Tauopathies with parkinsonism: clinical spectrum, neuropathologic basis, biological markers, and treatment options

Tau protein modulates an epigenetic mechanism of cellular senescence in human SH-SY5Y neuroblastoma cells

Introduction: Progressive Tau deposition in neurofibrillary tangles and neuropil threads is the hallmark of tauopathies, a disorder group that includes Alzheimer's disease. Since Tau is a microtubule-associated protein, a prevalent concept to explain the pathogenesis of tauopathies is that abnormal Tau modification contributes to dissociation from microtubules, assembly into multimeric β-sheets, proteotoxicity, neuronal dysfunction and cell loss. Tau also localizes in the cell nucleus and evidence supports an emerging function of Tau in DNA stability and epigenetic modulation. Methods: To better characterize the possible role of Tau in regulation of chromatin compaction and subsequent gene expression, we performed a bioinformatics analysis of transcriptome data obtained from Tau-depleted human neuroblastoma cells. Results: Among the transcripts deregulated in a Tau-dependent manner, we found an enrichment of target genes for the polycomb repressive complex 2. We further describe decreased cellular amounts of the core components of the polycomb repressive complex 2 and lower histone 3 trimethylation in Tau deficient cells. Among the de-repressed polycomb repressive complex 2 target gene products, IGFBP3 protein was found to be linked to increased senescence induction in Tau-deficient cells. Discussion: Our findings propose a mechanism for Tau-dependent epigenetic modulation of cell senescence, a key event in pathologic aging.

Neurological update: the palliative care landscape for atypical parkinsonian syndromes

Atypical parkinsonian syndromes are neurodegenerative conditions, characterised by rapid disease progression and shorter life expectancy compared to idiopathic Parkinson's disease. These conditions inflict substantial physical and psychosocial burden on patients and their families; hence, there is a clear rationale for a palliative care approach from diagnosis. An interdisciplinary care model has been shown to improve symptom burden, quality of life and engagement with advance care planning, in a heterogeneous group of neurodegenerative conditions. In this update, we summarise how the landscape for treating these patients has changed and the questions that still need to be resolved.

α-Synuclein conformers reveal link to clinical heterogeneity of α-synucleinopathies

α-Synucleinopathies, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy, are a class of neurodegenerative diseases exhibiting intracellular inclusions of misfolded α-synuclein (αSyn), referred to as Lewy bodies or oligodendroglial cytoplasmic inclusions (Papp-Lantos bodies). Even though the specific cellular distribution of aggregated αSyn differs in PD and DLB patients, both groups show a significant pathological overlap, raising the discussion of whether PD and DLB are the same or different diseases. Besides clinical investigation, we will focus in addition on methodologies, such as protein seeding assays (real-time quaking-induced conversion), to discriminate between different types of α-synucleinopathies. This approach relies on the seeding conversion properties of misfolded αSyn, supporting the hypothesis that different conformers of misfolded αSyn may occur in different types of α-synucleinopathies. Understanding the pathological processes influencing the disease progression and phenotype, provoked by different αSyn conformers, will be important for a personalized medical treatment in future.

Elongator promotes neuritogenesis via regulation of tau stability through acly activity

The six subunits (Elp1 to Elp6) Elongator complex promotes specific uridine modifications in tRNA’s wobble site. Moreover, this complex has been indirectly involved in the regulation of α-tubulin acetylation in microtubules (MTs) via the stabilization of ATP-Citrate Lyase (Acly), the main cytosolic source of acetyl-CoA production in cells, a key substrate used for global protein acetylation. Here, we report additional evidence that Elongator activity is important for proper cytoskeleton remodeling as cells lacking expression of Elp1 show morphology impairment; including distinct neurite process formation and disorganization and instability of MTs. Here, we show that loss of Elongator results in a reduction of expression of the microtubule associated protein Tau (MAPT). Tau, is a well-known key MT regulator in neurons whose lysines can be competitively acetylated or ubiquitylated. Therefore, we tested whether Tau is an indirect acetylation target of Elongator. We found that a reduction of Elongator activity leads to a decrease of lysine acetylation on Tau that favors its proteasomal degradation. This phenotype was prevented by using selective deacetylase or proteasomal inhibitors. Moreover, our data demonstrate that Acly’s activity regulates the mechanism underlying Tau mediated neurite morphology defects found in Elp1 KD since both Tau levels and neurites morphology are restored due to Acly overexpression. This suggests a possible involvement of both Tau and Acly dysfunction in Familial Dysautonomia (FD), which is an autosomal recessive peripheral neuropathy caused by mutation in the ELP1 gene that severely affects Elp1 expression levels in the nervous system in FD patients in a similar way as found previously in Elp1 KD neuroblastoma cells.

Baseline Cerebrospinal Fluid α-Synuclein in Parkinson's Disease Is Associated with Disease Progression and Cognitive Decline

Biomarkers are increasingly recognized as tools in the diagnosis and prognosis of neurodegenerative diseases. No fluid biomarker for Parkinson’s disease (PD) has been established to date, but α-synuclein, a major component of Lewy bodies in PD and dementia with Lewy bodies (DLB), has become a promising candidate. Here, we investigated CSF α-synuclein in patients with PD (n = 28), PDD (n = 8), and DLB (n = 5), applying an electrochemiluminescence immunoassay. Median values were non-significantly (p = 0.430) higher in patients with PDD and DLB (287 pg/mL) than in PD (236 pg/mL). A group of n = 36 primarily non-demented patients with PD and PDD was clinically followed for up to two years. A higher baseline α-synuclein was associated with increases in Hoehn and Yahr classifications (p = 0.019) and Beck Depression Inventory scores (p < 0.001) as well as worse performance in Trail Making Test A (p = 0.017), Trail Making Test B (p = 0.043), and the Boston Naming Test (p = 0.002) at follow-up. Surprisingly, higher levels were associated with a better performance in semantic verbal fluency tests (p = 0.046). In summary, CSF α-synuclein may be a potential prognostic marker for disease progression, affective symptoms, and executive cognitive function in PD. Larger-scaled studies have to validate these findings and the discordant results for single cognitive tests in this exploratory investigation.

Parkinsonism and motor neuron disorders: Lessons from Western Pacific ALS/PDC

Recognized worldwide as an unusual "overlap" syndrome, Parkinsonism and motor neuron disease, with or without dementia, is best exemplified by the former high-incidence clusters of Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex (ALS/PDC) in Guam, USA, in the Kii Peninsula of Honshu Island, Japan, and in Papua, Indonesia, on the western side of New Guinea. Western Pacific ALS/PDC is a disappearing neurodegenerative disorder with multiple and sometime overlapping phenotypes (ALS, atypical parkinsonism, dementia) that appear to constitute a single disease of environmental origin, in particular from exposure to genotoxins/neurotoxins in seed of cycad plants (Cycas spp.) formerly used as a traditional source of food (Guam) and/or medicine (Guam, Kii-Japan, Papua-Indonesia). Seed compounds include the principal cycad toxin cycasin, its active metabolite methylazoxymethanol (MAM) and a non-protein amino acid β-N-methylamino-L-alanine (L-BMAA); each reproduces components of ALS/PDC neuropathology when individually administered to laboratory species in single doses perinatally (MAM, L-BMAA) or repeatedly for prolonged periods to young adult animals (L-BMAA). Human exposure to MAM, a potent DNA-alkylating mutagen, also has potential relevance to the high incidence of diverse mutations found among Guamanians with/without ALS/PDC. In sum, seven decades of intensive study of ALS/PDC has revealed field and laboratory approaches leading to discovery of disease etiology that are now being applied to sporadic neurodegenerative disorders such as ALS beyond the Western Pacific region. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

An unusual presentation of Huntington's disease

We describe the case of a 59-year-old woman who exhibited psychotic symptoms, cognitive dysfunction, and restlessness. While the clinical picture and 18F-FDG PET/CT suggested the presence of a tauopathy, especially frontotemporal dementia or progressive supranuclear palsy, genetic testing eventually revealed Huntington's disease.

