responsible for higher cognitive functions, as first proposed in the Braak hypothesis. We appraise the Braak hypothesis from molecular (conformations of aSyn), cell biological (cell-to-cell spread of pathological aSyn), and organ-level (region-to-region spread of aSyn pathology at the whole brain level) viewpoints. Finally, we argue that individual host factors may be the most poorly understood aspect of this pathological process, accounting for substantial heterogeneity in the pattern and pace of cognitive decline in PD.

The assessment of executive functions to test the integrity of the nigrostriatal network: A pilot study

Background

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor and non-motor symptoms. The latter mainly include affective, sleep, and cognitive deficits. Non-demented PD patients often demonstrate impairments in several executive domains following neuropsychological evaluation. The current pilot study aims at assessing the discriminatory power of the Frontal Assessment Battery-15 (FAB15) in differentiating (i) non-demented PD patients and healthy controls and (ii) PD patients with more and less pronounced motor symptoms.

Methods

Thirty-nine non-demented early-stage PD patients in the “on” dopamine state (26 females, mean age = 64.51 years, SD = 6.47, mean disease duration = 5.49 years, SD = 2.28) and 39 healthy participants (24 females, mean age = 62.60 years, SD = 5.51) were included in the study. All participants completed the FAB15. Motor symptoms of PD patients were quantified via the Unified Parkinson’s Disease Rating Scale-Part III (UPDRS-Part III) and Hoehn and Yahr staging scale (H&amp;Y).

Results

The FAB15 score, adjusted according to normative data for sex, age, and education, proved to be sufficiently able to discriminate PD patients from healthy controls (AUC = 0.69 [95% CI 0.60–0.75], SE = 0.06, p = 0.04, optimal cutoff = 11.29). Conversely, the battery lacked sufficient discriminative capability to differentiate PD patients based on the severity of motor symptoms.

Conclusion

The FAB15 may be a valid tool for distinguishing PD patients from healthy controls. However, it might be less sensitive in identifying clinical phenotypes characterized by visuospatial impairments resulting from posteroparietal and/or temporal dysfunctions. In line with previous evidence, the battery demonstrated to be not expendable in the clinical practice for monitoring the severity of PD-related motor symptoms.

Rapid eye movement sleep behavior disorder is associated with decreased quality of life and stigma in people with Parkinson's disease

BACKGROUND

Individuals with Parkinson's disease (PD) may present with rapid eye movement sleep behavior disorder (RBD). We therefore investigated the association between RBD and quality of life (QOL) in people with PD.

METHODS

Individuals with PD and a Mini-Mental State Examination score ≥ 24 were divided into two groups using the RBD screening questionnaire (RBDSQ): those with an RBDSQ score ≥ 5 were assigned to the "probable RBD" (pRBD) group, and those with a score < 5 to the "non-pRBD" group. Participants were then evaluated for motor symptoms (Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III and modified Hoehn and Yahr Scale), cognitive functions (Montreal Cognitive Assessment and Frontal Assessment Battery [FAB]), anhedonia (Snaith-Hamilton Pleasure Scale), and QOL (Parkinson's Disease Questionnaire [PDQ]-39 total and subscores for mobility, activities of daily living, emotional well-being, stigma, social support, cognition, communication, and bodily discomfort). Each measure was compared between the two groups (Mann-Whitney U test/χ² test). Multiple regression analyses were performed to identify factors contributing to the total score and the subscore of the stigma domain of the PDQ-39.

RESULTS

Ninety-three individuals with PD were recruited (mean ± standard deviation age, 67.0 ± 10.6 years). The pRBD group exhibited a longer disease duration (P = 0.006), worse FAB (P = 0.015) and PDQ-39 total (P = 0.032) scores. RBDSQ scores correlated with higher scores in the PDQ-39 stigma domain (B = 2.44, P = 0.033).

CONCLUSION

RBD is associated with worse QOL and stigma in people with PD. The RBDSQ is a useful tool for the prediction of such disturbances in QOL.

Diversity in verbal fluency performance and its associations with MRI-informed brain age matrices in normal ageing and neurocognitive disorders

INTRODUCTION

Category verbal fluency test (CVFT) has been widely used to assess and monitor the cognitive capacities in epidemiological studies and clinical trials. Pronounced discrepancy in CVFT performance has been found in individuals with different cognitive statuses. This study aimed to combine the psychometric and morphometric approaches to decode the complex verbal fluency performance in senior adults with normal ageing and neurocognitive disorders.

