Predictors of post stroke cognitive impairment: VITATOPS cognition substudy

INTRODUCTION

Post stroke cognitive impairment (PSCI) is a common complication of ischemic stroke. PSCI can involve different depending on clinical and stroke related characteristics. The aim of this study is to determine the factors associated with impairments in specific cognitive domains.

METHODS

The Vitamins to Prevent Stroke (VITATOPS) trial is a large, multinational randomised controlled trial. In this substudy, consecutive patients admitted for ischaemic stroke or transient ischaemic attack (TIA) at a tertiary hospital in Singapore were included. PSCI was defined as impairment of any of the six cognitive subgroups - visuoconstruction, attention, verbal memory, language, visual memory and visuomotor function - that were assessed annually for up to five years. Univariate and multivariate Cox proportional hazard models were used to determine factors associated with impairments in each of these cognitive domains.

RESULTS

A total of 736 patients were included in this study, of which 173 (23.5 %) developed cognitive impairment. Out of the six cognitive domains, the greatest proportion of patients had an impairment in visuoconstruction (26.4 %) followed by attention (19.8 %), verbal memory (18.3 %), language (17.5 %), visual memory (17.3 %) and visuomotor function (14.8 %). Patients with posterior circulation cerebral infarction (POCI) as the index stroke subtype had higher rates of cognitive impairment. Further subgroup analyses show that Indian race and advanced age were predictive of language impairment, whilst fewer years of education and POCI were predictive of verbal memory impairment. POCI was predictive of visual memory impairment, and advanced age and POCI were predictive of visuomotor function impairment.

CONCLUSION

We identified visuoconstruction and attention domains to be the most affected in our Asian cohort of PSCI. Advanced age, lower levels of education, posterior circulation strokes and concomitant comorbidities such as peripheral artery disease are independent predictors of PSCI.

Role of dopamine in the pathophysiology of Parkinson's disease

A pathological feature of Parkinson's disease (PD) is the progressive loss of dopaminergic neurons and decreased dopamine (DA) content in the substantia nigra pars compacta in PD brains. DA is the neurotransmitter of dopaminergic neurons. Accumulating evidence suggests that DA interacts with environmental and genetic factors to contribute to PD pathophysiology. Disturbances of DA synthesis, storage, transportation and metabolism have been shown to promote neurodegeneration of dopaminergic neurons in various PD models. DA is unstable and can undergo oxidation and metabolism to produce multiple reactive and toxic by-products, including reactive oxygen species, DA quinones, and 3,4-dihydroxyphenylacetaldehyde. Here we summarize and highlight recent discoveries on DA-linked pathophysiologic pathways, and discuss the potential protective and therapeutic strategies to mitigate the complications associated with DA.

Isolated Cervical Dystonia: Diagnosis and Classification

This document presents a consensus on the diagnosis and classification of isolated cervical dystonia (iCD) with a review of proposed terminology. The International Parkinson and Movement Disorder Society Dystonia Study Group convened a panel of experts to review the main clinical and diagnostic issues related to iCD and to arrive at a consensus on diagnostic criteria and classification. These criteria are intended for use in clinical research, but also may be used to guide clinical practice. The benchmark is expert clinical observation and evaluation. The criteria aim to systematize the use of terminology as well as the diagnostic process, to make it reproducible across centers and applicable by expert and non-expert clinicians. Although motor abnormalities remain central, increasing recognition has been given to nonmotor manifestations, which are incorporated into the current criteria. Three iCD presentations are described in some detail: idiopathic (focal or segmental) iCD, genetic iCD, and acquired iCD. The relationship between iCD and isolated head tremor is also reviewed. Recognition of idiopathic iCD has two levels of certainty, definite or probable, supported by specific diagnostic criteria. Although a probable diagnosis is appropriate for clinical practice, a higher diagnostic level may be required for specific research studies. The consensus retains elements proven valuable in previous criteria and omits aspects that are no longer justified, thereby encapsulating diagnosis according to current knowledge. As understanding of iCD expands, these criteria will need continuous revision to accommodate new advances. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Targeting gasdermin E in neurodegenerative diseases

Neel et al. identified pathophysiologic clues linking gasdermin-E (GSDME) with frontotemporal dementia and amyotrophic lateral sclerosis.¹ Therapeutic studies targeting GSDME may provide a viable approach for neurodegenerative diseases.

Plasma Soluble ST2 Levels Are Higher in Neurodegenerative Disorders and Associated with Poorer Cognition

BACKGROUND

Suppressor of tumorgenicity 2 (ST2) is highly expressed in brain tissue and is a receptor for interleukin 33 (IL-33). ST2 exists in two forms, a transmembrane receptor (ST2L) and a soluble decoy receptor (sST2). IL-33 binds to ST2L, triggering downstream signaling pathways involved in amyloid plaque clearance. Conversely, sST2 binds competitively to IL-33, attenuating its neuroprotective effects. High sST2 levels have been reported in mild cognitive impairment (MCI) and Alzheimer's disease (AD), suggesting that the IL-33/ST2 signaling pathway may be implicated in neurodegenerative diseases.

OBJECTIVE

To investigate plasma sST2 levels in controls and patients with MCI, AD, frontotemporal dementia (FTD), and Parkinson's disease (PD).

METHODS

Plasma sST2 levels were measured using ELISA in 397 subjects (91 HC, 46 MCI, 38 AD, 28 FTD, and 194 PD). Cerebrospinal fluid (CSF) levels of sST2 were measured in 22 subjects. Relationship between sST2 and clinical outcomes were analyzed.

RESULTS

Plasma sST2 levels were increased across all disease groups compared to controls, with highest levels seen in FTD followed by AD and PD. Dementia patients with higher sST2 had lower cross-sectional cognitive scores in Frontal Assessment Battery and Digit Span Backward. At baseline, PD-MCI patients had higher sST2, associated with worse attention. In the longitudinal PD cohort, higher sST2 significantly associated with decline in global cognition and visuospatial domains. Plasma sST2 levels correlated with CSF sST2 levels.

CONCLUSION

Plasma sST2 is raised across neurodegenerative diseases and is associated with poorer cognition. Higher baseline sST2 is a potential biomarker of disease severity in neurodegeneration.

B-vitamin supplementation on mitigating post-stroke cognition and neuropsychiatric sequelae: A randomized controlled trial

BACKGROUND AND PURPOSE

A third of stroke patients suffer from post-stroke cognitive decline, depressive symptoms, and anxiety symptoms. B-vitamin supplementation provides a possible safe and affordable treatment to mitigate post-stroke neuropsychiatric sequelae via reducing homocysteine levels. Our study aims to examine the effect of B-vitamin supplementation in the prevention of post-stroke cognitive decline, depressive symptoms, and anxiety symptoms. Our secondary aims were to investigate associations between baseline factors and the three outcomes.

METHODS

Patients were recruited as part of a Singaporean substudy of a randomized controlled trial that examined the effect of B-vitamin supplementation on recurrent cardiovascular events. Cognitive decline, depressive symptoms, and anxiety symptoms were assessed with neuropsychological assessments and Hospital Anxiety and Depression Scale 6 monthly. Cox regression analyses were performed to determine treatment efficacy. Logistic regression used to examine factors associated with cognitive decline, depressive symptoms, and anxiety symptoms.