Of Criteria and Men-Diagnosing Atypical Parkinsonism: Towards an Algorithmic Approach

Diagnosing atypical parkinsonism can be an error-exposed undertaking in the context of elaborate criteria coupled with time restraints on their comprehensive application. We conducted a retrospective, descriptive study of diagnostic accuracy among physicians at two tertiary neurology centers in Romania and developed an algorithmic tool for comparison purposes. As many as 90 patients qualified for inclusion in the study, with 77 patients actually complying with atypical parkinsonism criteria. Overall, physician-established diagnoses may be incorrect in about one-fourth of cases. The reasons for this finding span a wide range of possibilities, from terminology-related inaccuracies to criteria sophistication. A Boolean-logic algorithmic approach to diagnosis might decrease misdiagnosis rates. These findings prepare the ground for the future refinement of an algorithmic application to be fully validated in a prospective study for the benefit of patients and health professionals alike.

Alkoxy glycerol enhanced activity of Oxyresveratrol in Alzheimer's disease by rescuing Tau protein

Alzheimer's disease perpetually demands enormous research on the development of effective treatment strategies. The present study aims to define the role of Oxyresveratrol (OXY) alone and in combination with Alkoxy glycerols (AKG) to reduce Tau protein level and improve the climbing behaviour of Drosophila fly models expressed with human-Tau protein. Oxyresveratrol, a polyphenolic stilbene, possesses a wide range of biological activities like antioxidant, anti-inflammatory, and neuroprotective effects. Nevertheless, chemical instability and low solubility of OXY in aqueous solutions reduce its bioavailability and hinder it from exerting neuroprotective activities. An inclusion complex of OXY with β- cyclodextrin (CD) (OXY-CD complex) was employed in the study for increased dissolution rate and oral availability of OXY. Fish oils and their derivatives have a plethora of applications in in vivo biological activities. Herein, we also remark on the role of AKG in reducing Tau protein level in flies by enhancing OXY-CD activity. Dietary supplementation of OXY-CD together with AKG improved the learning and memory abilities during the climbing assay in Tau flies. The study highlights OXY-CD and AKG as neuroprotective agents and put forward a plausible approach towards the increased permeability of pharmacological agents across the blood-brain barrier (BBB) for the central nervous system elicited by AKG.

Molecular Imaging of Extrapyramidal Movement Disorders With Dementia: The 4R Tauopathies

Two pathologically distinct neurodegenerative conditions, progressive supranuclear palsy and corticobasal degeneration, share in common deposits of tau proteins that differ both molecularly and ultrastructurally from the common tau deposits diagnostic of Alzheimer disease. The proteinopathy in these disorders is characterized by fibrillary aggregates of 4R tau proteins. The clinical presentations of progressive supranuclear palsy and of corticobasal degeneration are often confused with more common disorders such as Parkinson disease or subtypes of frontotemporal lobar degeneration. Neither of these 4R tau disorders has effective therapy, and while there are emerging molecular imaging approaches to identify patients earlier in the course of disease, there are as yet no reliably sensitive and specific approaches to diagnoses in life. In this review, aspects of the clinical syndromes, neuropathology, and molecular biomarker imaging studies applicable to progressive supranuclear palsy and to corticobasal degeneration will be presented. Future development of more accurate molecular imaging approaches is proposed.

Association of MRI Measures With Disease Severity and Progression in Progressive Supranuclear Palsy

Objective: To verify the association of midbrain-based MRI measures as well as cortical volumes with disease core features and progression in patients with Progressive Supranuclear Palsy (PSP). Methods: Sixty-seven patients (52.2% with Richardson's syndrome) were included in the present analysis. Available midbrain-based MRI morphometric assessments as well as cortical lobar volumes were computed. Ocular, gait and postural involvement at the time of MRI was evaluated with the PSP rating scale. Specific milestones or death were used to estimate disease progression up to 72 months follow up. Hierarchical regression models and survival analysis were used for analyzing cross-sectional and longitudinal data, respectively. Results: Multivariate models showed vertical supranuclear gaze palsy was associated with smaller midbrain area (OR: 0.02, 95% CI 0.00-0.175, p = 0.006). Cox regression adjusted for age, disease duration, and phenotype demonstrated that lower midbrain area (HR: 0.122, 95% CI 0.030-0.493, p = 0.003) and diameter (HR: 0.313, 95% CI 0.112-0.878, p = 0.027), higher MR Parkinsonism Index (HR: 6.162, 95% CI 1.790-21.209, p = 0.004) and larger third ventricle width (HR: 2.755, 95% CI 1.068-7.108, p = 0.036) were associated with higher risk of dependency on wheelchair. Conclusions: Irrespective of disease features and other MRI parameters, reduced midbrain size is significantly associated with greater ocular motor dysfunction at the time of MRI and more rapid disease progression over follow up. This is the first comprehensive study to systematically assess the association of available midbrain-based MRI measures and cortical volumes with disease severity and progression in a large cohort of patients with PSP in a real-world setting.

Screening of tau protein kinase inhibitors in a tauopathy-relevant cell-based model of tau hyperphosphorylation and oligomerization

Tauopathies are a class of neurodegenerative disorders characterized by abnormal deposition of post-translationally modified tau protein in the human brain. Tauopathies are associated with Alzheimer's disease (AD), chronic traumatic encephalopathy (CTE), and other diseases. Hyperphosphorylation increases tau tendency to aggregate and form neurofibrillary tangles (NFT), a pathological hallmark of AD. In this study, okadaic acid (OA, 100 nM), a protein phosphatase 1/2A inhibitor, was treated for 24h in mouse neuroblastoma (N2a) and differentiated rat primary neuronal cortical cell cultures (CTX) to induce tau-hyperphosphorylation and oligomerization as a cell-based tauopathy model. Following the treatments, the effectiveness of different kinase inhibitors was assessed using the tauopathy-relevant tau antibodies through tau-immunoblotting, including the sites: pSer202/pThr205 (AT8), pThr181 (AT270), pSer202 (CP13), pSer396/pSer404 (PHF-1), and pThr231 (RZ3). OA-treated samples induced tau phosphorylation and oligomerization at all tested epitopes, forming a monomeric band (46-67 kDa) and oligomeric bands (170 kDa and 240 kDa). We found that TBB (a casein kinase II inhibitor), AR and LiCl (GSK-3 inhibitors), cyclosporin A (calcineurin inhibitor), and Saracatinib (Fyn kinase inhibitor) caused robust inhibition of OA-induced monomeric and oligomeric p-tau in both N2a and CTX culture. Additionally, a cyclin-dependent kinase 5 inhibitor (Roscovitine) and a calcium chelator (EGTA) showed contrasting results between the two neuronal cultures. This study provides a comprehensive view of potential drug candidates (TBB, CsA, AR, and Saracatinib), and their efficacy against tau hyperphosphorylation and oligomerization processes. These findings warrant further experimentation, possibly including animal models of tauopathies, which may provide a putative Neurotherapy for AD, CTE, and other forms of tauopathy-induced neurodegenerative diseases.

