The Sydney multicenter study of Parkinson's disease: The inevitability of dementia at 20 years

Apolipoprotein E genotypes and amyloid burden associated with cognitive decline in non-demented Parkinson's disease patients: A preliminary analysis

BACKGROUND

Cognitive impairment is a common non-motor manifestation in Parkinson's disease (PD). Amyloidosis seems to accelerate the onset of dementia in PD. The Apolipoprotein (APOE) ε4 genotype is linked to amyloid aggregation and has been suggested to be a candidate for development of PD dementia, while other APOE alleles have been less investigated.

METHODS

Forty-eight non-demented PD patients were included (ε2/ε3 carriers: n = 8; ε3/ε3 carriers: n = 35; and ε3/ε4 carriers: n = 5). Patients underwent APOE genotyping, a neuropsychological exam and a [18F]-Flutemetamol PET. Statistical Parametric Mapping 12 was used to analyze regional amyloid differences by APOE genotypes. Cognitive assessment was re-administered after follow-up.

RESULTS

APOE ε3/ε4 carriers showed significant amyloid load in left middle occipital areas in comparison with APOE ε3/ε3, whereas APOE ε3/ε4 exhibited several areas of amyloid accumulation in comparison with APOE ε2/ε3 that disappeared after family-wise error cluster level correction, but which hold in nonparametric analyses. No amyloid load differences were found between APOE ε2/ε3 and APOE ε3/ε3. The frequency of progression of cognitive decline was 80 % in ε3/ε4, 50 % in ε2/ε3, and 22.86 % in ε3/ε3 carriers.

CONCLUSIONS

This compared regional amyloid deposition and cognitive evolution among APOE genotypes. Our preliminary findings suggest an association between APOE ε4 and amyloid burden in posterior cortical areas in non-demented PD and a tendency to a higher frequency of cognitive decline. Larger studies should explore cognition and amyloid burden in APOE ε2 carriers.

Lasting Impact: Exploring the Brain Mechanisms that Link Traumatic Brain Injury to Parkinson's Disease

Development of Parkinson's Disease (PD) is linked with a history of traumatic brain injury (TBI), although the mechanisms driving this remain unclear. Of note, many key parallels have been identified between the pathologies of PD and TBI; in particular, PD is characterised by loss of dopaminergic neurons from the substantia nigra (SN), accompanied by broader changes to dopaminergic signalling, disruption of the Locus Coeruleus (LC) and noradrenergic system, and accumulation of aggregated α-synuclein in Lewy Bodies, which spreads in a stereotypical pattern throughout the brain. Widespread disruptions to the dopaminergic and noradrenergic systems, including progressive neuronal loss from the SN and LC, have been observed acutely following injury, some of which have also been identified chronically in TBI patients and preclinical models. Furthermore, changes to α-synuclein expression are also seen both acutely and chronically following injury throughout the brain, although detailed characterisation of these changes and spread of pathology is limited. In this review, we detail the current literature regarding dopaminergic and noradrenergic disruption and α-synuclein pathology following injury, with particular focus on how these changes may predispose individuals to prolonged pathology and progressive neurodegeneration, particularly the development of PD. While it is increasingly clear that TBI is a key risk factor for the development of PD, significant gaps remain in current understanding of neurodegenerative pathology following TBI, particularly chronic manifestations of injury.

Approaches for treating neuropsychiatric symptoms in Parkinson's disease: a narrative review

Neuropsychiatric symptoms in Parkinson's disease (PD) are highly prevalent and profoundly disabling, often emerging even before the onset of motor symptoms. As the disease progresses, these symptoms usually become increasingly impairing and are now recognized as having the greatest impact on quality of life not only for patients but also for caregivers. In recent years, there have been significant advances in the diagnosis and management of neuropsychiatric symptoms. However, there are still substantial gaps in therapeutic approaches and algorithms, with limited pharmacological and nonpharmacological treatment options currently available. One of the main reasons for this is the complex molecular and neural bases of these symptoms, which involve both dopaminergic and nondopaminergic neurotransmission systems and extend far beyond the nigrostriatal pathway. As a result, the drugs currently recommended for treating neuropsychiatric symptoms in PD are few and supported by limited evidence. In this context, the experience of the treating neurologist remains critical in selecting the most appropriate individualized therapy. The aim of this paper is to review the available therapeutic options and provide an overview of current research efforts, particularly those focusing on pharmacological treatments.

Grey matter loss across deteriorating cognitive stages in Parkinson's disease

The purpose of the present study was to depict the pattern of grey matter (GM) abnormalities in patients with Parkinson's disease (PD) and various stages of cognitive decline. GM changes were investigated with the use of voxel-based morphometry in three age-matched groups consisted of PD patients with normal cognition (PD-NC, n = 20), mild cognitive impairment (PD-MCI, n = 20) and dementia (PDD, n = 21). The Parkinson's disease-cognitive rating scale (PD-CRS) was used for the neuropsychological assessment of the subjects and to define patient groups. GM atrophy was observed in the PD-MCI group in right middle and inferior temporal gyri and in the PDD group in right thalamus and hippocampus both compared to PD-NC group. Regression analyses retrieved significant associations among total, cortical, and subcortical PD-CRS scores and GM volume in multiple areas, with an exceptionally stable finding being the correlation of striatal atrophy with deteriorating cognitive function. Significant associations were also observed between GM volume in specific regions and the performance of patients in particular PD-CRS items. The study findings reveal a central role of striatal atrophy in the PD-related cognitive decline. Degenerative changes in temporal regions could contribute to MCI, while hippocampal and thalamic atrophy are proposed to accompany the transition to dementia.

The gut-brain axis in early Parkinson's disease: from prodrome to prevention

Parkinson's disease is the second most common neurodegenerative disorder and fastest growing neurological condition worldwide, yet its etiology and progression remain poorly understood. This disorder is characterized pathologically by the prion-like spread of misfolded neuronal alpha-synuclein proteins in specific brain regions leading to Lewy body formation, neurodegeneration, and progressive neurological impairment. It is unclear what triggers Parkinson's and where α-synuclein protein aggregation begins, although proposed induction sites include the olfactory bulb and dorsal motor nucleus of the vagus nerve. Within the last 20 years, there has been increasing evidence that Parkinson's could be triggered by early microbiome changes and α-synuclein accumulation in the gastrointestinal system. Gut microbiota dysbiosis that alters gastrointestinal motility, permeability, and inflammation could enable prion-like spread of α-synuclein from the gut-to-brain via the enteric nervous system. Individuals with isolated rapid eye movement sleep behavior disorder have a high likelihood of developing Parkinson's and might represent a prodromal 'gut-first' subtype of the condition. The gut-first model of Parkinson's offers novel gut-based therapeutic avenues, such as anti-, pre-, and pro-biotic preparations and fecal microbiota transplants. Crucially, gut-based interventions offer an avenue to treat Parkinson's at early prodromal stages with the aim of mitigating evolution to clinically recognizable Parkinson's disease characterized by motor impairment.

Dementia with Lewy bodies and Parkinson disease dementia - the same or different and is it important?

Biological definitions of neurological diseases are now becoming a reality, although still in the research phase. This development will recategorize neurological diseases, providing objective diagnostics and the promise of therapeutics that target biological mechanisms - similar to the strategy that has proven successful in tumours and other conditions. In this Perspective article, we discuss this development for dementias with dominant Lewy pathology, as the availability of biological assays for this pathology has sparked new interest in a single disease diagnosis for all individuals positive for α-synuclein. On the basis of current evidence, we argue that an α-synuclein assay alone is unlikely to be a specific criterion for a spectrum of clinical syndromes with Lewy pathology or a definitive diagnostic marker for Lewy body dementia. We advocate that one biological assay will not reflect the complex spatiotemporal features of brain pathology. Diverse sequential mechanisms underpin the highly heterogeneous phenotypes and clinicopathological processes of Lewy body dementias. Disease modification, if possible, will be most effective when it targets the early underlying mechanisms, especially those leading to aggressive phenotypes.