RESULTS

A total of 707 were included in the analyses. Survival and hazards ratio analysis showed no treatment effect of B-vitamins on cognitive decline, depressive symptoms, and anxiety symptoms. Cognitive decline was only associated with age. Depressive symptoms were associated with large anterior cerebral infarcts and hyperlipidemia.

CONCLUSIONS

Our study showed no benefit of supplementation with B-vitamins for post-stroke cognitive decline, depressive symptoms, or anxiety symptoms. Depressive symptoms were associated with larger anterior cerebral infarcts, which may be reflective of the disability associated with larger infarcts.

Using the consolidated framework for implementation research to guide a pilot of implementing an institution level patient informed consent process for clinical research at an outpatient setting

BACKGROUND

In Singapore, research teams seek informed patient consent on an ad hoc basis for specific clinical studies and there is typically a role separation between operational and research staff. With the enactment of the Human Biomedical Research Act, there is increased emphasis on compliance with consent-taking processes and research documentation. To optimize resource use and facilitate long-term research sustainability at our institution, this study aimed to design and pilot an institution level informed consent workflow (the "intervention") that is integrated with clinic operations.

METHODS

We used the Consolidated Framework for Implementation Research (CFIR) as the underpinning theoretical framework and conducted the study in three stages: Stage 1, CFIR constructs were used to systematically identify barriers and facilitators of intervention implementation, and a simple time-and-motion study of the patient journey was used to inform the design of the intervention; Stage 2, implementation strategies were selected and mapped to the Expert Recommendations for Implementing Change (ERIC) taxonomy; Stage 3, we piloted and adapted the implementation process at two outpatient clinics and evaluated implementation effectiveness through patient participation rates.

RESULTS

We identified 15 relevant CFIR constructs. Implementation strategies selected to address these constructs were targeted at three groups of stakeholders: institution leadership (develop relationships, involve executive boards, identify and prepare champions), clinic management team (develop relationships, identify and prepare champions, obtain support and commitment, educate stakeholders), and clinic operations staff (develop relationships, assess readiness, conduct training, cyclical tests of change, model and simulate change, capture and share local knowledge, obtain and use feedback). Time-and-motion study in clinics identified the pre-consultation timepoint as the most appropriate for the intervention. The implementation process was adapted according to clinic operations staff and service needs. At the conclusion of the pilot, 78.3% of eligible patients provided institution level informed consent via the integrated workflow implemented.

CONCLUSIONS

Our findings support the feasibility of implementing an institution level informed consent workflow that integrates with service operations at the outpatient setting to optimize healthcare resources for research. The CFIR provided a useful framework to identify barriers and facilitators in the design of the intervention and its implementation process.

Analysis of clinically relevant variants from ancestrally diverse Asian genomes

Asian populations are under-represented in human genomics research. Here, we characterize clinically significant genetic variation in 9051 genomes representing East Asian, South Asian, and severely under-represented Austronesian-speaking Southeast Asian ancestries. We observe disparate genetic risk burden attributable to ancestry-specific recurrent variants and identify individuals with variants specific to ancestries discordant to their self-reported ethnicity, mostly due to cryptic admixture. About 27% of severe recessive disorder genes with appreciable carrier frequencies in Asians are missed by carrier screening panels, and we estimate 0.5% Asian couples at-risk of having an affected child. Prevalence of medically-actionable variant carriers is 3.4% and a further 1.6% harbour variants with potential for pathogenic classification upon additional clinical/experimental evidence. We profile 23 pharmacogenes with high-confidence gene-drug associations and find 22.4% of Asians at-risk of Centers for Disease Control and Prevention Tier 1 genetic conditions concurrently harbour pharmacogenetic variants with actionable phenotypes, highlighting the benefits of pre-emptive pharmacogenomics. Our findings illuminate the diversity in genetic disease epidemiology and opportunities for precision medicine for a large, diverse Asian population.

Clinical Outcomes After Ventriculo-Peritoneal Shunting in Patients With Classic vs. Complex NPH

Objective

Normal pressure hydrocephalus (NPH) is a neurological condition characterized by a clinical triad of gait disturbance, cognitive impairment, and urinary incontinence in conjunction with ventriculomegaly. Other neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and vascular dementia share some overlapping clinical features. However, there is evidence that patients with comorbid NPH and Alzheimer's or Parkinson's disease may still exhibit good clinical response after CSF diversion. This study aims to evaluate clinical responses after ventriculo-peritoneal shunt (VPS) in a cohort of patients with coexisting NPH and neurodegenerative disease.

Methods

The study has two components; (i) a pilot study was performed that specifically focused upon patients with Complex NPH and following the inclusion of the Complex NPH subtype into consideration for the clinical NPH programme, (ii) a retrospective snapshot study was performed to confirm and characterize differences between Classic and Complex NPH patients being seen consecutively over the course of 1 year within a working subspecialist NPH clinic. We studied the characteristics of patients with Complex NPH, utilizing clinical risk stratification and multimodal biomarkers.

Results

There was no significant difference between responders and non-responders to CSF diversion on comorbidity scales. After VPS insertion, significantly more Classic NPH patients had improved cognition compared to Complex NPH patients (p = 0.005). Improvement in gait and urinary symptoms did not differ between the groups. 26% of the Classic NPH group showed global improvement of the triad, and 42% improved in two domains. Although only 8% showed global improvement of the triad, all Complex NPH patients improved in gait.

Conclusions

Our study has demonstrated that the presence of neurodegenerative disorders co-existing with NPH should not be the sole barrier to the consideration of high-volume tap test or lumbar drainage via a specialist NPH programme. Further characterization of distinct cohorts of NPH with differing degrees of CSF responsiveness due to overlay from neurodegenerative or comorbidity risk burden may aid toward more precise prognostication and treatment strategies. We propose a simplistic conceptual framework to describe NPH by its Classic vs. Complex subtypes to promote the clinical paradigm shift toward subspecialist geriatric neurosurgery by addressing needs for rapid screening tools at the clinical-research interface.

Utility of quantitative susceptibility mapping and diffusion kurtosis imaging in the diagnosis of early Parkinson's disease

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Putamen susceptibility value was higher in PD than controls one year into diagnosis.

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Putamen susceptibility value was associated with clinical motor scores in early PD.

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Mean diffusivity revealed greater cellular loss in the lateral substantial nigra.

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Putamen and caudate microstructural degradation were driven by radial diffusivity.

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A composite putamen-caudate DKI-QSM marker classified early PD from controls.

Objective

To investigate the utility of quantitative susceptibility mapping (QSM) and diffusion kurtosis imaging (DKI) as complementary tools in characterizing pathological changes in the deep grey nuclei in early Parkinson’s disease (PD) and their clinical correlates to aid in diagnosis of PD.