Tau affects P53 function and cell fate during the DNA damage response

Cells are constantly exposed to DNA damaging insults. To protect the organism, cells developed a complex molecular response coordinated by P53, the master regulator of DNA repair, cell division and cell fate. DNA damage accumulation and abnormal cell fate decision may represent a pathomechanism shared by aging-associated disorders such as cancer and neurodegeneration. Here, we examined this hypothesis in the context of tauopathies, a neurodegenerative disorder group characterized by Tau protein deposition. For this, the response to an acute DNA damage was studied in neuroblastoma cells with depleted Tau, as a model of loss-of-function. Under these conditions, altered P53 stability and activity result in reduced cell death and increased cell senescence. This newly discovered function of Tau involves abnormal modification of P53 and its E3 ubiquitin ligase MDM2. Considering the medical need with vast social implications caused by neurodegeneration and cancer, our study may reform our approach to disease-modifying therapies.

Martina Sola, Claudia Magrin et al. study the relation between Tau and P53 in response to DNA damage. They uncover an important role for Tau in regulating the stability, and activity of P53 post translationally. Their findings provide insights to potentially common pathways in neurodegenerative disease and cancer.

PET Radiopharmaceuticals for Alzheimer's Disease and Parkinson's Disease Diagnosis, the Current and Future Landscape

Ironically, population aging which is considered a public health success has been accompanied by a myriad of new health challenges, which include neurodegenerative disorders (NDDs), the incidence of which increases proportionally to age. Among them, Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common, with the misfolding and the aggregation of proteins being common and causal in the pathogenesis of both diseases. AD is characterized by the presence of hyperphosphorylated τ protein (tau), which is the main component of neurofibrillary tangles (NFTs), and senile plaques the main component of which is β-amyloid peptide aggregates (Aβ). The neuropathological hallmark of PD is α-synuclein aggregates (α-syn), which are present as insoluble fibrils, the primary structural component of Lewy body (LB) and neurites (LN). An increasing number of non-invasive PET examinations have been used for AD, to monitor the pathological progress (hallmarks) of disease. Notwithstanding, still the need for the development of novel detection tools for other proteinopathies still remains. This review, although not exhaustively, looks at the timeline of the development of existing tracers used in the imaging of Aβ and important moments that led to the development of these tracers.

Xenobiotics, Trace Metals and Genetics in the Pathogenesis of Tauopathies

Tauopathies are a disease group characterized by either pathological accumulation or release of fragments of hyperphosphorylated tau proteins originating from the central nervous system. The tau hypotheses of Parkinson’s and Alzheimer’s diseases contain a clinically diverse spectrum of tauopathies. Studies of case records of various tauopathies may reveal clinical phenotype characteristics of the disease. In addition, improved understanding of different tauopathies would disclose environmental factors, such as xenobiotics and trace metals, that can precipitate or modify the progression of the disorder. Important for diagnostics and monitoring of these disorders is a further development of adequate biomarkers, including refined neuroimaging, or proteomics. Our goal is to provide an in-depth review of the current literature regarding the pathophysiological roles of tau proteins and the pathogenic factors leading to various tauopathies, with the perspective of future advances in potential therapeutic strategies.

Yeast surface display of full-length human microtubule-associated protein tau

Microtubule-associated protein tau is an intrinsically disordered, highly soluble protein found primarily in neurons. Under normal conditions, tau regulates the stability of axonal microtubules and intracellular vesicle transport. However, in patients of neurodegeneration such as Alzheimer's disease (AD), tau forms neurofibrillary deposits, which correlates well with the disease progression. Identifying molecular signatures in tau, such as posttranslational modification, truncation, and conformational change has great potential to detect earliest signs of neurodegeneration and develop therapeutic strategies. Here, we show that full-length human tau, including the longest isoform found in the adult brain, can be robustly displayed on the surface of yeast Saccharomyces cerevisiae. Yeast-displayed tau binds to anti-tau antibodies that cover epitopes ranging from the N-terminus to the 4R repeat region. Unlike tau expressed in the yeast cytosol, surface-displayed tau was not phosphorylated at sites found in AD patients (probed by antibodies AT8, AT270, AT180, and PHF-1). However, yeast-displayed tau showed clear binding to paired helical filament (PHF) tau conformation-specific antibodies Alz-50, MC-1, and Tau-2. Although the tau possessed a conformation found in PHFs, oligomerization or aggregation into larger filaments was undetected. Taken together, yeast-displayed tau enables robust measurement of protein interactions and is of particular interest for characterizing conformational change.

Antisense therapies for movement disorders

Currently, few disease-modifying therapies exist for degenerative movement disorders. Antisense oligonucleotides are small DNA oligonucleotides, usually encompassing ∼20 base pairs, that can potentially target any messenger RNA of interest. Antisense oligonucleotides often contain modifications to the phosphate backbone, the sugar moiety, and the nucleotide base. The development of antisense oligonucleotide therapies spinal muscular atrophy and Duchenne muscular dystrophy suggest potentially wide-ranging therapeutic applications for antisense oligonucleotides in neurology. Successes with these two diseases have heightened interest in academia and the pharmaceutical industry to develop antisense oligonucleotides for several movement disorders, including, spinocerebellar ataxias, Huntington's disease, and Parkinson's disease. Compared to small molecules, antisense oligonucleotide-based therapies have an advantage because the target disease gene sequence is the immediate path to identifying the therapeutically effective complementary antisense oligonucleotide. In this review we describe the different types of antisense oligonucleotide chemistries and their potential use for the treatment of human movement disorders. © 2019 International Parkinson and Movement Disorder Society.

siRNA Blocking of Mammalian Target of Rapamycin (mTOR) Attenuates Pathology in Annonacin-Induced Tauopathy in Mice

Tauopathy is a pathological hallmark of many neurodegenerative diseases. It is characterized by abnormal aggregates of pathological phosphotau and somatodendritic redistribution. One suggested strategy for treating tauopathy is to stimulate autophagy, hence, getting rid of these pathological protein aggregates. One key controller of autophagy is mTOR. Since stimulation of mTOR leads to inhibition of autophagy, inhibitors of mTOR will cause stimulation of autophagy process. In this report, tauopathy was induced in mice using annonacin. Blocking of mTOR was achieved through stereotaxic injection of siRNA against mTOR. The behavioral and immunohistochemical evaluation revealed the development of tauopathy model as proven by deterioration of behavioral performance in open field test and significant tau aggregates in annonacin-treated mice. Blocking of mTOR revealed significant clearance of tau aggregates in the injected side; however, tau expression was not affected by mTOR blockage.