Neuroimaging in advanced Parkinson's disease: insights into pathophysiology, biomarkers, and personalized therapies

Advanced Parkinson's disease (APD) represents a late stage of Parkinson's disease and is characterized by complex motor and non-motor symptoms that are less responsive to oral dopaminergic therapies. While APD has a relevant impact on patients' quality of life and requires intensified treatment, consistent diagnostic criteria have only recently been proposed. The precise pathophysiology underlying the symptoms of APD remains poorly understood, making early prognostication and intervention difficult. Neuroimaging has emerged as a promising tool for elucidating the mechanisms driving APD, identifying biomarkers for disease staging, and predicting therapeutic response. Techniques such as molecular imaging and magnetic resonance imaging provide insight into molecular and structural changes associated with the progression of PD, including protein aggregation, neuroinflammation, and regional neurodegeneration. While positron emission tomography imaging of alpha-synuclein and other pathologies offers avenues for staging and differential diagnosis, advanced magnetic resonance imaging approaches have the potential for capturing subtle microstructural changes i.e. through neuromelanin-sensitive or diffusion-weighted imaging. However, the majority of imaging studies has focused on early Parkinson's disease, leaving their applicability to APD uncertain. Future research should prioritize the validation of neuroimaging findings in well-defined APD cohorts and extend their use to predict clinical milestones such as motor fluctuations, dyskinesia, and cognitive decline. These efforts are essential to advance personalized therapeutic strategies and bridge the gap between research and clinical management of APD.

Diagnosis, evaluation & management of cognitive disorders in Parkinson's disease: A systematic review

BACKGROUND

There is considerable variability in the diagnosis, evaluation and management of cognitive disorders in Parkinson's disease (PD) across clinical services. A review of guidelines and relevant literature will provide recommendations to guide clinical decision-making. The present review aimed to summarise and critically appraise current recommendations for the diagnosis, evaluation and management of cognitive disorders in PD.

METHOD

Five academic databases (PubMed, SCOPUS, Medline, PsycINFO, CINAHL) and five grey literature databases were systematically searched in August 2024 by two independent reviewers following PRISMA guidelines. Guidelines and systematic reviews from 2003-2024 available in English and reporting at least one relevant recommendation for the diagnosis, evaluation or management of cognitive disorders in PD were included. Quality assessment was completed using the AGREE-II tool for guidelines and AMSTAR tool for systematic reviews.

RESULTS

In total, 32 guidelines and 24 systematic reviews were included. Guideline quality ranged from moderate to high and systematic review quality from critically low to high. Articles provided recommendations for cognitive impairment in PD in terms of diagnosis, neuropsychological evaluation, treatment and care. However, recommendations for cognitive tools, care considerations, and non-pharmacological interventions were limited, despite relevant evidence from the systematic review literature.

CONCLUSION

Significant gaps identified in processes for neuropsychological evaluations, inconsistent recommendations for non-pharmacological interventions, and limited care considerations calls for future iterations of the clinical practice guidelines for cognitive impairment in PD.

Data-driven characterization of distinct cognitive subtypes in Parkinson's disease dementia

Individual cognitive profiles of patients with Parkinson's disease dementia (PDD) are highly heterogeneous, suggesting possible biological subtypes. We studied 75 PD patients who developed dementia in the course of the Parkinson's Progression Markers Initiative study to investigate data-driven evidence for the existence of distinct cognitive subtypes of PDD. Using Ward's hierarchical clustering on neuropsychological test data, we identified two distinct cognitive subtypes. Despite similar dementia severity (MoCA: 20.6 vs 20.0), cluster-A exhibited more pronounced memory deficits (n = 50), whereas cluster-B showed greater visuospatial impairments (n = 25). The subtypes did not differ in demographic, motor, or MRI-based neurodegeneration measures. However, the visuospatial-predominant cluster-B had a higher prevalence of GBA mutations (p = 0.003) and hallucinations (p = 0.009). No differences were found in APOE-ε4 prevalence or cerebrospinal fluid biomarkers of Alzheimer's pathology. These findings reveal distinct memory-predominant and visuospatial-predominant PDD subtypes, which associate with different clinical and genetic features but are independent of comorbid Alzheimer's pathology.

Identifying Immune Response Protein Biomarkers in Parkinson's-Related Cognitive Impairment and Depression

A distinct immune microenvironment may develop in patients with Parkinson's disease (PD), influenced by the severity of cognitive impairment and the presence of depression. We aimed to identify blood-based immune response markers in patients with PD using a proximity extension assay (PEA). Peripheral plasma samples from 58 patients with PD and 30 healthy controls (HCs) were analyzed for 92 immune response-associated proteins using Olink's PEA technology. A panel of four proteins (SIT1, CLEC4C, EIF5A, and NFATC3) was identified, effectively differentiating patients with PD from HCs, with a combined area under the receiver operating characteristic (ROC) curve of 0.863. Among these, ITGA11 and EIF5A were particularly associated with the degree of cognitive impairment. After applying Bonferroni correction, five proteins-PPP1R9B, MILR1, BTN3A2, IRAK1, and TANK-demonstrated potentially significant differences between depressed and non-depressed patients with PD-cognitively normal (PD-CN). In the correlation analyses, PPP1R9B exhibited a positive correlation with the Hamilton Depression Rating Scale (HAMD) score (r = 0.509, P = 0.019). Furthermore, after adjusting for potential confounding factors in binary logistic regression analysis, PPP1R9B remained significantly associated with depression (P = 0.042). We identified potential blood-based immune response markers associated with the severity of cognitive impairment and depression in patients with PD. These findings provide preliminary insights into the immune-related pathology underlying non-motor symptoms of PD, potentially guiding future studies aimed at targeted therapeutic strategies. Further validation in larger, independent cohorts is warranted to confirm these associations and their clinical utility.

Mental Wellbeing and its Determinants in People with Parkinson's Disease in Ethiopia: A Mixed-Method Study

Globally, the prevalence of Parkinson's disease (PD) is increasing at an unprecedented rate. Therefore, it is imperative to provide evidence on the mental well-being of individuals with PD and identify context-specific determinants in sub-Saharan Africa to inform future interventions. An explanatory sequential mixed-methods design was employed, recruiting 304 individuals with PD who were receiving follow-up treatment. The prevalence of poor mental well-being among participants was 72.5%. Psychiatric manifestations included depression with suicidal ideation, anxiety, poor sleep quality, cognitive impairment, psychotic symptoms, and emotional and behavioral changes. Stigma was significantly associated with poor mental well-being, with an adjusted odds ratio of 1.13 (95% CI: 1.07-1.203, P < 0.001). A framework illustrating the vicious cycle of PD-related stigma, discrimination, and its impact on mental well-being was developed. Routine screening and treatment of mental disorders, along with community awareness campaigns to reduce stigma, are strongly recommended.Plain language summaryParkinson's disease (PD) exerts a significant impact on mental well-being due to its disease process and associated social and economic consequences. Therefore, assessing the prevalence of poor mental well-being, identifying manifestations of mental illness, and examining context-specific determinants in sub-Saharan Africa are essential to informing current practices and future research. Findings from this study reveal that nearly three-fourths of individuals with PD experience poor mental well-being in Ethiopia. Additionally, they exhibit a range of psychiatric manifestations, including severe conditions such as hopelessness and suicidal ideation. PD-related stigma is an independent determinant of mental well-being. People with PD face significant stigma and discrimination, largely driven by societal misconceptions about the causes of the disease. Routine screening and treatment of mental disorders, alongside the integration of mental health care into routine PD management, are essential to addressing the mental health needs of individuals with PD. Community awareness initiatives on the causes of PD are critically needed to reduce stigma and promote mental well-being. Given the high burden of mental disorders and the impact of stigma and discrimination, mental health and psychosocial interventions should prioritize individuals with PD.

Neuropsychological Tests of Memory, Visuospatial, and Language Function in Parkinson's Disease: Review, Critique, and Recommendations

BACKGROUND

Cognitive impairment in Parkinson's disease (PD) is a key non-motor complication during the disease course.

OBJECTIVES

A review of detailed cognitive instruments to detect mild cognitive impairment (PD-MCI) or dementia (PDD) is needed to establish optimal tests that facilitate diagnostic accuracy.