Method

Patients with a diagnosis of PD made within a year and age-matched healthy controls were recruited. All participants underwent clinical evaluation using the Unified Parkinson’s Disease Rating Scale (MDS-UPDRS III) and Hoehn & Yahr stage (H&Y), and brain 3 T MRI including QSM and DKI. Regions-of-interest (ROIs) in the caudate nucleus, putamen, globus pallidus, and medial and lateral substantia nigra (SN) were manually drawn to compare the mean susceptibility (representing iron deposition) and DKI indices (representing restricted water diffusion) between PD patients and healthy controls and in correlation with MDS-UPDRS III and H&Y, focusing on susceptibility value, mean diffusivity (MD) and mean kurtosis (MK).

Results

There were forty-seven PD patients (aged 68.7 years, 51% male, disease duration 0.78 years) and 16 healthy controls (aged 67.4 years, 63% male). Susceptibility value was increased in PD in all ROIs except the caudate, and was significantly different after multiple comparison correction in the putamen (PD: 64.75 ppb, HC: 44.61 ppb, p = 0.004). MD was significantly higher in PD in the lateral SN, putamen and caudate, the regions with the lowest susceptibility value. In PD patients, we found significant association between the MDS-UPDRS III score and susceptibility value in the putamen after correcting for age and sex (β = 0.21, p = 0.003). A composite DKI-QSM diagnostic marker based on these findings successfully differentiated the groups (p < 0.0001) and had “good” classification performance (AUC = 0.88).

Conclusions

QSM and DKI are complementary tools allowing a better understanding of the complex contribution of iron deposition and microstructural changes in the pathophysiology of PD.

Clinical correlates of white matter lesions in Parkinson's disease using automated multi-modal segmentation measures

BACKGROUND

Age-related white matter lesions (WML) are common, impact neuronal connectivity, and affect motor function and cognition. In addition to pathological nigrostriatal losses, WML are also common co-morbidities in Parkinson's disease (PD) that affect postural stability and gait. Automated brain volume measures are increasingly incorporated into the clinical reporting workflow to facilitate precision in medicine. Recently, multi-modal segmentation algorithms have been developed to overcome challenges with WML quantification based on single-modality input.

OBJECTIVE

We evaluated WML volumes and their distribution in a case-control cohort of PD patients to predict the domain-specific clinical severity using a fully automated multi-modal segmentation algorithm.

METHODS

Fifty-five subjects comprising of twenty PD patients and thirty-five age- and gender-matched control subjects underwent standardized motor/gait and cognitive assessments and brain MRI. Spatially differentiated WML obtained using automated segmentation algorithms on multi-modal MPRAGE and FLAIR images were used to predict domain-specific clinical severity. Preliminary statistical analysis focused on describing the relationship between WML and clinical scores, and the distribution of WML by brain regions. Subsequent stepwise regressions were performed to predict each clinical score using WML volumes in different brain regions, while controlling for age.

RESULTS

WML volume strongly correlates with both motor and cognitive dysfunctions in PD patients (p < 0.05), with differential impact in the frontal lobe and periventricular regions on cognitive domains (p < 0.01) and severity of motor deficits (p < 0.01), respectively.

CONCLUSION

Automated multi-modal segmentation algorithms may facilitate precision medicine through regional WML load quantification, which show potential as imaging biomarkers for predicting domain-specific disease severity in PD.

The splenial angle: a novel radiological index for idiopathic normal pressure hydrocephalus

Objectives

To evaluate the utility of the splenial angle (SA), an axial angular index of lateral ventriculomegaly measured on diffusion tensor MRI color fractional anisotropy maps, in differentiating NPH from Alzheimer’s disease (AD), Parkinson’s disease (PD), and healthy controls (HC), and post-shunt changes in NPH, compared to Evans’ index and callosal angle.

Methods

Evans’ index, callosal angle, and SA were measured on brain MRI of 76 subjects comprising equal numbers of age- and sex-matched subjects from each cohort of NPH, AD, PD, and HC by two raters. Receiver operating characteristics (ROC) and multivariable analysis were used to assess the screening performance of each measure in differentiating and predicting NPH from non-NPH groups respectively. Temporal changes in the measures on 1-year follow-up MRI in 11 NPH patients (with or without ventriculoperitoneal shunting) were also assessed.

Results

Inter-rater and intra-rater reliability were excellent for all measurements (intraclass correlation coefficients > 0.9). Pairwise comparison showed that SA was statistically different between NPH and AD/PD/HC subjects (p < 0.0001). SA performed the best in predicting NPH, with an area under the ROC curve of > 0.98, and was the only measure left in the final model of the multivariable analysis. Significant (p < 0.01) change in SA was seen at follow-up MRI of NPH patients who were shunted compared to those who were not.

Conclusions

The SA is readily measured on axial DTI color FA maps compared to the callosal angle and shows superior performance differentiating NPH from neurodegenerative disorders and sensitivity to ventricular changes in NPH after surgical intervention.

Key Points

• The splenial angle is a novel simple angular radiological index proposed for idiopathic normal pressure hydrocephalus, measured in the ubiquitous axial plane on DTI color fractional anisotropy maps.

• The splenial angle quantitates the compression and stretching of the posterior callosal commissural fibers alongside the distended lateral ventricles in idiopathic normal pressure hydrocephalus (NPH) using tools readily accessible in clinical practice and shows excellent test-retest reliability.

• Splenial angle outperforms Evans’ index and callosal angle in predicting NPH from healthy, Parkinson’s disease, and Alzheimer’s disease subjects on ROC analysis with an area under the curve of > 0.98 and is sensitive to morphological ventricular changes in NPH patients after ventricular shunting.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-07871-4.

Symbiotic bacteria attenuate Drosophila oviposition repellence to alkaline through acidification

Metazoans harbor a wealth of symbionts that are ever-changing the environment by taking up resources and/or excreting metabolites. One such common environmental modification is a change in pH. Conventional wisdom holds that symbionts facilitate the survival and production of their hosts in the wild, but this notion lacks empirical evidence. Here, we report that symbiotic bacteria in the genus Enterococcus attenuate the oviposition avoidance of alkaline environments in Drosophila. We studied the effects of alkalinity on oviposition preference for the first time, and found that flies are robustly disinclined to oviposit on alkali-containing substrates. This innate repulsion to alkaline environments is explained, in part, by the fact that alkalinity compromises the health and lifespan of both offspring and parent Drosophila. Enterococcus dramatically diminished or even completely reversed the ovipositional avoidance of alkalinity in Drosophila. Mechanistically, Enterococcus generate abundant lactate during fermentation, which neutralizes the residual alkali in an egg-laying substrate. In conclusion, Enterococcus protects Drosophila from alkali stress by acidifying the ovipositional substrate, and ultimately improves the fitness of the Drosophila population. Our results demonstrate that symbionts are profound factors in the Drosophila ovipositional decision, and extend our understanding of the intimate interactions between Drosophila and their symbionts.