4',6-Diamidino-2-Phenylindole Distinctly Labels Tau Deposits

Tau deposits have distinct biochemical characteristics and vary morphologically based on identification with tau antibodies and several chemical dyes. Here, we report 4',6-diamidino-2-phenylindole (DAPI)-positivity of tau deposits. Furthermore, we investigated the cause for this positivity. DAPI was positive in 3R/4R (3-repeat/4-repeat) tau deposits in Alzheimer's disease, myotonic dystrophy, and neurodegeneration with brain iron accumulation, and in 4R tau deposits in corticobasal degeneration, but negative in 4R tau deposits in frontotemporal dementia with parkinsonism-17 and progressive supranuclear palsy. The peak emission wavelength of DAPI after binding to a tau deposit was similar to that after binding to a nucleus. This DAPI-positivity was conspicuous at the optimum concentration of 2 μg/ml. DAPI-positivity was diminished after formic acid treatment, but preserved after nucleic acid elimination and phosphate moiety blocking. Our results suggest that staining with 2 μg/ml DAPI is a common but useful tool to differentially detect tau deposits in various tauopathies.

Untangling the Tauopathy for Alzheimer's disease and parkinsonism

Tau is a microtubule-associated protein that mainly localizes to the axon to stabilize axonal microtubule structure and neuronal connectivity. Tau pathology is one of the most common proteinopathies that associates with age-dependent neurodegenerative diseases including Alzheimer's disease (AD), and various Parkinsonism. Tau protein undergoes a plethora of intra-molecular modifications and some altered forms promote the production of toxic oligomeric tau and paired helical filaments, and through which further assemble into neurofibrillary tangles, also known as tauopathy. In this review, we will discuss the recent advances of the tauopathy research, primarily focusing on its association with the early axonal manifestation of axonal transport defect, axonal mitochondrial stress, autophagic vesicle accumulation and the proceeding of axon destruction, and the pathogenic Tau spreading across the synapse. Two alternative strategies either by targeting tau protein itself or by improving the age-related physiological decline are currently racing to find the hopeful treatment for tauopathy. Undoubtedly, more studies are needed to combat this devastating condition that has already affected millions of people in our aging population.

Traumatic Brain Injury and Firearm Use and Risk of Progressive Supranuclear Palsy Among Veterans

Background: Progressive supranuclear palsy (PSP) is a tauopathy that has a multifactorial etiology. Numerous studies that have investigated lead exposure and traumatic brain injury (TBI) as risk factors for other tauopathies, such as Alzheimer's disease, but not for PSP.

Objective: We sought to investigate the role of firearm usage, as a possible indicator of lead exposure, and TBI as risk factors for PSP in a population of military veterans.

Methods: We included participants from a larger case-control study who reported previous military service. Our sample included 67 PSP cases and 68 controls. Participants were administered a questionnaire to characterize firearm use in the military and occurrence of TBI.

Results: Cases were significantly less educated than controls. In unadjusted analyses, the proportion of PSP cases (80.6%) and controls (64.7%) who reported use of firearms as part of their military job was positively associated with PSP, odds ratio (OR) 2.2 (95% CI: 1–5.0). There were no significant case-control differences in mean service duration. There was only a weak association with history of TBI, OR 1.6 (95% CI: 0.8–3.4). In multivariate models, firearm usage (OR 3.7, 95% CI: 1.5, 9.8) remained significantly associated with PSP.

Conclusions: Our findings show a positive association between firearm usage and PSP and an inverse association between education and PSP. The former suggests a possible etiologic role of lead. Further studies are needed to confirm the potential etiologic effects of metals on PSP.

The study was registered in clinicaltrials.gov. ClinicalTrials.gov Identifier: NCT00431301.

Tubulin and Tau: Possible targets for diagnosis of Parkinson's and Alzheimer's diseases

Neurodegenerative diseases including Alzheimer’s disease (AD) and Parkinson’s disease (PD) are characterized by progressive neuronal loss and pathological accumulation of some proteins. Developing new biomarkers for both diseases is highly important for the early diagnosis and possible development of neuro-protective strategies. Serum antibodies (AIAs) against neuronal proteins are potential biomarkers for AD and PD that may be formed in response to their release into systemic circulation after brain damage. In the present study, two AIAs (tubulin and tau) were measured in sera of patients of PD and AD, compared to healthy controls. Results showed that both antibodies were elevated in patients with PD and AD compared to match controls. Curiously, the profile of elevation of antibodies was different in both diseases. In PD cases, tubulin and tau AIAs levels were similar. On the other hand, AD patients showed more elevation of tau AIAs compared to tubulin. Our current results suggested that AIAs panel could be able to identify cases with neuro-degeneration when compared with healthy subjects. More interestingly, it is possible to differentiate between PD and AD cases through identifying specific AIAs profile for each neurodegenerative states.

Autophagy induction by trehalose: Molecular mechanisms and therapeutic impacts

The balance between synthesis and degradation is crucial to maintain cellular homeostasis and different mechanisms are known to keep this balance. In this review, we will provide a short overview on autophagy as an intracellular homeostatic degradative machinery. We will also describe the involvement of downregulation of autophagy in numerous diseases including neurodegenerative diseases, cancer, aging, metabolic disorders, and other infectious diseases. Therefore, modulation of autophagic processes can represent a promising way of intervention in different diseases including neurodegeneration and cancer. Trehalose, also known as mycose, is a natural disaccharide found extensively but not abundantly among several organisms. It is described that trehalose can work as an important autophagy modulator and can be proficiently used in the control several diseases in which autophagy plays an important role. On these bases, we describe here the role of trehalose as an innovative drug in the treatment of neurodegenerative diseases and other illnesses opening a new scenario of intervention in conditions difficult to be treated.

Dual mTORC1/mTORC2 blocker as a possible therapy for tauopathy in cellular model

Tauopathy comprises a group of disorders caused by abnormal aggregates of tau protein. In these disorders phosphorylated tau protein tends to accumulate inside neuronal cells (soma) instead of the normal axonal distribution of tau. A suggested therapeutic strategy for tauopathy is to induce autophagy to increase the ability to get rid of the unwanted tau aggregates. One of the key controllers of autophagy is mTOR. Blocking mTOR leads to stimulation of autophagy. Recently, unravelling molecular structure of mTOR showed that it is formed of two subunits: mTORC1/C2. So, blocking both subunits of mTOR seems more attractive as it will explore all abilities of mTOR molecule. In the present study, we report using pp242 which is a dual mTORC1/C2 blocker in cellular model of tauopathy using LUHMES cell line. Adding fenazaquin to LUHMES cells induced tauopathy in the form of increased phospho tau aggregates. Moreover, fenazaquin treated cells showed the characteristic somatic redistribution of tau. PP242 use in the present tauopathy model reversed the pathology significantly without observable cellular toxicity for the used dosage of 1000 nM. The present study suggests the possible use of pp242 as a dual mTOR blocker to treat tauopathy.