METHODS

This study adopted a two-stage cross-sectional design involving quantitative analyses of neuropsychological and neuroimaging data. In study I, capacity- and speed-based measures of CVFT were developed to evaluate the verbal fluency performance in normal ageing seniors (n = 261), those with mild cognitive impairment (n = 204), and those with dementia (n = 23) whose age range is from 65 to 85 years. In study II, structural magnetic resonance imaging-informed gray matter volume (GMV) and brain age matrices were calculated in a subsample (n = 52) from Study I through surface-based morphometry analysis. With age and gender as covariates, Pearson's correlation analysis was used to examine the associations of CVFT measures, GMV, and brain age matrices.

RESULTS

Speed-based measures showed extensive and stronger associations with other cognitive functions than capacity-based measures. The component-specific CVFT measures showed shared and unique neural underpinnings with lateralized morphometric features. Moreover, the increased CVFT capacity was significantly correlated with younger brain age in mild neurocognitive disorder (NCD) patients.

CONCLUSION

We found that the diversity of verbal fluency performance in normal ageing and NCD patients could be explained by a combination of memory, language, and executive abilities. The component-specific measures and related lateralized morphometric correlates also highlight the underlying theoretical meaning of verbal fluency performance and its clinical utility in detecting and tracing the cognitive trajectory in individuals with accelerated ageing.

Learned Irrelevance, Perseveration, and Cognitive Aging: A Cross-Sectional Study of Cognitively Unimpaired Older Adults

The effect of natural aging on physiologic mechanisms that regulate attentional set-shifting represents an area of high interest in the study of cognitive function. In visual discrimination learning, reward contingency changes in categorization tasks impact individual performance, which is constrained by attention-shifting costs. Perseveration (PE) and learned irrelevance (LI) are viewed as two different mechanisms that shape responses to stimuli, which are predicated on the shift in stimulus form. To date, only studies examining patients with Parkinson’s disease have provided some insight into the relationship between individual age and performance in PE and LI tasks. We enrolled 60 healthy individuals (mean [SD] age, 63.0 [12.6]) without a history of dementia, a cerebrovascular incident, or a neurodegenerative disease. No association was observed between crystallized intelligence or verbal fluency scores and reaction time in both PE (r = 0.074, p = 0.603; r = −0.124, p = 0.346) and LI (r = −0.076, p = 0.562; r = −0.081, p = 0.536) task conditions, respectively. In contrast, a statistically significant linear relationship was observed between age and reaction time (RT) for PE (r = 0.259, p = 0.046) but not for LI (r = 0.226, p = 0.083). No significant linear relationship was observed for changing RTs in PE and LI (r = 0.209, p = 0.110). The present study is the first report that provides a descriptive overview of age-related differences in PE and LI in a sample of cognitively unimpaired middle- to older-aged adults.

Premorbid performances determine the deleterious effects of nigrostriatal degeneration and pramipexole on behavioural flexibility

Subtle cognitive impairment can occur early in the course of Parkinson's disease (PD) and may manifest under different forms of executive dysfunction such as impaired cognitive flexibility. The precise contribution of nigrostriatal dopaminergic neurodegeneration to these non-motor features of the disease is poorly known. Whether such cognitive impairment associated with the disease process may also predate and contribute to the development of neuropsychiatric side-effects following dopamine replacement therapy remains largely unknown. To address these issues, we investigated the respective contributions of nigrostriatal degeneration and chronic treatment with the dopamine D3-preferring agonist pramipexole on behavioral flexibility in a rat model of PD. Flexible, intermediate and inflexible rats were identified based on baseline assessment of behavioral flexibility using an operant set-shifting task. Nigrostriatal degeneration was induced by bilateral viral-mediated expression of A53T mutated human α-synuclein in the substantia nigra pars compacta and behavioral flexibility was assessed after induction of nigrostriatal degeneration, and during chronic pramipexole treatment. Nigrostriatal degeneration impaired behavioral flexibility in flexible but not in inflexible rats. Pramipexole induced a decrease of behavioral flexibility that was exacerbated in lesioned rats and in the most flexible individuals. Furthermore, the deficits induced by pramipexole in lesioned rats affected different components of the task between flexible and inflexible individuals. This study demonstrates that nigrostriatal degeneration and pramipexole unequally impair behavioral flexibility, suggesting that the susceptibility to develop non-motor impairments upon treatment initiation could primarily depend on premorbid differences in behavioral flexibility.