Oxidized nicotinamide adenine dinucleotide-dependent mitochondrial deacetylase sirtuin-3 as a potential therapeutic target of Parkinson's disease

Mitochondrial impairment is associated with progressive dopamine (DA) neuron degeneration in Parkinson's disease (PD). Recent findings highlight that Sirtuin-3 (SIRT3), a mitochondrial protein, is an oxidized nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase and a key modulator in maintaining integrity and functions of mitochondria. SIRT3 plays vital roles in regulation of mitochondrial functions, including mitochondrial ATP generation and energy metabolism, anti-oxidant defense, and cell death and proliferation. SIRT3 can deacetylate the transcriptional factors and crosstalk with different signaling pathways to cooperatively modulate mitochondrial functions and regulate defensive mitochondrial quality control (QC) systems. Down-regulated NAD+ level and decreased SIRT3 activity are related to aging process and has been pathologically linked to PD pathogenesis. Further, SIRT3 can bind and deacetylate PTEN-induced kinase 1 (PINK1) and PD protein 2 E3 ubiquitin protein ligase (Parkin) to facilitate mitophagy. Leucine Rich Repeat Kinase 2 (LRRK2)-G2019S mutation in PD is linked to SIRT3 impairment. Furthermore, SIRT3 is inversely associated with α-synuclein aggregation and DA neuron degeneration in PD. SIRT3 chemical activators and NAD+ precursors can up-regulate SIRT3 activity to protect against DA neuron degeneration in PD models. Taken together, SIRT3 is a promising PD therapeutic target and studies of SIRT3 functional modulators with neuroprotective capability will be of clinical interest.

Evaluation of trigeminal nerve tractography using two-fold-accelerated simultaneous multi-slice readout-segmented echo planar diffusion tensor imaging

OBJECTIVES

Simultaneous multi-slice (SMS) imaging with short repetition time (TR) accelerates diffusion tensor imaging (DTI) acquisitions. However, its impact when combined with readout-segmented echo planar imaging (RESOLVE) on the cranial nerves given the challenging skull base/posterior fossa terrain is unexplored. We evaluated the reliability of trigeminal nerve DTI metrics using SMS with RESOLVE-DTI.

METHODS

Eight healthy controls and six patients with unilateral trigeminal neuralgia (TN) underwent brain MRI scan. Three different RESOLVE-DTI protocols were performed on a 3-T MRI system: non-SMS (TR = 4330 ms), SMS with identical TR (4330 ms), and SMS with short TR (2400 ms). Pontine signal-to-noise ratio (SNR) and DTI metrics of the trigeminal nerve streamlines tracked by two independent raters using deterministic tractography and standardized tracking protocol were obtained. These were statistically analyzed and compared across the three protocols using intra-rater and inter-rater intraclass correlation coefficients (ICCs), one-way analysis of variance (ANOVA), post hoc analysis, and linear regression.

RESULTS

On visual screening, there were no artifacts across the trigeminal nerves. All data also cleared objective image quality assurance analysis. Pontine SNR was similar for the two SMS protocols and higher for the non-SMS RESOLVE-DTI (F_(2,36) = 4.40, p = 0.02). Intra-rater and inter-rater ICCs were very good (> 0.85). Trigeminal nerve DTI metrics were consistently measured by the three protocols, revealing significant linear relationships between non-SMS- and SMS-derived DTI metrics.

CONCLUSION

SMS RESOLVE-DTI enables fast and reliable evaluation of microstructural integrity of the trigeminal nerve, with potential application in the clinical management of TN.

KEY POINTS

• Readout-segmented diffusion-weighted echo planar imaging (RESOLVE-DTI) reduces image distortion artifacts in the posterior fossa but its long acquisition time limits clinical utility. • Simultaneous multi-slice (SMS) imaging combined with RESOLVE-DTI provides reliable trigeminal nerve tractography with potential applications in trigeminal neuralgia. • Two-fold-accelerated RESOLVE-DTI yields comparable trigeminal nerve streamlines and DTI metrics while near-halving acquisition time.

Dopamine transporter neuroimaging accurately assesses the maturation of dopamine neurons in a preclinical model of Parkinson's disease

BACKGROUND

Significant developments in stem cell therapy for Parkinson's disease (PD) have already been achieved; however, methods for reliable assessment of dopamine neuron maturation in vivo are lacking. Establishing the efficacy of new cellular therapies using non-invasive methodologies will be critical for future regulatory approval and application. The current study examines the utility of neuroimaging to characterise the in vivo maturation, innervation and functional dopamine release of transplanted human embryonic stem cell-derived midbrain dopaminergic neurons (hESC-mDAs) in a preclinical model of PD.

METHODS

Female NIH RNu rats received a unilateral stereotaxic injection of 6-OHDA into the left medial forebrain bundle to create the PD lesion. hESC-mDA cell and sham transplantations were carried out 1 month post-lesion, with treated animals receiving approximately 4 × 10⁵ cells per transplantation. Behavioural analysis, [¹⁸F]FBCTT and [¹⁸F]fallypride microPET/CT, was conducted at 1, 3 and 6 months post-transplantation and compared with histological characterisation at 6 months.

RESULTS

PET imaging revealed transplant survival and maturation into functional dopaminergic neurons. [¹⁸F]FBCTT-PET/CT dopamine transporter (DAT) imaging demonstrated pre-synaptic restoration and [¹⁸F]fallypride-PET/CT indicated functional dopamine release, whilst amphetamine-induced rotation showed significant behavioural recovery. Moreover, histology revealed that the grafted cells matured differently in vivo producing high- and low-tyrosine hydroxylase (TH) expressing cohorts, and only [¹⁸F]FBCTT uptake was well correlated with differentiation.

CONCLUSIONS

This study provides further evidence for the value of in vivo functional imaging for the assessment of cell therapies and highlights the utility of DAT imaging for the determination of early post-transplant cell maturation and differentiation of hESC-mDAs.

Parkinson's disease: etiopathogenesis and treatment

The concept of 'idiopathic' Parkinson's disease (PD) as a single entity has been challenged with the identification of several clinical subtypes, pathogenic genes and putative causative environmental agents. In addition to classic motor symptoms, non-motor manifestations (such as rapid eye movement sleep disorder, anosmia, constipation and depression) appear at prodromic/premotor stage and evolve, along with cognitive impairment and dysautonomia, as the disease progresses, often dominating the advanced stages of the disease. The key molecular pathogenic mechanisms include α-synuclein misfolding and aggregation, mitochondrial dysfunction, impairment of protein clearance (associated with deficient ubiquitin-proteasome and autophagy-lysosomal systems), neuroinflammation and oxidative stress. The involvement of dopaminergic as well as noradrenergic, glutamatergic, serotonergic and adenosine pathways provide insights into the rich and variable clinical phenomenology associated with PD and the possibility of alternative therapeutic approaches beyond traditional dopamine replacement therapies.One of the biggest challenges in the development of potential neuroprotective therapies has been the lack of reliable and sensitive biomarkers of progression. Immunotherapies such as the use of vaccination or monoclonal antibodies directed against aggregated, toxic α-synuclein.as well as anti-aggregation or protein clearance strategies are currently investigated in clinical trials. The application of glucagon-like peptide one receptor agonists, specific PD gene target agents (such as GBA or LRRK2 modifiers) and other potential disease modifying drugs provide cautious optimism that more effective therapies are on the horizon. Emerging therapies, such as new symptomatic drugs, innovative drug delivery systems and novel surgical interventions give hope to patients with PD about their future outcomes and prognosis.