Microtubule defects in mesenchymal stromal cells distinguish patients with Progressive Supranuclear Palsy

Progressive Supranuclear Palsy (PSP) is a rare neurodegenerative disease whose etiopathogenesis remains elusive. The intraneuronal accumulation of hyperphosphorylated Tau, a pivotal protein in regulating microtubules (MT), leads to include PSP into tauopathies. Pathological hallmarks are well known in neural cells but no word yet if PSP‐linked dysfunctions occur also in other cell types. We focused on bone marrow mesenchymal stromal cells (MSCs) that have recently gained attention for therapeutic interventions due to their anti‐inflammatory, antiapoptotic and trophic properties. Here, we aimed to investigate MSCs biology and to disclose if any disease‐linked defect occurs in this non‐neuronal compartment. First, we found that cells obtained from patients showed altered morphology and growth. Next, Western blotting analysis unravelled the imbalance in α‐tubulin post‐translational modifications and in MT stability. Interestingly, MT mass is significantly decreased in patient cells at baseline and differently changes overtime compared to controls, suggesting their inability to efficiently remodel MT cytoskeleton during ageing in culture. Thus, our results provide the first evidence that defects in MT regulation and stability occur and are detectable in a non‐neuronal compartment in patients with PSP. We suggest that MSCs could be a novel model system for unravelling cellular processes implicated in this neurodegenerative disorder.

The Role of Stress as a Risk Factor for Progressive Supranuclear Palsy

BACKGROUND

PSP, like Alzheimer's disease (AD), is a tauopathy. The etiopathogenesis of PSP is not well known and the role of stress has not yet been examined. Recent studies have shown that stress increases the risk for developing AD. This study investigates the role of stress as a risk factor for PSP.

OBJECTIVE

B To examine the association between the development of progressive supranuclear palsy (PSP) and self-reported life stressors.

METHODS

76 patients diagnosed with PSP according to the NINDS-SPSP criteria and 68 age-matched unrelated controls were administered a life stressor questionnaire. Stress was quantified as total number of events, number of life changing events, and number of events characterized by self-rated severity. Conditional odds ratio (OR) was calculated for each measure, with participants in the highest quartile of each measure being defined as high-exposure in relation to all other participants.

RESULTS

There were no significant differences between the reported number of total events or life-changing events in cases and controls. However, we found 24.4% of cases (N = 11) and 9.1% of controls (N = 5) had a higher exposure to high severity events, yielding an OR of 3.2 (p = 0.04).

CONCLUSIONS

We found that cases have over a three times greater odds of high exposure to high-severity events than controls prior to the clinical development of PSP, while there were no differences in overall number of reported events. Our findings suggest that high exposure to highly stressful events may be associated with the development of PSP.

Cognitive dysfunction in corticobasal degeneration

Corticobasal degeneration (CBD) was originally described as a distinct clinicopathological entity in 1967. Since then, different phenotypic presentations have emerged as possible manifestations of CBD histopathological findings. In addition, pathophysiological findings and the molecular basis have been delineated and several aspects of its cognitive manifestations have been clarified. Thus, not only the spectrum of what is currently designated as CBD has expanded, but overlap with other degenerative and even secondary disorders has made clinical diagnostic certainty even more challenging in the absence of specific and readily-available markers. Cognitive deficits in CBD are now recognized as a frequent initial presentation and may appear up to eight years before the motor symptoms, depending on the phenotypic variant. Characteristic cognitive features of CBD involve language deficits, visuospatial and executive dysfunctions, apraxia, and behavioral disorders. Semantic and episodic memories are usually preserved, while language is often impaired in the early stages.

Discovery and characterization of stable and toxic Tau/phospholipid oligomeric complexes

The microtubule-associated protein Tau plays a central role in the pathogenesis of Alzheimer’s disease. Although Tau interaction with membranes is thought to affect some of its physiological functions and its aggregation properties, the sequence determinants and the structural and functional consequences of such interactions remain poorly understood. Here, we report that the interaction of Tau with vesicles results in the formation of highly stable protein/phospholipid complexes. These complexes are toxic to primary hippocampal cultures and are detected by MC-1, an antibody recognizing pathological Tau conformations. The core of these complexes is comprised of the PHF6* and PHF6 hexapeptide motifs, the latter in a β-strand conformation. Studies using Tau-derived peptides enabled the design of mutants that disrupt Tau interactions with phospholipids without interfering with its ability to form fibrils, thus providing powerful tools for uncoupling these processes and investigating the role of membrane interactions in regulating Tau function, aggregation and toxicity.

The Alzheimer protein Tau interacts with biological membranes, but the role of these interactions in regulating Tau function in health and disease remains unexplored. Here, the authors report on the discovery and characterization of neurotoxic oligomeric protein/phospholipid complexes.

Annonaceae: Breaking the Wall of Inflammation

Inventories of tropical forests have listed Annonaceae as one of the most diverse plant families. For centuries, it is employed in traditional medicines to cure various pathological conditions including snakebite, analgesic, astringent, diarrhea, dysentery, arthritis pain, rheumatism, neuralgia, and weight loss etc. Phytochemical analysis of Annonaceae family have reported the occurrence of alkaloids, flavonoids, triterpenes, diterpenes and diterpene flavone glycosides, sterols, lignans, and annonaceous acetogenin characteristically affiliated with Annonaceae sp. Numerous past studies have underlined the pleotropic pharmacological activities of the crude extracts and isolated compounds from Annonaceae species. This review is an effort to abridge the ethnobotany, morphology, phytochemistry, toxicity, and particularly focusing on the anti-inflammatory activity of the Annonaceae species.

Small-molecule PET Tracers for Imaging Proteinopathies

In this chapter, we provide a review of the challenges and advances in developing successful PET imaging agents for 3 major types of aggregated amyloid proteins: amyloid-beta (Aβ), tau, and alpha-synuclein (α-syn). These 3 amyloids are involved in the pathogenesis of a variety of neurodegenerative diseases, referred to as proteinopathies or proteopathies, that include Alzheimer disease, Lewy body dementias, multiple system atrophy, and frontotemporal dementias, among others. In the Introduction section, we briefly discuss the history of amyloid in neurodegenerative diseases and describe why progress in developing effective imaging agents has been hampered by the failure of crystallography to provide definitive ligand-protein interactions for rational radioligand design efforts. Instead, the field has relied on largely serendipitous, trial-and-error methods to achieve useful and specific PET amyloid imaging tracers for Aβ, tau, and α-syn deposits. Because many of the proteopathies involve more than 1 amyloid protein, it is important to develop selective PET tracers for the different amyloids to help assess the relative contribution of each to total amyloid burden. We use Pittsburgh compound B to illustrate some of the critical steps in developing a potent and selective Aβ PET imaging agent. Other selective Aβ and tau PET imaging compounds have followed similar pathways in their developmental processes. Success for selective α-syn PET imaging agents has not been realized yet, but work is ongoing in multiple laboratories throughout the world. In the tau sections, we provide background regarding 3-repeat (3R) and 4-repeat (4R) tau proteins and how they can affect the binding of tau radioligands in different tauopathies. We review the ongoing efforts to assess the properties of tau ligands, which are useful in 3R, 4R, or combined 3R-4R tauopathies. Finally, we describe in the α-syn sections recent attempts to develop selective tracers to image α-synucleinopathies.