METHODS

We performed a systematic literature review of tests that assess memory, language including premorbid intelligence, and visuospatial domains (for tests of attention and executive functions see accompanying review) to determine suitability to assess cognition in PD. Based on in-depth scrutiny of psychometric and other relevant clinimetric properties, tests were rated as "recommended," "recommended with caveats," "suggested," or "listed" by the International Parkinson and Movement Disorder Society (IPMDS) panel of experts according to the IPMDS Clinical Outcome Assessment Scientific Evaluation Committee guidelines.

RESULTS

We included 39 tests encompassing 48 outcome measures. Seven tests (different versions or subtests of the test counted once) were recommended, including four for memory, one for visuospatial domains, one for language (including three measures), and one for estimated premorbid intelligence. Furthermore, 10 tests (12 measures) were "recommended with caveats," 11 were "suggested," and 11 (15 measures) were "listed."

CONCLUSIONS

Recommended neuropsychological tests in memory, visuospatial functions, and language are proposed to guide the assessment of cognitive impairment and its progression in PD-MCI and PDD, and for use in clinical trials to stratify participants or as outcome measures. Novel measures being developed will need extensive validation research to be "recommended." © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Non-motor Symptoms and Treatments in Parkinson's Disease

SYNOPSIS

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor and non-motor symptoms. The non-motor features may precede the onset of motor symptoms and occur throughout all stages of PD. The non-motor symptoms reflect multisystem involvement of the central and peripheral nervous systems, multiple neurotransmitters, and multiple pathologies. PD management necessitates a comprehensive approach to address non-motor symptoms, including pharmacologic and non-pharmacological interventions and often multiple different disciplines or specialists in the PD care team. This review article discusses symptoms and treatments for the non-motor symptoms of PD including those affecting mood, cognition, behavior, sleep, autonomic function, and sensory systems.

Imaging biomarkers of cortical neurodegeneration underlying cognitive impairment in Parkinson's disease

PURPOSE

Imaging biomarkers bear great promise for improving the diagnosis and prognosis of cognitive impairment in Parkinson's disease (PD). We compared the ability of three commonly used neuroimaging modalities to detect cortical changes in PD patients with mild cognitive impairment (PD-MCI) and dementia (PDD).

METHODS

53 cognitively normal PD patients (PD-CN), 32 PD-MCI, and 35 PDD underwent concurrent structural MRI (sMRI), diffusion-weighted MRI (dMRI), and [18F]FDG PET. We extracted grey matter volumes (sMRI), mean diffusivity (MD, dMRI), and standardized uptake value ratios ([18F]FDG PET) for 52 cortical regions included in a neuroanatomical atlas. We assessed group differences using ANCOVA models and further applied a cross-validated machine learning approach to identify the modality-specific brain regions that are most indicative of dementia status and assessed their diagnostic accuracy for group separation using receiver operating characteristic analyses.

RESULTS

In sMRI, atrophy of temporal and posterior-parietal areas allowed separating PDD from PD-CN (AUC = 0.77 ± 0.07), but diagnostic accuracy was poor for separating PD-MCI from PD-CN (0.57 ± 0.10). dMRI showed most pronounced diffusivity changes in the medial temporal lobe, which provided excellent diagnostic performance for PDD (AUC = 0.87 ± 0.06), and a more modest but still significant performance for PD-MCI (AUC = 0.71 ± 0.09). Finally, [18F]FDG PET revealed pronounced hypometabolism in posterior-occipital regions, which provided the highest diagnostic accuracies for both PDD (AUC = 0.89 ± 0.05) and PD-MCI (AUC = 0.78 ± 0.05). In statistical comparisons, both [18F]FDG PET (p < 0.001) and dMRI (p < 0.031) outperformed sMRI for detecting PDD and PD-MCI.

CONCLUSION

Among the tested modalities, [18F]FDG PET was most accurate for detecting cortical changes associated with cognitive impairment in PD, especially at early stages. Diffusion measurements may represent a promising MRI-based alternative.

α-Synuclein in Parkinson's Disease: From Bench to Bedside

α-Synuclein (α-syn), a pathological hallmark of PD, is emerging as a bridging element at the crossroads between neuro/immune-inflammatory responses and neurodegeneration in PD. Several evidence show that pathological α-syn accumulates in neuronal and non-neuronal cells (i.e., neurons, microglia, macrophages, skin cells, and intestinal cells) in central and peripheral tissues since the prodromal phase of the disease, contributing to brain pathology. Indeed, pathological α-syn deposition can promote neurogenic/immune-inflammatory responses that contribute to systemic and central neuroinflammation associated with PD. After providing an overview of the structure and functions of physiological α-syn as well as its pathological forms, we review current studies about the role of neuronal and non-neuronal α-syn at the crossroads between neuroinflammation and neurodegeneration in PD. In addition, we provide an overview of the correlation between the accumulation of α-syn in central and peripheral tissues and PD, related symptoms, and neuroinflammation. Special attention was paid to discussing whether targeting α-syn can represent a suitable therapeutical approach for PD.

Palliative Care in Parkinson's Disease

Palliative care aims to alleviate suffering from symptoms not often addressed in typical clinic visits, including nonmotor symptoms, psychosocial and caregiver burden, and advanced care planning. Palliative care is appropriate at any point in Parkinson's disease, but hospice care is an important potential therapy for end-of-life care. Palliative care remains underutilized, and work is underway on developing palliative care delivery models.

Leveraging animal models to understand non-motor symptoms of Parkinson's disease

Parkinson's disease is diagnosed based on motor symptoms, but non-motor symptoms of the disease, such as cognitive impairment, autonomic dysfunction, hyposmia, sleep disorders, and psychiatric disorders heavily impact patient and caregiver quality of life. It has proven challenging to faithfully reproduce and quantify these non-motor phenotypes. Indeed, many non-motor signs in animals that may phenotypically resemble features in patients may be caused by different mechanisms or may not be consistent within the same or similar models. In this review, we survey the existing literature on the assessment of non-motor signs in parkinsonian rodents and non-human primates. We highlight the gaps in our understanding and suggest how researchers might improve experimental designs to produce more meaningful results with the hope of better understanding the disease and developing better therapies.

The potential of brain organoids in addressing the heterogeneity of synucleinopathies

Synucleinopathies are a group of diseases characterized by neuronal and glial accumulation of α-synuclein (aSyn) linked with different clinical presentations, including Parkinson's disease (PD), Parkinson's disease with dementia (PDD), Dementia with Lewy Bodies (DLB) and Multiple system atrophy (MSA). Interestingly, the structure of the aSyn aggregates can vary across different synucleinopathies. Currently, it is unclear how the aSyn protein can aggregate into diverse structures and affect distinct cell types and various brain regions, leading to different clinical symptoms. Recent advances in induced pluripotent stem cells (iPSCs)-based brain organoids (BOs) technology provide an unprecedented opportunity to define the etiology of synucleinopathies in human brain cells within their three-dimensional (3D) context. In this review, we will summarize current advances in investigating the mechanisms of synucleinopathies using BOs and discuss the scope of this platform to define mechanisms underlining the selective vulnerability of cell types and brain regions in synucleinopathies.

Redefining Non-Motor Symptoms in Parkinson's Disease

Parkinson's disease involves widespread neurodegeneration that extends far beyond the basal ganglia, giving rise to a diverse range of non-motor symptoms that frequently emerge before motor onset. These include autonomic dysfunction, cognitive decline, neuropsychiatric disturbances, sleep-related disorders, and sensory deficits. Here, we synthesize current evidence on the anatomical, neurochemical, and network-level mechanisms that drive these symptoms, and we examine how they shape disease progression and clinical heterogeneity. We highlight the limitations of dopamine-centric models and advocate for a framework that treats non-motor symptoms as the disorder's primary, mechanistically distinct features. We also discuss how emerging technologies-such as multi-omic profiling, artificial intelligence, and network neuroscience-enable earlier identification, stratification of non-motor phenotypes, and the development of precision-based therapeutic strategies. Recognizing non-motor symptoms as central to Parkinson's disease redefines how the disorder should be diagnosed, studied, and treated.