Nonsteroidal Anti-inflammatory Use and LRRK2 Parkinson's Disease Penetrance

BACKGROUND

The penetrance of leucine rich repeat kinase 2 (LRRK2) mutations is incomplete and may be influenced by environmental and/or other genetic factors. Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to reduce inflammation and may lower Parkinson's disease (PD) risk, but their role in LRRK2-associated PD is unknown.

OBJECTIVES

The objective of this study is to evaluate the association of regular NSAID use and LRRK2-associated PD.

METHODS

Symptomatic ("LRRK2-PD") and asymptomatic ("LRRK2-non-PD") participants with LRRK2 G2019S, R1441X, or I2020T variants (definitely pathogenic variant carriers) or G2385R or R1628P variants (risk variant carriers) from 2 international cohorts provided information on regular ibuprofen and/or aspirin use (≥2 pills/week for ≥6 months) prior to the index date (diagnosis date for PD, interview date for non-PD). Multivariate logistic regression was used to evaluate the relationship between regular NSAID use and PD for any NSAID, separately for ibuprofen and aspirin in all carriers and separately in pathogenic and risk variant groups.

RESULTS

A total of 259 LRRK2-PD and 318 LRRK2-non-PD participants were enrolled. Regular NSAID use was associated with reduced odds of PD in the overall cohort (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.21-0.57) and in both pathogenic and risk variant carriers (OR_Pathogenic , 0.38; 95% CI, 0.21-0.67 and OR_RiskVariant , 0.19; 95% CI, 0.04-0.99). Similar associations were observed for ibuprofen and aspirin separately (OR_Ibuprofen , 0.19; 95% CI, 0.07-0.50 and OR_Aspirin , 0.51; 95% CI, 0.28-0.91).

CONCLUSIONS

Regular NSAID use may be associated with reduced penetrance in LRRK2-associated PD. The LRRK2 protein is involved in inflammatory pathways and appears to be modulated by regular anti-inflammatory use. Longitudinal observational and interventional studies of NSAID exposure and LRRK2-PD are needed to confirm this association. © 2020 International Parkinson and Movement Disorder Society.

Potassium channel dysfunction in human neuronal models of Angelman syndrome

Disruptions in the ubiquitin protein ligase E3A (UBE3A) gene cause Angelman syndrome (AS). Whereas AS model mice have associated synaptic dysfunction and altered plasticity with abnormal behavior, whether similar or other mechanisms contribute to network hyperactivity and epilepsy susceptibility in AS patients remains unclear. Using human neurons and brain organoids, we demonstrate that UBE3A suppresses neuronal hyperexcitability via ubiquitin-mediated degradation of calcium- and voltage-dependent big potassium (BK) channels. We provide evidence that augmented BK channel activity manifests as increased intrinsic excitability in individual neurons and subsequent network synchronization. BK antagonists normalized neuronal excitability in both human and mouse neurons and ameliorated seizure susceptibility in an AS mouse model. Our findings suggest that BK channelopathy underlies epilepsy in AS and support the use of human cells to model human developmental diseases.

The precarious use of charm needles susuk in treatment of low back pain by traditional medicine practitioners and its possible risk to patient safety

A 68-year-old female presented with a 1-month history of lower back pain with right-sided radiculopathy and numbness. She was diagnosed with lumbar spondylosis and treated conservatively with analgesia and physiotherapy. Imaging showed multiple susuk, a metal alloy, in the lower back region and other regions of the body. The patient had undergone traditional medicine consultation 10 years earlier when the susuk was inserted in the lower back as talisman. The practice of the insertion of susuk is popular in rural East Malaysia and Indonesia. These foreign bodies act as possible causes of chronic inflammation and granuloma formation. In addition, the localised heighten peril upon imaging. This report suggests that the insertion of multiple susuk as talisman carries risk to safety of patients when imaging, and this practice complicates the management of musculoskeletal disorders.

Increased Activation of Default Mode Network in Early Parkinson's With Excessive Daytime Sleepiness

Background and Objectives

The underlying neuropathology of excessive daytime sleepiness (EDS) remains elusive in Parkinson's disease (PD). We aim to investigate neural network changes that underlie EDS in PD.

Methods

Early PD patients comprising eighty-one patients without EDS (EDS-) and seventeen patients with EDS (EDS+) received a resting state functional MRI scan and the Epworth Sleepiness Scale (ESS). Connectivities within the default mode network (DMN), motor and basal ganglia networks were compared between the EDS+ and EDS- groups. Correlations between network connectivity and the severity of EDS were investigated through linear regression.

Results

EDS+ patients displayed a trend of increased network connectivity of the posterior DMN (pDMN). A significant positive correlation was found between connectivity of the ventromedial prefrontal cortex in the pDMN and ESS.

Conclusion

EDS+ patients are likely to display increased activation in the DMN, suggesting neural compensation in early PD or impaired attentiveness due to mechanisms such as mind-wandering.

The Therapeutic Implications of Tea Polyphenols Against Dopamine (DA) Neuron Degeneration in Parkinson's Disease (PD)

: Accumulative evidence indicated that the pathologically accumulated metal ions (iron species and Mn³⁺) and abnormally up-regulated monoamine oxidase B (MAOB) activity induced oxidation of endogenous dopamine (DA) can lead to mitochondria impairment, lysosome dysfunction, proteasome inhibition, and selective DA neuron vulnerability, which is implicated in the pathogenesis of Parkinson's disease (PD). The DA oxidation can generate deleterious reactive oxygen species (ROS) and highly reactive DA quinones (DAQ) to induce DA-related toxicity, which can be alleviated by DA oxidation suppressors, ROS scavengers, DAQ quenchers, and MAOB inhibitors. On the other hand, the nuclear factor erythroid 2-related factor 2 (Nrf2)-Keap1 and Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) anti-oxidative and proliferative signaling pathways play roles in anti-oxidative cell defense and mitochondria biogenesis, which is implicated in DA neuron protections. Therefore, agents with capabilities to suppress DA-related toxicity including inhibition of DA oxidation, scavenge of ROS, detoxification of DAQ, inhibition of MAOB, and modulations of anti-oxidative signaling pathways can be protective to DA neurons. Accumulative evidence shows that tea or coffee consumptions and smoking are related to deceased PD prevalence with unknown mechanisms. In this study, we investigate the protective capabilities of tea polyphenols and other PD relevant agents to inhibit DA-related toxicity and protect against environmental or genetic factors induced DA neuron degeneration in vitro and in vivo. We find that tea polyphenols can significantly suppress DA-related toxicity to protect DA neurons. The tea polyphenols can protect DA neurons via inhibition of DA oxidation, conjugation with DAQ, scavenge of ROS, inhibition of MAOB, and modulations of Nrf2-Keap1 and PGC-1α anti-oxidative signaling pathways. The tea polyphenols with more phenolic hydroxyl groups and ring structures have stronger protective functions. The protective capabilities of tea polyphenols is further strengthened by evidence that phenolic hydroxyl groups can directly conjugate with DAQ. However, GSH and other sulfhydyl groups containing agents have weaker capabilities to abrogate DA oxidation, detoxify ROS and DAQ and inhibit MAOB; whereas nicotine (NICO) and caffeine (CAF) can only modulate Nrf2-Keap1 and PGC-1α pathways to protect DA neurons weakly. The tea polyphenols are identified to protect against overexpression of mutant A30P α-synuclein (α-syn) induced DA neuron degeneration and PD-like symptoms in transgenic Drosophila. Based on achievements from current studies, the excellent and versatile protective capabilities of tea polyphenols are highlighted, which will contribute and benefit to future anti-PD therapy.