Imaging tau pathology in Parkinsonisms

The recent development of positron emission tomography radiotracers targeting pathological tau in vivo has led to numerous human trials. While investigations have primarily focused on the most common tauopathy, Alzheimer's disease, it is imperative that testing also be performed in parkinsonian tauopathies, such as progressive supranuclear palsy, corticobasal degeneration, and frontotemporal dementia and parkinsonism linked to chromosome 17. Tau aggregates differ in isoforms and conformations across disorders, and as a result one radiotracer may not be appropriate for all tauopathies. In this review, we evaluate the preclinical and clinical reports of current tau radiotracers in parkinsonian disorders. These radiotracers include [18F]FDDNP, [11C]PBB3, [18F]THK-5317, [18F]THK-5351, and [18F]AV-1451 ([18F]T807). There are concerns of off-target binding with [18F]FDDNP and [11C]PBB3, which may increase the signal to noise ratio and thereby decrease the efficacy of these radiotracers. Testing in [18F]THK-5317, [18F]THK-5351, and [18F]AV-1451 has been performed in progressive supranuclear palsy, while [18F]THK-5317 and [18F]AV-1451 have also been tested in corticobasal degeneration patients. [18F]THK-5317 and [18F]THK-5351 have demonstrated binding in brain regions known to be afflicted with pathological tau; however, due to small sample sizes these studies should be replicated before concluding their appropriateness in parkinsonian tauopathies. [18F]AV-1451 has demonstrated mixed results in progressive supranuclear palsy patients and post-mortem analysis shows minimal to no binding to non-Alzheimer's disease tauopathies brain slices.

Involvement of tau phosphorylation in traumatic brain injury patients

OBJECTIVES

Traumatic brain injury (TBI) results in significant morbidity and mortality throughout the world. In TBI patients suffering cognitive, emotional, and behavioral deficits, the leading cause derives from the physical injury to the central nervous system (CNS) that impairs brain function.

MATERIALS AND METHODS

Here, we applied a targeted approach to understand the potential mechanisms of neuron damage after TBI. Tau protein phosphorylation was compared in the brain tissues collected from patients underwent brain surgery based on the assessment of brain injury extent by Glasgow Coma Scale (GCS).

RESULTS

The results indicated that the levels of phosphorylated tau were significantly higher in the severe and extremely severe TBI groups, compared to the moderate group of patients. Phosphorylated, but not the total tau protein was uniquely correlated with the GCS score (R² =.7849, P<.01) in 142 TBI patients. Consistently, the activities of key players associated with tau hyperphosphorylation GSK-3β and PP2A showed parallel correlations with the severity of TBI as well.

CONCLUSION

These data suggest that the enhanced tau protein phosphorylation occurs upon severe neuron injures and may contribute to the pathological structural changes of CNS leading to brain damage of TBI.

Intrinsic functional connectivity alterations in progressive supranuclear palsy: Differential effects in frontal cortex, motor, and midbrain networks

BACKGROUND

The topography of functional network changes in progressive supranuclear palsy can be mapped by intrinsic functional connectivity MRI. The objective of this study was to study functional connectivity and its clinical and behavioral correlates in dedicated networks comprising the cognition-related default mode and the motor and midbrain functional networks in patients with PSP.

METHODS

Whole-brain-based "resting-state" functional MRI and high-resolution T1-weighted magnetic resonance imaging data together with neuropsychological and video-oculographic data from 34 PSP patients (22 with Richardson subtype and 12 with parkinsonian subtype) and 35 matched healthy controls were subjected to network-based functional connectivity and voxel-based morphometry analysis.

RESULTS

After correction for global patterns of brain atrophy, the group comparison between PSP patients and controls revealed significantly decreased functional connectivity (P < 0.05, corrected) in the prefrontal cortex, which was significantly correlated with cognitive performance (P = 0.006). Of note, midbrain network connectivity in PSP patients showed increased connectivity with the thalamus, on the one hand, whereas, on the other hand, lower functional connectivity within the midbrain was significantly correlated with vertical gaze impairment, as quantified by video-oculography (P = 0.004). PSP Richardson subtype showed significantly increased functional motor network connectivity with the medial prefrontal gyrus.

CONCLUSIONS

PSP-associated neurodegeneration was attributed to both decreased and increased functional connectivity. Decreasing functional connectivity was associated with worse behavioral performance (ie, dementia severity and gaze palsy), whereas the pattern of increased functional connectivity may be a potential adaptive mechanism. © 2017 International Parkinson and Movement Disorder Society.

The hidden Niemann-Pick type C patient: clinical niches for a rare inherited metabolic disease

BACKGROUND

Niemann-Pick disease type C (NP-C) is a rare, inherited neurodegenerative disease of impaired intracellular lipid trafficking. Clinical symptoms are highly heterogeneous, including neurological, visceral, or psychiatric manifestations. The incidence of NP-C is under-estimated due to under-recognition or misdiagnosis across a wide range of medical fields. New screening and diagnostic methods provide an opportunity to improve detection of unrecognized cases in clinical sub-populations associated with a higher risk of NP-C. Patients in these at-risk groups ("clinical niches") have symptoms that are potentially related to NP-C, but go unrecognized due to other, more prevalent clinical features, and lack of awareness regarding underlying metabolic causes.

METHODS

Twelve potential clinical niches identified by clinical experts were evaluated based on a comprehensive, non-systematic review of literature published to date. Relevant publications were identified by targeted literature searches of EMBASE and PubMed using key search terms specific to each niche. Articles published in English or other European languages up to 2016 were included.

FINDINGS

Several niches were found to be relevant based on available data: movement disorders (early-onset ataxia and dystonia), organic psychosis, early-onset cholestasis/(hepato)splenomegaly, cases with relevant antenatal findings or fetal abnormalities, and patients affected by family history, consanguinity, and endogamy. Potentially relevant niches requiring further supportive data included: early-onset cognitive decline, frontotemporal dementia, parkinsonism, and chronic inflammatory CNS disease. There was relatively weak evidence to suggest amyotrophic lateral sclerosis or progressive supranuclear gaze palsy as potential niches.

CONCLUSIONS

Several clinical niches have been identified that harbor patients at increased risk of NP-C.

Skin disorders in Parkinson's disease: potential biomarkers and risk factors

Parkinson’s disease (PD) is one of the most common neurodegenerative disorders, characterized by a symptom triad comprising resting tremor, rigidity, and akinesia. In addition, non-motor symptoms of PD are well recognized and often precede the overt motor manifestations. Cutaneous manifestations as markers of PD have long been discussed, and cumulative evidence shows an increased prevalence of certain dermatological disorders in PD. Seborrheic dermatitis is considered to occur as a premotor feature of PD referable to dysregulation of the autonomic nervous system. Also, an increased risk of melanoma has been observed in PD. Light hair color is a known risk factor for melanoma, and interestingly the risk of PD is found to be significantly higher in individuals with light hair color and particularly with red hair. Furthermore, several studies have reported a high prevalence of PD in patients with bullous pemphigoid. Moreover, a 2-fold increase in risk of new-onset PD has been observed in patients with rosacea. Besides the association between PD and various dermatological disorders, the skin may be useful in the diagnosis of PD. Early PD pathology is found not only in the brain but also in extra-neuronal tissues. Thus, the protein α-synuclein, which is genetically associated with PD, is present not only in the CNS but also in the skin. Hence, higher values of α-synuclein have been observed in the skin of patients with PD. Furthermore, an increased risk of PD has been found in the Cys/Cys genotype, which is associated with red hair color. In this review, we summarize the current evidence of the association between PD and dermatological disorders, the cutaneous adverse effects of neurological medications, and describe the potential of skin protein expression and biomarkers in identification of risk and diagnosis of PD.