Four questions to predict cognitive decline in de novo Parkinson's disease

Early identification of cognitive decline (CD) in de novo Parkinson's disease (PD) is crucial for choosing appropriate therapies and recruiting for clinical trials. However, existing prognostic models lack flexibility, scalability and require costly instrumentation. This study explores the utility of standard clinical questionnaires and criteria to predict CD in de novo PD. A total of 186 patients from the Parkinson Progression Markers Initiative (PPMI) and 48 patients from the Biomarkers of Parkinson's Disease project (BIO-PD) underwent clinical interviews, comprehensive tests, and questionnaires. A model based only on age of disease onset, history of stroke, history of fainting, and vocalization during dreams predicted CD in 2 and 4-year horizons with an area under curve (AUC) of 70% ± 10% standard deviation (cross-validated PPMI), 79% (overall PPMI), and 78% (validation in BIO-PD). This approach enables rapid preliminary screening using just four simple questions, achieving predictive accuracy comparable to instrumentation-based methods while reducing assessment time.

Virtual reality effects on balance and mobility in people with Parkinson's disease: A systematic review with meta-analysis

BACKGROUND

Specific Virtual Reality (VR) systems designed for rehabilitation and non-specific VR systems intended for entertainment are used in Parkinson's disease (PD) rehabilitation, but their effects are unclear. The extent to which these systems integrate neurorehabilitation principles for PD rehabilitation is unknown. Previous meta-analyses exist but data are lacking on the impact of VR on mobility.

OBJECTIVES

Primary aim: to perform a systematic review with meta-analysis comparing the effects of VR and conventional therapy (CT) on balance and mobility in people with PD. Secondary aim: to perform subgroup analyses on VR type, disease severity, and treatment duration.

METHODS

Randomized controlled trials comparing VR and CT effects on balance and mobility in adults with PD were selected from Pubmed and EMBASE until September 2024. Data were synthesized qualitatively and quantitatively using a standardized mean difference (SMD) with random-effects model. Subgroup analyses (VR type, disease severity, and treatment duration) and analysis of fulfilled neurorehabilitation principles were conducted. Risk of bias was assessed (PEDro checklist and Cochrane RoB-2).

RESULTS

Twenty-eight studies (12 countries) were included: 1151 participants, mean Hoehn & Yahr stage between 1.4 and 3.4, mean (SD) treatment duration 18.8 (11.5) hours in the qualitative analysis and 23 in the quantitative analysis. Overall risk of bias was high (10 studies), some concerns (13 studies), or low (5 studies). VR was more effective than CT for balance (630 participants; 11 studies; SMD 0.42; 95% CI, 0.19-0.65; P < 0.001) and as effective as CT for mobility (591 participants; 10 studies; SMD 0.18; 95% CI, -0.03 to 0.40; P = 0.09). Balance and mobility outcomes did not differ between specific and non-specific VR. Subgroup analyses found no significant differences.

CONCLUSIONS

VR improved balance in people with PD more than CT (low-certainty evidence). VR improved mobility similarly to CT (moderate-certainty evidence). VR games should integrate neurorehabilitation principles.

Association between cognitive and autonomic dysfunctions in patients with de novo Parkinson's disease

Cognitive decline is a common issue in Parkinson's disease (PD) and significantly affects patients' quality of life. This study explored the relationship between cognitive functions and dysautonomia in de novo PD. We reviewed records of newly diagnosed PD patients from July 2017 to September 2023 who underwent cognitive and autonomic assessments. Cognitive functions were measured using the Korean version of the Montreal Cognitive Assessment (MoCA-K) and the Seoul Neuropsychological Screening Battery, while autonomic functions were evaluated with the SCOPA-AUT questionnaire. Among 155 patients, 82 with de novo PD were included. The mild cognitive impairment (MCI) group exhibited higher SCOPA-AUT scores, particularly in gastrointestinal dysfunction. Multivariable logistic regression identified total SCOPA-AUT scores as significant predictors of MCI, even after adjusting for demographic and clinical factors. Partial correlation analysis showed significant negative associations between SCOPA-AUT scores and cognitive functions, such as memory and executive function. This study highlights a strong link between autonomic dysfunction, including gastrointestinal issues, and cognitive impairment in de novo PD. Monitoring dysautonomia in early-stage PD may aid in identifying patients at risk of cognitive decline.

Therapeutic Reference Range for Clozapine Plasma Levels in Parkinson's Disease or Dementia: A Systematic Review and Individual Participant Data Meta-analysis

Clozapine is a recommended treatment for psychotic symptoms in patients with Parkinson's disease (PD) and/or dementia. However, the therapeutic reference range for clozapine in these patients has not been established hitherto.The study was performed in three university hospitals in Germany and Switzerland, including clozapine-treated patients with PD and/or dementia. The primary outcome was tolerability based on reports of adverse drug reactions and/or changes in laboratory tests or electrocardiogram and/or clozapine discontinuation. We meta-analyzed demographic and pharmacokinetic parameters in patients tolerating clozapine well versus not. A meta-analytic summary receiver operating characteristic (SROC) to establish the clozapine upper level associated with poor tolerability was estimated.We analyzed a total of 99 patients suffering from PD (56.6%) and/or dementia (49.5%) with a mean age of 70.3±9.5 years and 41.4% females; poor tolerability was reported in 26 of 99 patients (26.3%). When comparing patients with and without poor tolerability, there were no differences in age, body mass index, sex, smoking, or clozapine dose, nor did we find statistically significant differences in clozapine levels (standardized mean difference 0.46, 95% confidence interval - 0.04 to 0.96, p=0.07), and heterogeneity was low (I2=0.0%). Clozapine blood levels above 193 ng/mL were associated with poor tolerability (SROC area-under-curve 0.6, sensitivity 39.7%, specificity 79.9%).One of four patients with PD and/or dementia treated with clozapine did not tolerate clozapine well, which was associated with a trend toward elevated clozapine concentrations. Monitoring drug levels may help to improve tolerability in these patients.

Challenges in studying air pollution to neurodegenerative diseases

Exposure to ambient air pollution is ubiquitous and unavoidable. While associations between air pollution and cardiometabolic diseases are well-established, its role in neurodegenerative diseases, such as Alzheimer's disease and related dementias (ADRD) and Parkinson's disease (PD), has only recently begun to emerge. This narrative review provides an overview of current findings and discusses challenges and opportunities for future epidemiologic research. Mechanistically, air pollution may contribute to ADRD and PD through neuroinflammation, oxidative stress, and cerebrovascular damage. Long-term exposure to high levels of air pollution may increase the risk of ADRD and PD. Over the past 20 years, more than 50 studies have examined air pollution and ADRD, while fewer studies have focused on PD. Although the estimated effects are modest in size, they translate into a substantial number of affected individuals due to the widespread nature of the exposure and an increasingly aging population worldwide. Future research should extend exposure periods to cover younger and middle ages, estimate the effects of long-term cumulative exposures, and evaluate moderators and mediators, such as diet, physical activity, green space, and noise. More studies are also needed to include large and diverse populations, including those with special vulnerabilities and emerging exposures like wildfire smoke.

PET tracer development for imaging α-synucleinopathies

Abnormal α-synuclein aggregation is a key neuropathological hallmark of α-synucleinopathies, such as Parkinson's disease (PD), multiple system atrophy (MSA), and several other neurological disorders, and closely contributes to pathogenesis. The primary characteristics of α-synucleinopathies are selective targeted neurodegeneration and the accumulation of Lewy pathologies. Specifically, α-synuclein positron emission tomography (PET) radiotracers target the fibrillar forms of the protein, thus enhancing early diagnosis and the evaluation of treatment effectiveness for various α-synucleinopathies. Therefore, in vivo detection of α-synuclein aggregates using targeted radiolabeled probes would aid in drug development, early diagnosis, and ongoing disease monitoring. As such, no promising α-synuclein biomarkers suitable for clinical applications have been reported. PET is a valuable non-invasive technique for imaging drug distribution in tissues and receptor occupancy at target sites in living animals and humans. Advances in PET biomarkers have significantly enhanced our understanding of the mechanisms underlying PD. This review summarizes recent ongoing efforts in the development of selective PET tracers for α-synuclein and discusses future perspectives.

Non-pharmacological rehabilitation for people living with advanced Parkinson's disease: A scoping review of interventions

BACKGROUND

Rehabilitation becomes increasingly important in the more advanced stages of Parkinson's Disease. As the disease reaches its more debilitating stages and pharmacological or surgical treatment becomes less relevant, non-pharmacological interventions including rehabilitation become key. Existing systematic interventions typically focus on individuals in the early to mid-stages of the disease. The objective of this scoping review was to identify and map the available evidence on non-pharmacological rehabilitation interventions for people living with advanced Parkinson's disease.