Effects of monotherapy with a monoamine oxidase B inhibitor on motor symptoms in Parkinson's disease are dependent on frontal function

BACKGROUND

Monotherapy with monoamine oxidase B (MAO-B) inhibitors enhances the level of endogenous dopamine in treatment for Parkinson's disease (PD) and provides some benefits. Certain neuropsychiatric functions are also regulated by central dopaminergic activity.

AIM

To investigate the relationship of the efficacy of monotherapy with MAO-B inhibitors on motor symptoms in PD with baseline cognitive function.

PATIENTS AND METHODS

Outcomes were examined for 27 consecutive drug-naïve PD patients who received initial treatment with a MAO-B inhibitor (selegiline: 11, rasagiline: 16). Selegiline was titrated to an optimal dose. The dose of rasagiline was fixed at 1 mg/day. Motor symptoms were assessed using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III before treatment and after the efficacy reached a plateau within 19 weeks after drug initiation, and the % improvement in motor symptoms was calculated. Pre-treatment cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) and Frontal Assessment Battery (FAB). Correlations of % improvement in motor symptoms and baseline cognitive assessments were examined using Spearman correlation coefficients and multiple regression analysis.

RESULTS

In all patients, the mean % improvement in motor symptoms was 46.5% (range 0-83.3%). Spearman correlation coefficients showed the % improvement in motor symptoms was correlated with FAB (r = 0.631, p < 0.001). In multiple regression analysis with patient background factors as independent variables, only FAB was associated with improvement in motor symptoms in the MAO-B group.

CONCLUSION

Better FAB scores predict a significant improvement in motor symptoms with treatment with MAO-B inhibitors, suggesting high activity of endogenous dopamine.

The Increase of Theta Power and Decrease of Alpha/Theta Ratio as a Manifestation of Cognitive Impairment in Parkinson's Disease

In this study, we aim to assess and examine cognitive functions in Parkinson's Disease patients using EEG recordings, with a central focus on characteristics associated with a cognitive decline. Based on neuropsychological evaluation using Mini-Mental State Examination, Montreal Cognitive Assessment, and Addenbrooke's Cognitive Examination-III, 98 participants were divided into three cognitive groups. All the particpants of the study underwent EEG recordings with spectral analysis. The results revealed an increase in the absolute theta power in patients with Parkinson's disease dementia (PD-D) compared to cognitively normal status (PD-CogN, p=0.00997) and a decrease in global relative beta power in PD-D compared to PD-CogN (p=0.0413). An increase in theta relative power in the left temporal region (p=0.0262), left occipital region (p=0.0109), and right occipital region (p=0.0221) were observed in PD-D compared to PD-N. The global alpha/theta ratio and global power spectral ratio significantly decreased in PD-D compared to PD-N (p = 0.001). In conclusion, the increase in relative theta power and the decrease in relative beta power are characteristic changes in EEG recordings in PD patients with cognitive impairment. Identifying these changes can be a useful biomarker and a complementary tool in the neuropsychological diagnosis of cognitive impairment in Parkinson's Disease.

Hippocampal, basal ganglia and olfactory connectivity contribute to cognitive impairments in Parkinson's disease

Cognitive impairment is increasingly recognized as a characteristic feature of Parkinson's disease (PD), yet relatively little is known about its underlying neurobiology. Previous investigations suggest that dementia in PD is associated with subcortical atrophy, but similar studies in PD with mild cognitive impairment have been mixed. Variability in cognitive phenotypes and diversity of PD symptoms suggest that a common neuropathological origin results in a multitude of impacts within the brain. These direct and indirect impacts of disease pathology can be investigated using network analysis. Functional connectivity, for instance, may be more sensitive than atrophy to decline in specific cognitive domains in the PD population. Fifty-eight participants with PD underwent a neuropsychological test battery and scanning with structural and resting state functional MRI in a comprehensive whole-brain association analysis. To investigate atrophy as a potential marker of impairment, structural gray matter atrophy was associated with cognitive scores in each cognitive domain using voxel-based morphometry. To investigate connectivity, large-scale networks were correlated with voxel time series and associated with cognitive scores using distance covariance. Structural atrophy was not associated with any cognitive domain, with the exception of visuospatial measures in primary sensory and motor cortices. In contrast, functional connectivity was associated with attention, executive function, language, learning and memory, visuospatial, and global cognition in the bilateral hippocampus, left putamen, olfactory cortex, and bilateral anterior temporal poles. These preliminary results suggest that cognitive domain-specific networks in PD are distinct from each other and could provide a network signature for different cognitive phenotypes.