A critical review of the postulated role of the non-essential amino acid, β-N-methylamino-L-alanine, in neurodegenerative disease in humans

The compound BMAA (β-N-methylamino-L-alanine) has been postulated to play a significant role in four serious neurological human diseases: Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) found on Guam, and ALS, Parkinsonism, and dementia that occur globally. ALS/PDC with symptoms of all three diseases first came to the attention of the scientific community during and after World War II. It was initially associated with cycad flour used for food because BMAA is a product of symbiotic cycad root-dwelling cyanobacteria. Human consumption of flying foxes that fed on cycad seeds was later suggested as a source of BMAA on Guam and a cause of ALS/PDC. Subsequently, the hypothesis was expanded to include a causative role for BMAA in other neurodegenerative diseases including Alzheimer's disease (AD) through exposures attributed to proximity to freshwaters and/or consumption of seafood due to its purported production by most species of cyanobacteria. The hypothesis that BMAA is the critical factor in the genesis of these neurodegenerative diseases received considerable attention in the medical, scientific, and public arenas. This review examines the history of ALS/PDC and the BMAA-human disease hypotheses; similarities and differences between ALS/PDC and the other diseases with similar symptomologies; the relationship of ALS/PDC to other similar diseases, studies of BMAA-mediated effects in lab animals, inconsistencies and data gaps in the hypothesis; and other compounds and agents that were suggested as the cause of ALS/PDC on Guam. The review concludes that the hypothesis of a causal BMAA neurodegenerative disease relationship is not supported by existing data.

Assessment of Olfactory Function in MAPT-Associated Neurodegenerative Disease Reveals Odor-Identification Irreproducibility as a Non-Disease-Specific, General Characteristic of Olfactory Dysfunction

Olfactory dysfunction is associated with normal aging, multiple neurodegenerative disorders, including Parkinson's disease, Lewy body disease and Alzheimer's disease, and other diseases such as diabetes, sleep apnea and the autoimmune disease myasthenia gravis. The wide spectrum of neurodegenerative disorders associated with olfactory dysfunction suggests different, potentially overlapping, underlying pathophysiologies. Studying olfactory dysfunction in presymptomatic carriers of mutations known to cause familial parkinsonism provides unique opportunities to understand the role of genetic factors, delineate the salient characteristics of the onset of olfactory dysfunction, and understand when it starts relative to motor and cognitive symptoms. We evaluated olfactory dysfunction in 28 carriers of two MAPT mutations (p.N279K, p.P301L), which cause frontotemporal dementia with parkinsonism, using the University of Pennsylvania Smell Identification Test. Olfactory dysfunction in carriers does not appear to be allele specific, but is strongly age-dependent and precedes symptomatic onset. Severe olfactory dysfunction, however, is not a fully penetrant trait at the time of symptom onset. Principal component analysis revealed that olfactory dysfunction is not odor-class specific, even though individual odor responses cluster kindred members according to genetic and disease status. Strikingly, carriers with incipient olfactory dysfunction show poor inter-test consistency among the sets of odors identified incorrectly in successive replicate tests, even before severe olfactory dysfunction appears. Furthermore, when 78 individuals without neurodegenerative disease and 14 individuals with sporadic Parkinson's disease were evaluated twice at a one-year interval using the Brief Smell Identification Test, the majority also showed inconsistency in the sets of odors they identified incorrectly, independent of age and cognitive status. While these findings may reflect the limitations of these tests used and the sample sizes, olfactory dysfunction appears to be associated with the inability to identify odors reliably and consistently, not with the loss of an ability to identify specific odors. Irreproducibility in odor identification appears to be a non-disease-specific, general feature of olfactory dysfunction that is accelerated or accentuated in neurodegenerative disease. It may reflect a fundamental organizational principle of the olfactory system, which is more "error-prone" than other sensory systems.

Primary Progressive Orofacial Apraxia: A Ten-Year Long Follow-Up Case Report

Orofacial apraxia (OA) as the main symptom in neurodegenerative disorders has not been yet reported. We present the case of a woman with a 22-month long history of isolated OA, studied with cerebrospinal fluid biomarkers and repeated clinical, neuropsychological, and morpho-functional evaluations. Baseline morpho-functional neuroimages revealed a left frontal operculum hypoperfusion with a widespread fronto-temporal involvement at follow-up. Cerebrospinal fluid concentrations of tau and amyloid-β were normal. The ten-year long clinical observation disclosed progressive OA worsening and the late onset of frontal functions impairment and extrapyramidal signs. The early and late stages of a neurodegenerative syndrome with OA as the main clinical feature were characterized.

Progressive Supranuclear Palsy and Corticobasal Degeneration: Pathophysiology and Treatment Options

OPINION STATEMENT

There are currently no disease-modifying treatments for progressive supranuclear palsy (PSP) or corticobasal degeneration (CBD), and no approved pharmacological or therapeutic treatments that are effective in controlling their symptoms. The use of most pharmacological treatment options are based on experience in other disorders or from non-randomized historical controls, case series, or expert opinion. Levodopa may provide some improvement in symptoms of Parkinsonism (specifically bradykinesia and rigidity) in PSP and CBD; however, evidence is conflicting and where present, benefits are often negligible and short lived. In fact, "poor" response to levodopa forms part of the NINDS-SPSP criteria for the diagnosis of PSP and consensus criteria for the diagnosis of CBD (Lang Mov Disord. 20 Suppl 1:S83-91, 2005; Litvan et al. Neurology. 48:119-25, 1997; Armstrong et al. Neurology. 80(5):496-503, 2013). There is some evidence that intrasalivery gland botulinum toxin is useful in managing problematic sialorrhea and that intramuscular botulinum toxin and baclofen are helpful in reducing dystonia, including blepharospasm. Benzodiazepines may also be useful in managing dystonia. Myoclonus may be managed using levetiracetam and benzodiazepines. Pharmacological agents licensed for Alzheimer's disease (such as acetylcholinesterase inhibitors and N-Methyl-D-aspartate receptor antagonists) have been used off-label in PSP, CBD, and other tauopathies with the aim of improving cognition; however, there is limited evidence that they are effective and risk of adverse effects may outweigh benefits. The use of atypical antipsychotics for behavioural symptoms is not recommended in the elderly or those with demetia associated conditions and most antipsychotics will worsen Parkinsonism. Antidepressants may be useful for behavioral symptoms and depression but are often poorly tolerated due to adverse effects. In the absence of an effective drug treatment to target the underlying cause of CBD and PSP, management should focus on optimizing quality of life, relieving symptoms and assisting patients with their activities of daily living (ADL). Patients should be managed by a multidisciplinary team consisting of neurologists, physiotherapists (PT), occupational therapists (OT), speech and language therapists (SALT), dieticians, ophthalmologists, psychologists, and palliative care specialists.