METHODS

This scoping review was conducted following the methodology for scoping reviews developed by the Joanna Briggs Institute. A systematic search was conducted in PubMed, EMBASE, CINAHL, and Cochrane. Studies published in English from 2000 to May 2024 were considered eligible and screened for relevance.

RESULTS

Thirteen studies were included. The majority of the interventions were experimental; one had a focus on feasibility and one had a mixed focus on effect and feasibility. Most interventions were referred to as either rehabilitation, training, or therapy, with the two feasibility interventions focusing on comprehensive assessment and referrals. The majority used modalities concerned with levels of functioning. Studies focusing on stage 4 (H&Y) Parkinson's disease were prominent.

CONCLUSIONS

This scoping review provides a foundational overview of existing non-pharmacological rehabilitation interventions for advanced Parkinson's disease, revealing a small yet diverse range of approaches, from single-disciplinary to multidisciplinary interventions. It offers initial insights that can point to areas where further research can solidify and expand effective, targeted care strategies for people living with advanced Parkinson's disease.

Cyclic Alternating Pattern of EEG Activities and Heart Rate Variability in Parkinson's Disease Patients during Deep Sleep

BACKGROUND

Sleep disturbance and autonomic dysfunction are often found in Parkinson's disease (PD) patients, but little is known about changes in cyclic alternating patterns (CAPs) of electroencephalographic (EEG) activities and heart rate variability (HRV) during deep sleep in PD patients.

OBJECTIVES

To investigate changes in EEG activities and HRV during CAPs and non-CAPs (NCAPs) of N3 sleep in PD patients.

METHODS

Polysomnographic (PSG) examinations were carried out on 18 PD patients and 18 healthy controls, and power spectral analysis of EEG activities and HRV during CAPs and NCAPs (the segment of sleep without CAPs for more than 60 seconds) of N3 sleep were carried out.

RESULTS

The percentages of N3 sleep with CAPs and CAP A1, as well as the CAP A1 index in the PD patients, were significantly smaller compared with the healthy controls. In addition, the power of α waves in NCAPs was significantly higher, while the powers of δ waves in Phase A and B of CAP A1 and A3, and NCAPs were significantly smaller. Furthermore, the durations of total δ waves and δ waves with an amplitude ≥75 μV were significantly shorter, and the low frequency (LF) power of HRV during CAPs and the LF/high frequency (HF) HRV ratio during both CAPs and NCAPs were significantly smaller.

CONCLUSIONS

The changes documented in EEG activities and HRV in PD patients during CAPs and NCAPs of N3 sleep compared with healthy controls suggest that N3 sleep quality and sympathetic function are compromised in PD patients.

Metabolomics in Parkinson's Disease and Correlation with Disease State

Changes in the level of metabolites, small molecules that are intermediates produced by metabolism or catabolism, are associated with developing diseases. Metabolite signatures in body fluids such as plasma, cerebrospinal fluid, urine, and saliva are associated with Parkinson's disease. Here, we discuss alteration of metabolites in the TCA cycle, pentose phosphate pathway, kynurenic network, and redox system. We also summarize the efforts of many research groups to differentiate between metabolite profiles that characterize PD motor progression and dyskinesia, gait and balance, and non-motor symptoms such as depression and cognitive decline. Understanding how changes in metabolites lead to progression in PD may allow for the identification of individuals at the earliest stage of the disease and the development of new therapeutic strategies.

Perturbations in levels of essential metals less severe in Parkinson's disease without dementia than in Parkinson's disease dementia

It is currently unknown why some individuals with Parkinson's disease (PD) go on to develop dementia [Parkinson's disease dementia (PDD)], whereas others do not. One possibility is differences in susceptibility to metallomic dysregulation. A previous study of the PDD brain identified substantive perturbations in metal levels, including severe multiregional decreases in Cu. The current work uses the same methods to ascertain whether this metallomic dysfunction is also present in the PD brain. To do this, tissue from 9 PD cases free of cognitive decline and 15 equivalent controls was obtained from 7 brain regions. Levels of Na, Mg, K, Ca, Mn, Fe, Cu, Zn, and Se were quantified using inductively coupled plasma mass spectrometry (ICP-MS). Multiple linear regression analysis was used to determine any potential confounder effects. Results were compared with those previously obtained for PDD. It was found that decreased Cu in the medulla was the only statistically significant case-control difference observed in the PD brain; this contrasts markedly with the widespread metallic dysfunction observed in PDD. PD and PDD cases were well separated by PCA analysis. In the PD cohort, tau Braak stage correlated with Cu concentrations in several regions, but these correlations were not retained when including PDD cases. There is a marked difference in the metallomic profiles of PD and PDD, with an almost complete lack of metallic involvement observed in the former. This resistance to metallomic dysfunction may contribute to resilience against cognitive impairment in individuals with PD who do not develop dementia.

Use of Robust Norming to Create a Sensitive Cognitive Summary Score in De Novo Parkinson's Disease: An Illustrative Example

BACKGROUND

Cognitive impairment is common at all stages of Parkinson's disease (PD), but there is no consensus on which neuropsychological tests to use or how to interpret cognitive battery results. A cognitive summary score (CSS) combines the richness of a neuropsychological battery with the simplicity of a single score.

OBJECTIVE

The objective of this study was to determine whether a CSS created using robust norming can detect early cognitive deficits in de novo, untreated PD.

METHODS

Baseline cognitive data from PD participants and healthy control participants (HCs) in the Parkinson's Progression Markers Initiative were used to (1) create a robust HC subgroup without cognitive decline, (2) generate regression-based z scores for six cognitive measures using this subgroup, and (3) create a CSS by averaging all z scores.

RESULTS

PD participants scored worse than HCs on all cognitive tests, with larger effects when compared with the robust HC subgroup rather than all HCs. Applying internally derived norms, the largest effects were for processing speed/working memory (Cohen's d = -0.55) and verbal episodic memory (Cohen's d = -0.48 and -0.52). Robust norming shifted PD performance from average (CSS z score = -0.01) to low average (CSS z score = -0.40), with a larger effect for the CSS (PD vs. robust HC subgroup; Cohen's d = -0.60) compared with individual tests.

CONCLUSIONS

Patients with PD perform worse cognitively than HCs, particularly in processing speed and verbal memory. Robust norming increases effect sizes and decreases PD scores to expected levels. The CSS outperformed individual tests and may detect cognitive changes in early PD, making it a useful outcome measure in clinical research. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Cortical α4β2-nicotinic acetylcholine receptors and cognitive decline in Parkinson's disease

BackgroundAutopsy and in vivo molecular imaging studies suggest altered binding of the α4β2-nicotinic cholinergic receptor (α4β2-nAChR) with cognitive dysfunction in Parkinson's disease (PD).ObjectiveTo determine the relationship between cortical and hippocampal binding of the α4β2-nAChR with [18F]XTRA PET, a high-affinity radiotracer that enables quantification of α4β2-nAChR in these regions, and cognitive function in individuals with PD.MethodsIndividuals with PD (N = 32) and age-similar, controls without PD or dementia (N = 10) completed a cognitive assessment and one 90-min, [18F]XTRA PET scan. Metabolite-corrected arterial input function radioactivity time-activity curves were generated to obtain total distribution volume (VT) across 12 regions of interest (ROIs). [18F]XTRA binding was compared 1) between controls and people with PD and 2) between controls, persons with PD with normal cognition (PD-NC), and persons with PD with MCI (PD-MCI).Results[18F]XTRA binding was higher in the occipital cortex of the combined group of PD participants compared to age-similar controls. No regions showed lower binding in PD. VT with, but not without, partial volume correction was different between controls, PD-NC, and PD-MCI groups, and this was driven by higher binding in PD-MCI compared to controls. Regression of regional VT on cognitive domain T-scores, adjusting for age, showed that worse performance in visual-spatial memory tasks was associated with higher VT in the precuneus and the entire parietal cortex.ConclusionsHigher α4β2-nAChR binding in posterior cortical regions is found in PD and associated with worse visual perception and memory, possibly due to lower receptor occupancy by endogenous acetylcholine.