Spatial Transcriptome Profiling of Mouse Hippocampal Single Cell Microzone in Parkinson's Disease

The hippocampus is an important part of the limbic system in the human brain that has essential roles in spatial navigation and cognitive functions. It is still unknown how gene expression changes in single-cell in different spatial locations of the hippocampus of Parkinson's disease. The purpose of this study was to analyze the gene expression features of single cells in different spatial locations of mouse hippocampus, and to explore the effects of gene expression regulation on learning and memory mechanisms. Here, we obtained 74 single-cell samples from different spatial locations in a mouse hippocampus through microdissection technology, and used single-cell RNA-sequencing and spatial transcriptome sequencing to visualize and quantify the single-cell transcriptome features of tissue sections. The results of differential expression analysis showed that the expression of Sv2b, Neurod6, Grp and Stk32b genes in a hippocampus single cell at different locations was significantly different, and the marker genes of CA1, CA3 and DG subregions were identified. The results of gene function enrichment analysis showed that the up-regulated differentially expressed genes Tubb2a, Eno1, Atp2b1, Plk2, Map4, Pex5l, Fibcd1 and Pdzd2 were mainly involved in neuron to neuron synapse, vesicle-mediated transport in synapse, calcium signaling pathway and neurodegenerative disease pathways, thus affecting learning and memory function. It revealed the transcriptome profile and heterogeneity of spatially located cells in the hippocampus of PD for the first time, and demonstrated that the impaired learning and memory ability of PD was affected by the synergistic effect of CA1 and CA3 subregions neuron genes. These results are crucial for understanding the pathological mechanism of the Parkinson's disease and making precise treatment plans.

Cerebral cortical thickness and cognitive decline in Parkinson's disease

In Parkinson's disease (PD), reduced cerebral cortical thickness may reflect network-based degeneration. This study performed cognitive assessment and brain MRI in 30 PD participants and 41 controls at baseline and 18 months later. We hypothesized that cerebral cortical thickness and volume, as well as change in these metrics, would differ between PD participants who remained cognitively stable and those who experienced cognitive decline. Dividing the participant sample into PD-stable, PD-decline, and control-stable groups, we compared mean cortical thickness and volume within segments that comprise the prefrontal cognitive-control, memory, dorsal spatial, and ventral object-based networks at baseline. We then compared the rate of change in cortical thickness and volume between the same groups using a vertex-wise approach. We found that the PD-decline group had lower cortical thickness within all 4 cognitive networks in comparison with controls, as well as lower cortical thickness within the prefrontal and medial temporal networks in comparison with the PD-stable group. The PD-decline group also experienced a greater rate of volume loss in the lateral temporal cortices in comparison with the control group. This study suggests that lower thickness and volume in prefrontal, medial, and lateral temporal regions may portend cognitive decline in PD.

Subjective Cognitive Complaints in Cognitively Normal Patients With Parkinson's Disease: A Systematic Review

Subjective cognitive complaints (SCCs) refer to self-perceived cognitive decline and are related to objective cognitive decline. SCCs in cognitively normal individuals are considered a preclinical sign of subsequent cognitive impairment due to Alzheimer's disease, and SCCs in cognitively normal patients with Parkinson's disease (PD) are also gaining attention. The aim of this review was to provide an overview of the current research on SCCs in cognitively normal patients with PD. A systematic search found a lack of consistency in the methodologies used to define and measure SCCs. Although the association between SCCs and objective cognitive performance in cognitively normal patients with PD is controversial, SCCs appear to be predictive of subsequent cognitive decline. These findings support the clinical value of SCCs in cognitively normal status in PD; however, further convincing evidence from biomarker studies is needed to provide a pathophysiological basis for these findings. Additionally, a consensus on the definition and assessment of SCCs is needed for further investigations.