Differentiating Parkinson's disease motor subtypes using automated volume-based morphometry incorporating white matter and deep gray nuclear lesion load

Background

Periventricular leukoaraiosis may be an important pathological change in postural instability gait disorder (PIGD), a motor subtype of Parkinson's disease (PD). Clinical diagnosis of PIGD may be challenging for the general neurologist.

Purpose

To evaluate 1) the utility of a fully automated volume‐based morphometry (Vol‐BM) in characterizing imaging diagnostic markers in PD and PIGD, including, 2) novel deep gray nuclear lesion load (GMab), and 3) discriminatory performance of a Vol‐BM model construct in classifying the PIGD subtype.

Study Type

Prospective.

Subjects

In all, 23 PIGD, 21 PD, and 20 age‐matched healthy controls (HC) underwent MRI brain scans and clinical assessments.

Field Strength/Sequence

3.0T, sagittal 3D‐magnetization‐prepared rapid gradient echo (MPRAGE), and fluid‐attenuated inversion recovery imaging (FLAIR) sequences.

Assessment

Clinical assessment was conducted by a movement disorder neurologist. The MR brain images were then segmented using an automated multimodal Vol‐BM algorithm (MorphoBox) and reviewed by two authors independently.

Statistical Testing

Brain segmentation and clinical parameter differences and dependence were assessed using analysis of variance (ANOVA) and regression analysis, respectively. Logistic regression was performed to differentiate PIGD from PD, and discriminative reliability was evaluated using receiver operating characteristic (ROC) analysis.

Results

Significantly higher white matter lesion load (WMab) (P < 0.01), caudate GMab (P < 0.05), and lateral and third ventricular (P < 0.05) volumetry were found in PIGD, compared with PD and HC. WMab, caudate and putamen GMab, and caudate, lateral, and third ventricular volumetry showed significant coefficients (P < 0.005) in linear regressions with balance and gait assessments in both patient groups. A model incorporating WMab, caudate GMab, and caudate GM discriminated PIGD from PD and HC with a sensitivity = 0.83 and specificity = 0.76 (AUC = 0.84).

Data Conclusion

Fast, unbiased quantification of microstructural brain changes in PD and PIGD is feasible using automated Vol‐BM. Composite lesion load in the white matter and caudate, and caudate volumetry discriminated PIGD from PD and HC, and showed potential in classification of these disorders using supervised machine learning.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. Magn. Reson. Imaging 2020;51:748–756.

The Characteristics of Patients Associated With High Caregiver Burden in Parkinson's Disease in Singapore

Introduction: Given the complex multitude of Parkinson's disease (PD) symptoms, caregiving for PD patients can be highly demanding. Our study was aimed to investigate the characteristics of PD patients related to different levels of caregiver burden.

Methods: This cross-sectional study recruited 104 idiopathic PD patient-caregiver pairs. Patients were evaluated on motor, non-motor symptoms, and quality of life (QoL). Caregiver burden was quantified using Zarit Burden Inventory and subsequently stratified into 3 subgroups. Statistical analysis was performed to identify differences in the no-or little, mild-moderate, and high caregiver burden subgroups.

Results: The mean disease duration was significantly longer in the high caregiver burden group compared to no-or little group (9.63 vs. 5.17 years; p-value 0.003). The mean levodopa equivalent daily dose (LEDD) and mean total UPDRS Part IV scores (UPDRS4) were significantly higher in the high caregiver burden group compared to no-or little group (p-value 0.011 and 0.004, respectively). The high caregiver burden group had significantly higher median QoL scores (PDQ-39) for PD patients for domain 2 (ADL, p-value 0.005), domain 4 (stigma, p-value 0.005), and domain 6 (cognition, p-value 0.002) compared to no-or little group.

Conclusion: Greater caregiver burden was observed in PD patients with more prolonged disease duration, higher LEDD to control motor symptoms as well as greater levodopa related motor complications. Further studies on potential interventions to mitigate or delay levodopa related motor complications may reduce caregiver burden. Marked worsening in patient's QoL, specifically ADL, stigma and cognition in the high compared to no-or little caregiver burden group suggests the possible utility of monitoring these factors for early identification of increasing caregiver stress and burden.

In utero infection of Zika virus leads to abnormal central nervous system development in mice

The World Health Organization has declared ZIKA virus (ZIKV) a global public health emergency, prompted by the association of ZIKV infections with severe brain abnormalities in the human fetus. ZIKV preferentially targets human neuronal precursor cells (NPCs) in both monolayer and cortical brain organoid culture systems and stunts their growth. Although ZIKV is well recognized to cause microcephaly, there is no systematic analysis to demonstrate the effect of ZIKV on central nervous system (CNS) development, including brain malformations and spinal cord dysfunction. Here, we conducted a longitudinal analysis to show that a novel mouse model (infected in utero and monitored after birth until adulthood) recapitulates the effects of ZIKV infection affecting neural stem cells fate and leads to a thinner cortex and a smaller brain. Furthermore, we demonstrate the effect of ZIKV on spinal cord function. Specifically, we found significant reductions in neuron numbers in the anterior horn of grey matter of the spinal cord and muscle dystrophy with a significant decrease in forepaw grip strength in the ZIKV group. Thus, the established mouse model of ZIKV infection leading to abnormal CNS development will help to further advance our understanding of the disease pathogenesis.

Periventricular White Matter Abnormalities on Diffusion Tensor Imaging of Postural Instability Gait Disorder Parkinsonism

BACKGROUND AND PURPOSE

Postural instability gait disorder is a motor subtype of Parkinson disease associated with predominant gait dysfunction. We investigated the periventricular white matter comprising longitudinal, thalamic, and callosal fibers using diffusion tensor MR Imaging and examined clinical correlates in a cohort of patients with Parkinson disease and postural instability gait disorder and healthy controls.

MATERIALS AND METHODS

All subjects underwent the Tinetti Gait and Balance Assessment and brain MR imaging. The DTI indices (fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity) from ROIs dropped over the superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, anterior thalamic radiation, anterior and posterior limbs of the internal capsule, and the genu and body of corpus callosum were evaluated.

RESULTS

Our findings showed that the superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, anterior thalamic radiation, genu of the corpus callosum, and body of the corpus callosum are more affected in postural instability gait disorder than in those with Parkinson disease or healthy controls, with more group differences among the longitudinal fibers. Only the callosal fibers differentiated the postural instability gait disorder and Parkinson disease groups. DTI measures in the superior longitudinal fasciculus, frontostriatal fibers (anterior thalamic radiation, anterior limb of the internal capsule), and genu of the corpus callosum fibers correlated with clinical gait severity.