Engrams across diseases: Different pathologies - unifying mechanisms?

Memories are our reservoir of knowledge and thus, are crucial for guiding decisions and defining our self. The physical correlate of a memory in the brain is termed an engram and since decades helps researchers to elucidate the intricate nature of our imprinted experiences and knowledge. Given the importance that memories have for our lives, their impairment can present a tremendous burden. In this review we aim to discuss engram malfunctioning across diseases, covering dementia-associated pathologies, epilepsy, chronic pain and psychiatric disorders. Current neuroscientific tools allow to witness the emergence and fate of engram cells and enable their manipulation. We further suggest that specific mechanisms of mnemonic malfunction can be derived from engram cell readouts. While depicting the way diseases act on the mnemonic component - specifically, on the cellular engram - we emphasize a differentiation between forms of amnesia and hypermnesia. Finally, we highlight commonalities and distinctions of engram impairments on the cellular level across diseases independent of their pathogenic origins and discuss prospective therapeutic measures.

Subregion-specific associations of the basal forebrain with sleep and cognition in Parkinson's disease

To elucidate the role of basal forebrain (BF) in non-motor symptoms of Parkinson's disease (PD), we investigated the association of sleep quality and cognition with BF volume and functional connectivity. The gray matter volume of the anterior intermediate part (Ch4ai) and the anterior lateral part (Ch4al) of the nucleus basalis Meynert were negatively associated with the PSQI global score. The posterior part of the nucleus basalis Meynert (Ch4p) volume was positively associated with visuospatial, memory, and executive functions. The PSQI global score correlated positively with functional connectivity from the Ch4al to the posterior cingulate, inferior parietal, anterior temporal, and medial prefrontal cortices, which correspond to the default mode network. Our results demonstrated that reduced volume of the anterior portion of the Ch4 and its aberrantly increased functional connectivity with the default mode network were closely related to poor overall sleep quality, while reduced volume of the posterior portion of the Ch4 was associated with decreased cognitive function in PD.

The role of Apolipoprotein E4 on cognitive impairment in Parkinson's disease and Parkinsonisms

Cognitive impairment is a prevalent non-motor symptom of Parkinson's disease (PD), increasing the risk of dementia as the disease progresses. Despite its clinical significance, the etiology of cognitive impairment in PD remains unclear. Apolipoprotein E4 (APOE4), a well-known genetic risk factor of Alzheimer's disease, has been studied for its potential role in PD-related cognitive impairment. However, findings have been conflicting and thus inconclusive, highlighting a need to critically evaluate the current research. Several studies using neuroimaging modalities have explored the brains of individuals with PD and atypical parkinsonian disorders who have APOE4. Some of these studies have identified distinct neuropathological changes that have been previously reported to be associated with cognitive impairments in those with Parkinsonisms. Here, we review the role of APOE4 on cognitive impairment in PD and atypical Parkinsonisms using neuroimaging evidence. We will examine how APOE4 may contribute to pathological changes within the brain and its association with cognitive impairment.

Parkinson's disease and glucose metabolism impairment

Parkinson's disease (PD) is the second most common neurodegenerative disorder. PD patients exhibit varying degrees of abnormal glucose metabolism throughout disease stages. Abnormal glucose metabolism is closely linked to the PD pathogenesis and progression. Key glucose metabolism processes involved in PD include glucose transport, glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, the pentose phosphate pathway, and gluconeogenesis. Recent studies suggest that glucose metabolism is a potential therapeutic target for PD. In this review, we explore the connection between PD and abnormal glucose metabolism, focusing on the underlying pathophysiological mechanisms. We also summarize potential therapeutic drugs related to glucose metabolism based on results from current cellular and animal model studies.

Progress and prospects of Parkinson's disease with depression research: A global bibliometric analysis based on CiteSpace

BACKGROUND

Parkinson's disease (PD) is a common neurodegenerative disorder marked by motor impairments such as stiffness, involuntary shaking, and slowed movement. In addition, PD patients frequently experience nonmotor symptoms, especially depression. This study uses a mixed-methods scientometric analysis to review global research trends and advancements in PD and depression. This analysis is vital for clinicians, researchers, and policymakers, identifying knowledge gaps and directing future research efforts.

METHODS

We conducted a comprehensive literature review on PD and depression using the Web of Science database from 2004 to 2023, facilitated by CiteSpace 6.1.R6. Our analysis examined collaborations among authors, institutions, countries, and keywords, incorporating insights from RCTs and qualitative studies. We calculated effect sizes and confidence intervals with precision. Ethical approval was not required as the study used publicly available data without personal information.

RESULTS

Our analysis included 3048 research papers and 915 reviews, involving 17,927 authors and 12,466 institutions. The United States and the University of Toronto led in publications. Studies revealed significant effect sizes with narrow confidence intervals, particularly on the prevalence and impact of depression in PD patients. High-frequency keywords included "Parkinson's disease," "depression," "quality of life," "non-motor symptom," and "dementia." Visual mapping identified critical research nodes and future directions.

CONCLUSION

Over the past 2 decades, research on the PD-depression link has accelerated. Our analysis highlights prevailing trends and critical areas, providing evidence-based recommendations for therapeutic strategies. This study offers valuable insights for clinicians and researchers, emphasizing future research priorities to improve patient outcomes.

Bidirectional relationship between depression and activities of daily living and longitudinal mediation of cognitive function in patients with Parkinson's disease

Objective

To investigate the bidirectional relationship between depression and activities of daily living (ADL) in Parkinson's disease (PD) patients and explore the mediating role of cognitive function over time.

Methods

Data from 892 PD patients from the Parkinson's Progression Markers Initiative (PPMI) database were included in this study, and depression, cognitive function, and ADL were measured using the Geriatric Depression Scale (GDS-15), Montreal Cognitive Assessment Scale (MoCA), and Unified Parkinson's Disease Rating Scale, Part II (UPDRS II) respectively. The cross-lagged panel model (CLPM) was employed to analyze the reciprocal relationship between depression and ADL. Then, we explored the mediating role of cognitive function in the bidirectional relationship between depression and ADL in patients with PD, and the mediation effect test was carried out using a bias-corrected nonparametric percentile bootstrap approach.

Results

Depression in patients with PD predicted their subsequent ADL (β = 0.079, p < 0.01), and ADL also predicted their subsequent depression (β = 0.069, p < 0.05), In addition, Bootstrap analysis showed that cognitive function played a significant mediating role in prediction of depression to ADL in patients with PD (β = 0.006, p = 0.074, 95%CI = 0.001 ~ 0.014), and cognitive function also played a significant mediating role in prediction of depression to ADL (β = 0.006, p = 0.067, 95%CI = 0.001 ~ 0.013).

Conclusion

There is a bidirectional relationship between depression and ADL in patients with PD. Furthermore, we found that cognitive function mediates the relationship that exists between depression and ADL in patients with PD. Interventions aimed at enhancing cognitive function could potentially lessen the vicious cycle of depression and ADL in PD, thus improving patient quality of life (QOL).

From mechanisms to future therapy: a synopsis of isolated REM sleep behavior disorder as early synuclein-related disease

Parkinson disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy are synucleinopathies, characterized by neuronal loss, gliosis and the abnormal deposition of α-synuclein in vulnerable areas of the nervous system. Neurodegeneration begins however several years before clinical onset of motor, cognitive or autonomic symptoms. The isolated form of REM sleep behavior disorder (RBD), a parasomnia with dream enactment behaviors and excessive muscle activity during REM sleep, is an early stage synucleinopathy. The neurophysiological hallmark of RBD is REM sleep without atonia (RWSA), i.e. the loss of physiological muscle atonia during REM sleep. RBD pathophysiology is not fully clarified yet, but clinical and basic science suggest that ɑ-syn pathology begins in the lower brainstem where REM atonia circuits are located, including the sublaterodorsal tegmental/subcoeruleus nucleus and the ventral medulla, then propagates rostrally to brain regions such as the substantia nigra, limbic system, cortex. Genetically, there is only a partial overlap between RBD, PD and DLB, and individuals with iRBD may represent a specific subpopulation. A genome-wide association study identified five loci, which all seem to revolve around the GBA1 pathway. iRBD patients often show subtle motor, cognitive, autonomic and/or sensory signs, neuroimaging alterations as well as biofluid and tissue markers of neurodegeneration (in particular pathologic α-synuclein aggregates), which can be useful for risk stratification. Patients with iRBD represent thus the ideal population for neuroprotective/neuromodulating trials. This review provides insights into these aspects, highlighting and substantiating the central role of iRBD in treatment development strategies for synucleinopathies.