Voxel-based morphometry to detect effect of APOE on brain gray matter changes in Parkinson's Disease

The goal of the study was to determine association between APOE Ɛ4 and gray matter changes in PD patients, with or without dementia. Twenty-five PD patients with the APOE Ɛ4 (13 with dementia), 24 without Ɛ4 (12 with dementia), and 26 controls were selected. We found no significant differences between PD patients and controls, or between PD patients with and without the APOE Ɛ4 allele, with regard to VBM analysis. Our results provide no evidence of an association of the APOE Ɛ4 and gray matter degenerative changes in patients with PD, either with or without dementia.

Genetics in Parkinson disease: Mendelian versus non-Mendelian inheritance

Parkinson's disease is a common, progressive neurodegenerative disorder, affecting 3% of those older than 75 years of age. Clinically, Parkinson's disease (PD) is associated with resting tremor, postural instability, rigidity, bradykinesia, and a good response to levodopa therapy. Over the last 15 years, numerous studies have confirmed that genetic factors contribute to the complex pathogenesis of PD. Highly penetrant mutations producing rare, monogenic forms of the disease have been discovered in singular genes such as SNCA, Parkin, DJ-1, PINK 1, LRRK2, and VPS35. Unique variants with incomplete penetrance in LRRK2 and GBA have been shown to be strong risk factors for PD in certain populations. Additionally, over 20 common variants with small effect sizes are now recognized to modulate the risk for PD. Investigating Mendelian forms of PD has provided precious insight into the pathophysiology that underlies the more common idiopathic form of disease; however, no treatment methodologies have developed. Furthermore, for identified common risk alleles, the functional basis underlying risk principally remains unknown. The challenge over the next decade will be to strengthen the findings delivered through genetic discovery by assessing the direct, biological consequences of risk variants in tandem with additional high-content, integrated datasets. This review discusses monogenic risk factors and mechanisms of Mendelian inheritance of Parkinson disease. Highly penetrant mutations in SNCA, Parkin, DJ-1, PINK 1, LRRK2 and VPS35 produce rare, monogenic forms of the disease, while unique variants within LRRK2 and GBA show incomplete penetrance and are strong risk factors for PD. Additionally, over 20 common variants with small effect sizes modulate disease risk. The challenge over the next decade is to strengthen genetic findings by assessing direct, biological consequences of risk variants in tandem with high-content, integrated datasets. This article is part of a special issue on Parkinson disease.

Tau protein as a biomarker for asphyxia: A possible forensic tool?

Asphyxial death has been a problem for forensic investigations due to the absence of a validated biomarker for the diagnosis of this event. Recently, research on brain affection by asphyxia raised hopes on the possible use of CNS markers for asphyxia. The cytoskeletal proteins seem to be attractive targets as they are vulnerable to hypoxia and can be affected in asphyxial deaths. Tau, an important cytoskeletal protein, showed affection in many neurodegenerative disorders and recently in some acute incidences like trauma and brain ischemia. In this report we show the affection of the normal pattern of tau and pathological aggregates of tau in the case of brain hypoxia. This may give new clues to asphyxial death investigations.

Genetic substrates of psychosis in patients with Parkinson's disease: A critical review

Patients with Parkinson's disease (PD) may develop several non-motor symptoms such as psychosis, depression, cognitive impairment, autonomic disturbances and sleep disturbances. Psychosis is one of the common non-motor symptoms, which commonly manifests as visual hallucinations and minor hallucinations such as sense of passage and presence. Though long-term dopaminergic therapy, longer duration of PD and cognitive impairment have been described as risk factors for emergence of psychosis in PD, predicting psychosis in PD remains challenging. Multiple studies have explored the genetic basis of psychosis in PD by studying polymorphisms of several genes. Most of the studies have focused on apolipoprotein E polymorphism followed by polymorphisms in cholecystokinin (CCK) system, dopamine receptors and transporters, HOMER gene, serotonin, catechol-o-methyltransferase, angiotensin converting enzyme and tau. Other than the studies on polymorphisms of CCK, most of the studies have reported conflicting results regarding association with psychosis in PD. Three out of four studies on CCK polymorphism have reported significant association of -45C>T polymorphism with the presence of hallucinations. The discrepancies in the results across the studies reviewed are possibly due to racial differences as well as differences in the patient characteristics. This review critically analyzes the published studies on genetic polymorphisms in patients with PD and psychosis.

Parkinsonism, movement disorders and genetics in frontotemporal dementia

Frontotemporal dementia (FTD) refers to a group of clinically and genetically heterogeneous neurodegenerative disorders that are a common cause of adult-onset behavioural and cognitive impairment. FTD often presents in combination with various hyperkinetic or hypokinetic movement disorders, and evidence suggests that various genetic mutations underlie these different presentations. Here, we review the known syndromatic-genetic correlations in FTD. Although no direct genotype-phenotype correlations have been identified, mutations in multiple genes have been associated with various presentations. Mutations in the genes that encode microtubule-associated protein tau (MAPT) and progranulin (PGRN) can manifest as symmetrical parkinsonism, including the phenotypes of Richardson syndrome and corticobasal syndrome (CBS). Expansions in the C9orf72 gene are most frequently associated with familial FTD, typically combined with motor neuron disease, but other manifestations, such as symmetrical parkinsonism, CBS and multiple system atrophy-like presentations, have been described in patients with these mutations. Less common gene mutations, such as those in TARDBP, CHMP2B, VCP, FUS and TREM2, can also present as atypical parkinsonism. The most common hyperkinetic movement disorders in FTD are motor and vocal stereotypies, which have been observed in up to 78% of patients with autopsy-proven FTD. Other hyperkinetic movements, such as chorea, orofacial dyskinesias, myoclonus and dystonia, are also observed in some patients with FTD.

Parkinson disease and progressive supranuclear palsy: protein expression in skin

Objective

This study characterizes the expression of tau (p‐tau) and α‐synuclein (α‐syn) by immunohistochemistry in the skin of three different populations: healthy control (HC), Parkinson disease (PD), and progressive supranuclear paralysis (PSP) subjects, with the purpose of finding a biomarker that could differentiate between subjects with PD and PSP.

Material and Methods

We evaluated the presence of p‐tau and α‐syn in a pilot study in the skin of three distinct groups of patients: 17 healthy subjects, 17 patients with PD, and 10 patients with PSP. Four millimeters punch biopsies were obtained from the occipital area and analyzed by immunohistochemistry using antibodies against α‐syn and phosphorylated species of tau. PHF (paired helical filaments) antibody identifies p‐tau in both normal and pathological conditions and AT8 recognizes p‐tau characteristic of pathological conditions. Differences between the three groups were assessed by quantification of immunopositive areas in the epidermis.

Results

The immunopositivity pattern of p‐tau and α‐syn was significantly different among the three groups. Healthy subjects showed minimal staining using AT8 and α‐syn. The PD group showed significantly higher α‐syn and AT8 immunopositivity, while the PSP group only expressed higher AT8 immunopositivity than HCs.

Conclusion

These data suggest that the skin reflects brain pathology. Therefore, immunohistochemical analysis of p‐tau and α‐syn in the skin can be useful for further characterization of PD and PSP.