CONCLUSIONS

Findings from this case-control cohort lend further evidence to the role of extranigral pathology and, specifically, the periventricular fibers in the pathophysiology of postural instability gait disorder.

Amyloid-β and Parkinson's disease

Parkinson's disease (PD) is the second commonest neurodegenerative disorder in the world with a rising prevalence. The pathophysiology is multifactorial but aggregation of misfolded α-synuclein is considered to be a key underpinning mechanism. Amyloid-β (Aβ) and tau deposition are also comorbid associations and especially Aβ deposition is associated with cognitive decline in PD. Some existing evidence suggests that low cerebrospinal fluid (CSF) Aβ₄₂ is predictive of future cognitive impairment in PD. Recent studies also show that CSF Aβ is associated with the postural instability and gait difficulties (PIGD) or the newly proposed cholinergic subtype of PD, a possible risk factor for cognitive decline in PD. The glial-lymphatic system, responsible for convective solute clearance driven by active fluid transport through aquaporin-4 water channels, may be implicated in brain amyloid deposition. A better understanding of the role of this system and more specifically the role of Aβ in PD symptomatology, could introduce new treatment and repurposing drug-based strategies. For instance, apomorphine infusion has been shown to promote the degradation of Aβ in rodent models. This is further supported in a post-mortem study in PD patients although clinical implications are unclear. In this review, we address the clinical implication of cerebral Aβ deposition in PD and elaborate on its metabolism, its role in cognition and motor function/gait, and finally assess the potential effect of apomorphine on Aβ deposition in PD.

Pathophysiological mechanisms linking F-box only protein 7 (FBXO7) and Parkinson's disease (PD)

Mutations of F-box only protein 7 (FBXO7) gene are associated with a severe form of autosomal recessive juvenile Parkinson's disease (PD) (PARK15) with clinical features of Parkinsonian-Pyramidal syndrome (PPS). FBXO7 is an adaptor protein in SCF^FBXO7 ubiquitin E3 ligase complex that recognizes and mediates degradative or non-degradative ubiquitination of substrates. The FBXO7 protein can regulate cell cycle, proliferation, mitochondrial and proteasome functions via interactions with multiple target proteins. Five PARK15-linked FBXO7 gene mutations and several PD-associated single nucleotide polymorphisms (SNP) have been identified so far. WT FBXO7 proteins possess dual protective and deleterious functions, whereas PARK15-linked FBXO7 mutants are toxic. FBXO7 is a stress response protein and stress challenges can promote translocation of FBXO7 protein from nucleus into mitochondria and even form deleterious protein aggregate in mitochondria. FBXO7 mutants aggravate protein aggregation in mitochondria and inhibit mitophagy. The pathological mechanisms concerning FBXO7-relevant protein aggregation, mitochondria impairment, reactive oxygen species (ROS) generation and mitophagy modulation in PARK15 pathogenesis are highlighted and discussed in the current review.

Liver Transplant Waitlist Outcomes and the Allocation of Hepatocellular Carcinoma Model for End-Stage Liver Disease Exception Points at a Low-Volume Center

BACKGROUND

Organ scarcity continues to be the main problem limiting the number of liver transplants performed. Outcomes of patients waitlisted for an organ in an Asian country with low organ donation rate have not been well evaluated. Our current policy of allocating 15 exception points to patients with hepatocellular carcinoma (HCC) to render them competitive for a transplant also requires review.

METHODS

The waiting list registry and the organ transplant registry of a single institution in Asia were reviewed from December 2005 to June 2016 for all patients who underwent liver transplantation. Patient characteristics and outcomes of waitlist dropouts were evaluated. Statistical analyses were performed using SPSS version 20.0.

RESULTS

One hundred seventy-three patients were waitlisted for a deceased donor liver-only transplant. The most common etiology of liver disease was hepatitis B, followed by cholestatic diseases. Approximately half of the patients had HCC (45.6%). Priority listing for transplant comprised 15.6% of cases. Median Model for End-Stage Liver Disease (MELD) at listing was 15, and median waiting time to transplant was 17 weeks (interquartile range = 6.5-43.5). Overall, 89 (51.4%) patients underwent liver transplantation and 68 (39.3%) dropped out. For patients with HCC, the most common cause of dropout was progression beyond University of California San Francisco transplant criteria (62.5%). The cumulative incidence of dropout at 3 months among patients with HCC who received exception MELD scores was 11%. This was higher than those listed with physiologic MELD of 14-16 points (7%) but lower than those with 17-19 points (16%).

CONCLUSIONS

Hepatitis B-related liver disease and HCC comprise the majority of patients listed for liver transplant. Dropout rates are high and this is due to the lack of donor organs. The current policy of allocating 15 exception MELD points to patients with HCC within transplant criteria may underestimate the dropout risk of patients with HCC in our population.

Modelling Alzheimer's disease: Insights from in vivo to in vitro three-dimensional culture platforms

Alzheimer's disease (AD) is the most common form of dementia and is characterized by progressive memory loss, impairment of other cognitive functions, and inability to perform activities of daily life. The key to understanding AD aetiology lies in the development of effective disease models, which should ideally recapitulate all aspects pertaining to the disease. A plethora of techniques including in vivo, in vitro, and in silico platforms have been utilized in developing disease models of AD over the years. Each of these approaches has revealed certain essential characteristics of AD; however, none have managed to fully mimic the pathological hallmarks observed in the AD human brain. In this review, we will provide details into the genesis, evolution, and significance of the principal methods currently employed in modelling AD, the advantages and limitations faced in their application, including the headways made by each approach. This review will focus primarily on two-dimensional and three-dimensional in vitro modelling of AD, which during the last few years has made significant breakthroughs in the areas of AD pathology and therapeutic screening. In addition, a glimpse into state-of-the-art neural tissue engineering techniques incorporating biomaterials and microfluidics technologies is provided, which could pave the way for the development of more accurate and comprehensive AD models in the future.

Targeted exome sequencing reveals homozygous TREM2 R47C mutation presenting with behavioral variant frontotemporal dementia without bone involvement

To identify genes associated with frontotemporal dementia (FTD) in South-East Asia, targeted exome sequencing and C9orf72 genotyping was performed in 198 subjects (52 patients with FTD and 146 healthy controls) who were screened for mutations in 12 FTD-associated genes. We detected a homozygous TREM2 R47C mutation in a patient with behavioral variant FTD without bone cysts or bone-associated phenotype. Two novel nonsense GRN mutations in 3 FTD patients from the Philippines were detected, but no known pathogenic mutations in other FTD-associated genes were found. In 45 subjects screened for C9orf72 repeat expansions, no pathogenic expansion (≥30 repeats) was identified, but there was a higher proportion of intermediate length (≥10-29 repeats) alleles in patients compared with controls (8/90 alleles, 8.9% vs. 9/164 alleles, 5.5%). Overall, we detected a mutation rate of 7.7% (4/52 patients) in our cohort. Given recent findings of enrichment of rare TREM2 variants (including R47C) in Alzheimer's disease, it is notable that we detected a homozygous TREM2 R47C carrier presenting with an FTD rather than an Alzheimer's disease phenotype.