Examining Agreement in Psychotic Symptom Assessment: Insights from Parkinson's Disease Dementia Dyads

BACKGROUND

Psychosis and cognitive decline often co-occur in Parkinson's Disease (PD), which complicates assessment.

OBJECTIVE

We measured agreement between patients with PD and dementia (PDD) and care partners (CPs) in their independent evaluation of PD-related psychotic symptoms.

METHODS

We compared responses to a PD psychosis rating scale (SAPS-PD) in 21 dyads of patients with PDD and cognitively normal CPs. We assessed the concordance of responses using the intraclass correlation coefficient (ICC). Following the psychosis assessment, the clinician used all available information and adjudicated who provided the most reliable responses.

RESULTS

Dyads demonstrated poor concordance in summary scores (ICC = 0.464). Six of the nine individual items had poor agreement. The clinician adjudicated the patient's response as the more reliable in 71.4% of cases.

CONCLUSIONS

Although many psychotic symptoms are internal and not observable, in the context of PDD, both patient and CP inputs are valuable, but final adjudication favors patient responses.

Insomnia in Parkinson's Disease: Causes, Consequences, and Therapeutic Approaches

Sleep disorders represent prevalent non-motor symptoms in Parkinson's disease (PD), affecting over 90% of the PD population. Insomnia, characterized by difficulties in initiating and maintaining sleep, emerges as the most frequently reported sleep disorder in PD, with prevalence rates reported from 27 to 80% across studies. Insomnia not only significantly impacts the quality of life of PD patients but is also associated with cognitive impairment, motor disabilities, and emotional deterioration. This comprehensive review aims to delve into the mechanisms underlying insomnia in PD, including neurodegenerative changes, basal ganglia beta oscillations, and circadian rhythms, to gain insights into the neural pathways involved. Additionally, the review explores the risk factors and comorbidities associated with insomnia in PD, providing valuable insights into its management. Special attention is given to the challenges faced by healthcare providers in delivering care to PD patients and the impact of caregiving roles on patients' quality of life. Overall, this review provides a comprehensive understanding of insomnia in PD and highlights the importance of addressing this common sleep disorder in PD patients.

Detailed investigation of the levodopa response rates in distinct motor subscores in Parkinson's disease patients with and without STN-DBS

AIM

To investigate the levodopa response (LDR) in a detailed manner in Parkinson's disease (PD) patients with and without STN-DBS. In this respect, we sought to evaluate the effect of LDR on distinct motor symptoms one by one.

METHODS

The data of all consecutive PD patients who visited our movement disorders outpatient clinics at Etlik City Hospital between January 2023 and January 2024 were retrospectively evaluated. We enrolled patients whose full clinical assessments were available. The LDR was evaluated according to a previously described method.

RESULTS

We included 194 PD patients in this study [49 STN-DBS (+) patients, 145 STN-DBS (-) patients]. The disease duration was greater in the STN-DBS group, as expected (12 y, 5 y, p = 0.00). The LDR ratios for the total score and subitem scores of the MDS-UPDRS-3 were similar between the patient groups. All the subscores of the MDS-UPDRS-3 were significantly lower for the 'ON' medication state than for the 'OFF' medication state in both patient groups.

CONCLUSIONS

We demonstrated similar LDR rates for all motor subitems in patients with and without STN-DBS in a detailed manner. Our findings demonstrate the benefit of dopaminergic treatment on distinct motor symptoms in patients with STN-DBS.

Cholinergic Denervation Patterns in Parkinson's Disease Associated With Cognitive Impairment Across Domains

Cognitive impairment is considered to be one of the key features of Parkinson's disease (PD), ultimately resulting in PD-related dementia in approximately 80% of patients over the course of the disease. Several distinct cognitive syndromes of PD have been suggested, driven by different neurotransmitter deficiencies and thus requiring different treatment regimes. In this study, we aimed to identify characteristic brain covariance patterns that reveal how cholinergic denervation is related to PD and to cognitive impairment, focusing on four domains, including attention, executive functioning, memory, and visuospatial cognition. We applied scaled sub-profile model principal component analysis to reveal cholinergic-specific disease-related and cognition-related covariance patterns using [18F]fluoroethoxybenzovesamicol PET imaging. Stepwise logistic regression was applied to predict disease state (PD vs. healthy control). Linear regression models were applied to predict cognitive functioning within the PD group, for each cognitive domain separately. We assessed the performance of the identified patterns with leave-one-out cross validation and performed bootstrapping to assess pattern stability. We included 34 PD patients with various levels of cognitive dysfunction and 10 healthy controls, with similar age, sex, and educational level. The disease-related cholinergic pattern was strongly discriminative (AUC 0.91), and was most prominent in posterior brain regions, with lower tracer uptake in patients compared to controls. We found largely overlapping cholinergic-specific patterns across cognitive domains, with positive correlations between tracer uptake in the opercular cortex, left dorsolateral prefrontal cortex and posterior cingulate gyrus, among other regions, and attention, executive, and visuospatial functioning. Cross validation showed significant correlations between predicted and measured cognition scores, with the exception of memory. We identified a robust structural covariance pattern for the assessment of cholinergic dysfunction related to PD, as well as overlapping cholinergic patterns related to attentional, executive- and visuospatial impairment in PD patients.

Managing cognitive impairment in Parkinson's disease: an update of the literature

INTRODUCTION

Cognitive impairment in Parkinson's disease (PD) substantially affects patient outcomes, function, and quality of life. PD-related cognitive dysfunction is often heterogeneous in clinical presentation and rates of progression. As cognitive changes occur in many people with PD, it is essential to evaluate cognition, provide education, and implement management strategies for cognitive symptoms.

AREAS COVERED

This article describes the symptomatology, epidemiology, risk factors, and pathobiology of cognitive impairment in PD. Additionally, the article provides an overview of evidence-based management and other therapeutic and coping strategies for cognitive impairment and dementia in PD. Comment is offered on challenges and opportunities for trials and emerging therapeutics targeting cognitive symptoms or decline.

EXPERT OPINION

While our understanding of cognitive dysfunction in PD has grown, effective and safe therapeutics are still needed to not only treat cognitive impairment and dementia symptomatically but also slow down or prevent cognitive decline. Further research is needed to elucidate the pathobiology of PD cognitive impairment, develop validated biomarkers reflecting cognitive change, and ultimately, integrate clinical and biological frameworks. Consensus regarding cognitive evaluations, definitions, and criteria of cognitive impairment, evaluating functional abilities in the context of cognitive impairment, and determining optimal outcome measures for clinical trials remain unmet needs.

An Acetylcholine M1 Receptor-Positive Allosteric Modulator (TAK-071) in Parkinson Disease With Cognitive Impairment: A Phase 2 Randomized Clinical Trial

Importance

Fall risk and cognitive impairment are prevalent and burdensome in Parkinson disease (PD), requiring efficacious, well-tolerated treatment.

Objective

To evaluate the safety and efficacy of TAK-071, a muscarinic acetylcholine M1 positive allosteric modulator, in participants with PD, increased fall risk, and cognitive impairment.

Design, Setting, and Participants

This phase 2 randomized double-blind placebo-controlled crossover clinical trial was conducted from October 21, 2020, to February 27, 2023, at 19 sites in the US. Participants included patients aged 40 to 85 years with a diagnosis of PD, with at least 1 fall in the prior 12 months, with a Montreal Cognitive Assessment score of 11 to 26, and receiving stable antiparkinsonian medications and no acetylcholinesterase inhibitors.

Intervention

One-to-one randomization to once-daily oral TAK-071 or placebo for 6 weeks, followed by washout and 6 weeks of crossover treatment.

Main Outcomes and Measures

The primary end point was change from baseline in gait variability (stride time variability [STV]) during a 2-minute walk test with or without cognitive load. The secondary efficacy end point was change from baseline in a cognitive composite score consisting of tests of attention, executive function, and memory.