Frontostriatal and limbic contributions to cognitive decline in Parkinson's disease

BACKGROUND AND PURPOSE

The circuitry underlying heterogenous cognitive profiles in Parkinson's disease (PD) remains unclear. The purpose of this study is to investigate whether structural changes in frontostriatal and limbic pathways contribute to different cognitive trajectories in PD.

METHODS

We obtained clinical and multimodal MRI data from 120 control and 122 PD subjects without dementia or severe motor disability. T1/T2-weighted images estimated volume, and diffusion imaging evaluated fractional anisotropy (FA) of frontostriatal (striatum and frontostriatal white matter [FSWM]) and limbic (hippocampus and fornix) structures. Montreal Cognitive Assessment (MoCA) gauged total and domain-specific (attention/executive and memory) cognitive function. Linear mixed-effects models were used to compare MRI and cognitive progression over 4.5 years between controls and PD and evaluate associations between baseline MRI and cognitive changes in PD.

RESULTS

At baseline, control and PD groups were comparable, except PD participants had smaller striatal volume (p < 0.001). Longitudinally, PD showed faster decline in hippocampal volume, FSWM FA, and fornix FA (ps < .016), but not striatal volume (p = .218). Total and domain-specific MoCA scores declined faster in PD (ps < .030). In PD, lower baseline hippocampal volume (p = .005) and fornix FA (p = .032), but not striatal volume (p = .662) or FSWM FA (p = .143), were associated with faster total MoCA decline. Baseline frontostriatal metrics of striatal volume and FSWM FA were associated with faster attention/executive decline (p < .038), whereas lower baseline hippocampal volume was associated with faster memory decline (p = .005).

CONCLUSION

In PD, frontostriatal structural metrics are associated with attention/executive tasks, whereas limbic changes correlated with faster global cognitive decline, particularly in memory tasks.

Serum glial cell line-derived neurotrophic factor (GDNF) a potential biomarker of executive function in Parkinson's disease

Objective

Evidence shows that the impairment of executive function (EF) is mainly attributed to the degeneration of frontal-striatal dopamine pathway. Glial cell line-derived neurotrophic factor (GDNF), as the strongest protective neurotrophic factor for dopaminergic neurons (DANs), may play a role in EF to some extent. This study mainly explored the correlation between serum GDNF concentration and EF performance in Parkinson's disease (PD).

Methods

This study recruited 45 healthy volunteers (health control, HC) and 105 PD patients, including 44 with mild cognitive impairment (PD-MCI), 20 with dementia (PD-D), and 20 with normal cognitive function (PD-N). Neuropsychological tests were performed to evaluate EF (working memory, inhibitory control, and cognitive flexibility), attention, language, memory, and visuospatial function. All subjects were tested for serum GDNF and homovanillic acid (HVA) levels by ELISA and LC-ESI-MS/MS, respectively.

Results

PD-MCI patients showed impairments in the trail making test (TMT) A (TMT-A), TMT-B, clock drawing test (CDT) and semantic fluency test (SFT), whereas PD-D patients performed worse in most EF tests. With the deterioration of cognitive function, the concentration of serum GDNF and HVA in PD patients decreased. In the PD group, the serum GDNF and HVA levels were negatively correlated with TMT-A (r _GDNF = -0.304, P < 0.01; r _HVA = -0.334, P < 0.01) and TMT-B (r _GDNF = -0.329, P < 0.01; r _HVA = -0.323, P < 0.01) scores. Serum GDNF levels were positively correlated with auditory verbal learning test (AVLT-H) (r = 0.252, P < 0.05) and SFT (r = 0.275, P < 0.05) scores. Serum HVA levels showed a positively correlation with digit span test (DST) (r = 0.277, P < 0.01) scores. Stepwise linear regression analysis suggested that serum GDNF and HVA concentrations and UPDRS-III were the influence factors of TMT-A and TMT-B performances in PD patients.

Conclusion

The decrease of serum GDNF concentration in PD patients was associated with impaired inhibitory control, cognitive flexibility, and attention performances. The changes of GDNF and HVA might synergistically participate in the occurrence and development of executive dysfunction in PD patients.