Differential White Matter Regional Alterations in Motor Subtypes of Early Drug-Naive Parkinson's Disease Patients

BACKGROUND

Parkinson's disease (PD) can be classified into tremor dominant (TD) and postural instability and gait difficulty (PIGD) subtypes with TD considered as the benign subtype. The neural alterations of the 2 subtypes in the early stages before administration of medications remain elusive.

OBJECTIVE

This study assessed the subtype-related white matter (WM) microstructural features in newly diagnosed and drug-naive PD patients from the Parkinson's Progression Markers Initiative (PPMI).

METHODS

Sixty-five early PDs with stable subtypes (52 TD and 13 PIGD patients) and 61 controls underwent diffusion tensor imaging (DTI) scanning and clinical assessment. Tract-based special statistics (TBSS), graph-theoretical and network-based analyses were used to compare WM regional and network features between groups.

RESULTS

No differences in disease stages and duration were found between the 2 patient groups. TD patients showed increased fractional anisotropy (FA), but decreased radial and axial diffusivities (RD and AD) in several projection, association, and commissural tracts, compared with PIGD patients and controls. Motor severity had mild-to-moderate correlations with FA and RD of the corpus callosum (genu) in TD, but strong correlations with FA and RD of multiple association tracts in PIGD. Conversely, no significant network changes were noted.

CONCLUSIONS

TD patients showed regionally increased FA but decreased diffusivities, implying neural reorganization to compensate PD pathology in early stages. PIGD patients, despite having similar disease stages and duration, exhibited more WM degradation. These results demonstrate differential WM regional features between the 2 subtypes in early PD and support the notion of TD being a benign subtype.

Depression, anxiety, and apathy in Parkinson's disease: insights from neuroimaging studies

Depression, anxiety and apathy are common mood disturbances in Parkinson's disease (PD) but their pathophysiology is unclear. Advanced neuroimaging has been increasingly used to unravel neural substrates linked to these disturbances. A systematic review is provided of neuroimaging findings in depression, anxiety and apathy in PD. A PubMed, MEDLINE and EMBASE search of peer‐reviewed original research articles on these mood disturbances in PD identified 38 studies on depression, eight on anxiety and 14 on apathy in PD. Most of the imaging studies used either position emission tomography or single‐photon emission computed tomography techniques. These studies generally suggest increased neural activity in the prefrontal regions and decreased functional connectivity between the prefrontal−limbic networks in depressed patients. Functional imaging studies revealed an inverse correlation between dopaminergic density in the caudate and putamen with the severity of anxiety in PD. There was no consistent correlation between dopaminergic density of thalamus and anxiety. Studies demonstrated both positive and inverse correlations between apathy and metabolism or activity in the striatum, amygdalar, prefrontal, temporal and parietal regions. The clinical variability of study subjects and differences in image pre‐processing and analytical strategies may contribute to discrepant findings in these studies. Both nigrostriatal and extra‐nigrostriatal pathways (in particular the frontal region and its connecting areas) are affected in mood disorders in PD. Identifying the relative contributions of these neural pathways in PD patients with overlapping motor and mood symptoms could provide new pathophysiological clues for the development of better therapeutic targets for affected patients.

Mild cognitive impairment in Parkinson's disease: a distinct clinical entity?

BACKGROUND

Mild cognitive impairment in Parkinson's disease (PD-MCI) is a common clinical condition. Understanding its pathology and clinical features is important for early intervention before the onset of dementia. In the past, variable definitions and differences in neuropsychological batteries generated divergent results of the affected cognitive patterns.

MAIN BODY

The introduction of PD-MCI criteria by the Movement Disorders Society (MDS) Task Force provides a more uniform system for defining and measuring PD-MCI and may improve the validity of future research. PD-MCI is likely to be heterogeneous since it can coexist with Alzheimer's disease and/ or Lewy body pathologies in PD. Pathogeneses of neuropsychiatric disturbances, such as depression, anxiety and apathy, are associated with PD with or without MCI. In addition, cognitive reserve formed by patients' unique life experiences may influence the outward cognitive performance despite the presence of the aforementioned pathogeneses and hence alter the diagnosis of MCI.

CONCLUSION

The overlap of cognitive impairment across different neurodegenerative diseases suggests that PD-MCI is likely to result from a mixture of complex pathophysiologies, rather than being a distinct pathologic entity. Differentiating MCI from other organic symptoms in PD would facilitate novel therapeutic strategies.

Immature Midbrain Dopaminergic Neurons Derived from Floor-Plate Method Improve Cell Transplantation Therapy Efficacy for Parkinson's Disease

Recent reports have indicated human embryonic stem cells-derived midbrain dopamine (mDA) neurons as proper cell resources for use in Parkinson's disease (PD) therapy. Nevertheless, no detailed and systematic study has been conducted to identify which differentiation stages of mDA cells are most suitable for transplantation in PD therapy. Here, we transplanted three types of mDA cells, DA progenitors (differentiated in vitro for 16 days [D16]), immature DA neurons (D25), and DA neurons (D35), into PD mice and found that all three types of cells showed high viability and strong neuronal differentiation in vivo. Both D25 and D35 cells showed neuronal maturation and differentiation toward TH⁺ cells and, accordingly, satisfactory behavioral functional recovery. However, transplanted D16 cells were less capable of producing functional recovery. These findings provide a valuable guideline for standardizing the differentiation stage of the transplantable cells used in clinical cell therapy for PD. Stem Cells Translational Medicine 2017;6:1803-1814.

Generation of a human induced pluripotent stem cell (iPSC) line carrying the Parkinson's disease linked LRRK2 variant S1647T

Peripheral blood mononuclear cells (PBMCs) were collected from a clinically diagnosed 64-year old male Parkinson's disease (PD) patient with S1647T variant in the LRRK2 gene. The PMBCs were reprogrammed with the human OSKM transcription factors using the Sendai-virus reprogramming system. The transgene-free iPSC showed pluripotency confirmed by immunofluorescent staining for pluripotency markers and differentiated into the 3 germ layers in vivo. The iPSC line also showed normal karyotype. This cellular model will be useful for further function studies and therapeutic screening.

Derivation of human induced pluripotent stem cell (iPSC) line with LRRK2 gene R1398H variant in Parkinson's disease

Peripheral blood mononuclear cells (PBMCs) were collected from a clinically diagnosed 72-year old female Parkinson's disease (PD) patient with R1398H variant in the LRRK2 gene. The PMBCs were reprogrammed with the human OSKM transcription factors using the Sendai-virus reprogramming system. The transgene-free iPSC showed pluripotency confirmed by immunofluorescent staining for pluripotency markers and differentiated into the 3 germ layers in vivo. The iPSC line also showed normal karyotype. This cellular model provides a good platform for studying the mechanism of PD, and also for drug testing and gene therapy studies.