Results

Among the 54 participants included in the analysis, 45 (83%) were male, mean (SD) age was 69.7 (6.9) years, and median Montreal Cognitive Assessment score was 24 (range, 17-26). After 6 weeks of treatment, the primary outcome was negative: the change from baseline in STV did not differ between participants receiving TAK-071 or placebo, with cognitive load (geometric mean ratio, 1.15; 95% CI, 0.94-1.41; P = .16) or without cognitive load (geometric mean ratio, 1.02; 95% CI, 0.88-1.18; P = .78). TAK-071 improved the secondary efficacy outcome (cognitive composite score) vs placebo. The least squares mean difference of the change from baseline was 0.22 (95% CI, 0.05-0.38; P = .01). Treatment-emergent adverse events occurred in 18 of 49 participants (37%) while receiving placebo and in 19 of 53 (36%) while receiving TAK-071. Four participants (8%) receiving TAK-071 had adverse events resulting in withdrawal of study drug; 4 had gastrointestinal tract adverse events.

Conclusions and Relevance

In this study, in participants with PD, risk for falls, and cognitive impairment, TAK-071 was well-tolerated. The treatment did not improve the primary outcome of gait variability, but did improve cognition compared with placebo. Larger and longer studies in more diverse populations are needed to better understand the safety and efficacy of TAK-071 in broader populations.

Trial Registration

ClinicalTrials.gov Identifier: NCT04334317.

From Night to Light: A Bibliometric Analysis of the Global Research Trajectory of Sleep Disorders in Parkinson's Disease

Purpose

Sleep disorders are prevalent non-motor symptoms in patients with Parkinson's disease (PD), significantly diminishing the overall quality of life for patients and potentially accelerating the deterioration of motor and cognitive functions, accelerating disease progression. Despite increasing research on sleep disorders in PD, a comprehensive analysis of the knowledge structure and key issues in this field are still lacking. This study aims to identify research hotspots and emerging trends related to sleep disorders in PD through a detailed bibliometric analysis.

Patients and Methods

On October 1, 2024, an extensive search was conducted in the Web of Science Core Collection (WOSCC) database to gather relevant literature on sleep disorders in PD. Bibliometric and knowledge mapping analyses were performed using CiteSpace, VOSviewer, and bibliometrix.

Results

Between January 1, 2004, and October 1, 2024, a total of 3,655 publications on sleep disorders in PD were published by 3,387 institutions across 87 countries. The volume of publications has shown a steady increase, a trend projected to continue. Current research is primarily centered on Neurosciences, Pharmacology, and Clinical Neurology. Emerging trends involve comprehensive evaluations of sleep, early diagnosis and prevention of various sleep disorder subtypes in PD, and advancing research through animal models to develop effective therapies. Emerging keywords include machine learning, sleep quality, biomarkers, covid-19, and mouse model.

Conclusion

This bibliometric analysis sheds light on the global landscape of PD-related sleep disorder research over the past two decades, highlighting key countries, institutions, authors, and journals driving advancements in the field. Moreover, it uncovers pivotal research hotspots and emerging trends, offering valuable insights and guidance for scholars engaged in this area.

Differences and contributors to global cognitive performance in the underrepresented Latinx Parkinson's disease population

Objective: Despite significant progress in understanding the factors influencing cognitive function in Parkinson's disease (PD), there is a notable gap in data representation for the Latinx population. This study aims to evaluate the contributors to and disparities in cognitive performance among Latinx patients with PD. Methods: A retrospective analysis was conducted based on cross-sectional data encompassing demographic, environmental, motor, and non-motor disease characteristics from the Latin American Research Consortium on the Genetics of PD (LARGE-PD) and the Parkinson's Progression Markers Initiative (PPMI) cohorts. Linear regression multivariable models were applied to identify variables affecting Montreal Cognitive Assessment (MoCA) scores, accounting for age, sex, and years of education. Results: The analysis comprised of 3,054 PD patients (2,041 from LARGE-PD and 1,013 from PPMI) and 1,303 Latinx-controls. Latinx-PD patients (mean age 63.0 ± 11.8, 56.8% male) exhibited a significantly lower average MoCA score (p < .001) compared to white Non-Hispanic PD patients from PPMI (mean age 67.5 ± 9.9, 61.7% male). This difference persisted when comparing the Latinx-PD to the Latinx-controls (mean age 58.7 ± 9.3, 33.2% male; p < .001). Factors significantly associated with better MoCA scores in Latinx-PD included unilateral symptom onset (p = .009), and higher educational attainment (p < .001). Conversely, those associated with worse scores included the use of dopamine agonists (p = .01), previous tobacco use (p = .01), older age (p < .001), and a higher Hoehn and Yahr scale score (p < .001). Conclusions: Latinx-PD patients demonstrated significantly lower cognitive scores compared to their white non-Hispanic PD counterparts and Latinx-controls. These results highlight the importance of interpreting MoCA scores in a nuanced manner within diverse populations.

Cognitive impairment in PSP compared with PD: assessment by clinical subtype and longitudinal change

Background

Longitudinal studies investigating cognitive function changes in patients with progressive supranuclear palsy (PSP) are limited. The variability of cognitive impairment across clinical subtypes of PSP remains unclear.

Objective

This study aimed to compare the longitudinal changes in cognitive function between patients with PSP and Parkinson's disease (PD) and to assess differences in cognitive impairment among PSP subtypes.

Methods

A retrospective observational study was conducted using neuropsychological testing data from patients with PSP and PD admitted to our hospital.

Results

The study included 38 patients with PD and 41 patients with PSP (23 PSP-Richardson's syndrome, 14 PSP-progressive gait freezing (PSP-PGF), 3 PSP-Parkinsonism and 1 PSP-predominant corticobasal syndrome). At baseline, cognitive function was significantly lower in the PSP group than in the PD group. Over 12 months, patients with PSP exhibited significant declines in multiple cognitive domains, whereas no significant changes were observed in the PD group. Among PSP subtypes, PSP-RS showed a faster rate of cognitive decline than PD, while PSP-PGF demonstrated a lower progression than PSP-RS.

Conclusion

PSP is associated with progressive cognitive impairment, with rates of decline varying by subtype. PSP-PGF exhibited a slower progression than PSP-RS. Clinical management should consider subtype-specific differences in cognitive prognosis to tailor treatment and care.

Plasma fibronectin is a prognostic biomarker of disability in Parkinson's disease: a prospective, multicenter cohort study

In a prospective longitudinal study with 218 Parkinson's disease (PD) patients in the discovery cohort and 84 in the validation cohort, we aimed to identify novel blood biomarkers predicting disability milestones in PD. Through Least Absolute Shrinkage and Selection Operator-Cox (Lasso-Cox) regression, developed nomogram predictive model and Linear mixed-effects models, we identified low level of plasma fibronectin (pFN) as one of the best-performing risk markers in predicting disability milestones. A low level of pFN was associated with a short milestone-free survival period in PD. Longitudinal analysis showed an annual decline in the rate of pFN was significantly associated with the annual elevation rate in the Hoehn-Yahr stage. Moreover, pFN level was negatively correlated with phosphorylated α-synuclein, and a low level of pFN was associated with BBB disruption in the striatum on neuroimaging, providing evidence for pFN's role in PD progression. We finally identified pFN as a novel blood biomarker that predicted first-milestone disability in PD.

Guidelines for Parkinson's disease management part II: consensus from the movement disorders scientific department of the Brazilian Academy of Neurology - non-motor symptoms

The treatment of Parkinson's disease (PD) is a challenge, especially because it is considered highly individualized. The Brazilian Academy of Neurology (ABN) has identified the need to disseminate knowledge about its management, adapting the best evidence to the Brazilian population. The present article aims to report the recommendations for the treatment of non-motor symptoms of PD, developed by a group of specialists in movement disorders from the ABN's scientific department. In 2021, the first part, referring to the motor symptoms of PD, was published. The main non-motor symptoms were addressed-among them neuropsychiatric symptoms, such as depression, anxiety, cognitive alteration, and psychosis-as well as the possible recommended therapies and medications used to control pain, sleep disorders, and dysautonomia.