Neurophysiological consequences of synapse loss in progressive supranuclear palsy

Synaptic loss occurs early in many neurodegenerative diseases and contributes to cognitive impairment even in the absence of gross atrophy. Currently, for human disease there are few formal models to explain how cortical networks underlying cognition are affected by synaptic loss. We advocate that biophysical models of neurophysiology offer both a bridge from clinical to preclinical models of pathology, and quantitative assays for experimental medicine. Such biophysical models can also disclose hidden neuronal dynamics generating neurophysiological observations like electro- and magneto-encephalography. Here, we augment a biophysically informed mesoscale model of human cortical function by inclusion of synaptic density estimates as captured by [11C]UCB-J positron emission tomography, and provide insights into how regional synapse loss affects neurophysiology. We use the primary tauopathy of progressive supranuclear palsy (Richardson's syndrome) as an exemplar condition, with high clinicopathological correlations. Progressive supranuclear palsy causes a marked change in cortical neurophysiology in the presence of mild cortical atrophy and is associated with a decline in cognitive functions associated with the frontal lobe. Using parametric empirical Bayesian inversion of a conductance-based canonical microcircuit model of magnetoencephalography data, we show that the inclusion of regional synaptic density-as a subject-specific prior on laminar specific neuronal populations-markedly increases model evidence. Specifically, model comparison suggests that a reduction in synaptic density in inferior frontal cortex affects superficial and granular layer glutamatergic excitation. This predicted individual differences in behaviour, demonstrating the link between synaptic loss, neurophysiology, and cognitive deficits. The method we demonstrate is not restricted to progressive supranuclear palsy or the effects of synaptic loss: such pathology-enriched dynamic causal models can be used to assess the mechanisms of other neurological disorders, with diverse non-invasive measures of pathology, and is suitable to test the effects of experimental pharmacology.

Effects of a forced cycling program with cognitive stimulation on symptomatology, physical condition, and cognition in people diagnosed with Parkinson disease

BACKGROUND AND OBJECTIVES

Parkinson disease may present difficulties in performing dual tasks. The use of dual tasks during training can improve different abilities. Therefore, the objective of this study is creating a protocol, based on standard protocol items recommendations for interventional trials compliant, for a clinical trial study conduct, review, reporting, and interpretation. This protocol will provide the framework and a guide to a randomized double-blind study, that will be conducted to assess the influence of a cycling exercise program combined with a cognitive task, on cognitive and physical Parkinson disease aspects.

METHODS

Designed a protocol for a double-blind randomized study, where participants will perform a dual tasks intervention with cycling and a cognitive task. The revised version of the unified Parkinson disease rating scale, the Parkinson disease questionnaire, the timed up and go Test, the 30 seconds chair sit to stand test, the Stroop and the trail making test will be used to measure outcomes.

DISCUSSION

Research in Parkinson disease suggests that an improvement of motor and cognitive functions of Parkinson disease patients can be achieved by modifying different motor and cognitive pathways. The results of the present study will yield findings on both the physical and cognitive response to an intervention that combines a cognitive task with a motor task in Parkinson disease patients and will be essential tool for a better conducting of the clinical trial study.

The effect of dopaminergic neuron transplantation and melatonin co-administration on oxidative stress-induced cell death in Parkinson's disease

A gradual degeneration of the striatum and loss of nigral dopamine cells are characteristic of Parkinson's disease. Nowadays, combination therapy for neurodegenerative disease is considered. This study aimed to investigate the effects of melatonin and dopaminergic neurons derived from adipose tissue stem cells (ADSCs) in a rat model of Parkinson's disease. Parkinson's disease was induced in rats using neurotoxin 6-Hydroxydopamine. The treatment was performed using melatonin and dopaminergic neurons transplantation. Subsequently, behavioral tests, western blot analysis for Caspase-3 expression, GSH (Glutathione) content and stereology analysis for the volume and cell number of substantia nigra and striatum were performed. Treatment with melatonin and dopaminergic neuron transplantation increased the number of neurons in substantia nigra and striatum while the number of glial cell and the volume of substantia nigra and striatum did not show significant change between groups. Western blot analysis for caspase 3 indicated the significant differences between groups. The results also indicated the increased level of glutathione (GSH) content in treatment groups. this study showed that combination therapy with melatonin and dopaminergic neurons could greatly protect the neurons, reduce oxidative stress and improve the symptoms of PD.