Serum Beta-Synuclein Is Higher in Down Syndrome and Precedes Rise of pTau181.

This exploratory case-control study investigates the synaptic marker beta-synuclein in serum and plasma pTau181 in adults with Down syndrome (DS) with (sDS, n = 14) and without (aDS, n = 47) clinical symptoms of Alzheimer disease (AD) as well as euploid controls (n = 23). Beta-synuclein was higher in aDS and more pronounced in sDS (p < 0.0001), whereas pTau181 was only higher in sDS (p < 0.0001). Both markers showed good discriminatory power (area under the curve > 0.90) to distinguish symptomatic from asymptomatic AD. The data indicate that synaptic alterations belong to the earliest AD-associated events in DS and highlight the value of serum beta-synuclein as a potential early marker of AD. ANN NEUROL 2022;92:6-10.

Herpes simplex virus and rates of cognitive decline or whole brain atrophy in the Dominantly Inherited Alzheimer Network.

OBJECTIVE: To investigate whether herpes simplex virus type 1 (HSV-1) infection was associated with rates of cognitive decline or whole brain atrophy among individuals from the Dominantly Inherited Alzheimer Network (DIAN). METHODS: Among two subsets of the DIAN cohort (age range 19.6-66.6 years; median follow-up 3.0 years) we examined (i) rate of cognitive decline (N = 164) using change in mini-mental state examination (MMSE) score, (ii) rate of whole brain atrophy (N = 149), derived from serial MR imaging, calculated using the boundary shift integral (BSI) method. HSV-1 antibodies were assayed in baseline sera collected from 2009-2015. Linear mixed-effects models were used to compare outcomes by HSV-1 seropositivity and high HSV-1 IgG titres/IgM status. RESULTS: There was no association between baseline HSV-1 seropositivity and rates of cognitive decline or whole brain atrophy. Having high HSV-1 IgG titres/IgM was associated with a slightly greater decline in MMSE points per year (difference in slope - 0.365, 95% CI: -0.958 to -0.072), but not with rate of whole brain atrophy. Symptomatic mutation carriers declined fastest on both MMSE and BSI measures, however, this was not influenced by HSV-1. Among asymptomatic mutation carriers, rates of decline on MMSE and BSI were slightly greater among those who were HSV-1 seronegative. Among mutation-negative individuals, no differences were seen by HSV-1. Stratifying by APOE4 status yielded inconsistent results. INTERPRETATION: We found no evidence for a major role of HSV-1, measured by serum antibodies, in cognitive decline or whole brain atrophy among individuals at high risk of early-onset AD.

Glioblastoma-dependent differentiation and angiogenic potential of human mesenchymal stem cells in vitro.

Tumor angiogenesis is of central importance in the malignancy of glioblastoma multiforme (GBM). As previously shown, human mesenchymal stem cells (hMSC) migrate towards GBM and are incorporated into tumor microvessels. However, phenotype and function of recruited hMSC remain unclear. We evaluated the differentiation and angiogenic potential of hMSC after stimulation with glioblastoma-conditioned medium in vitro. Immunostaining with endothelial, smooth muscle cell and pericyte markers was used to analyze hMSC differentiation in different concentrations of tumor-conditioned medium (CM), and the angiogenic potential was evaluated by matrigel-based tube-formation assay (TFA). Immunofluorescence staining revealed that tumor-conditioned hMSC (CM-hMSC) expressed CD 151, VE-cadherin, desmin, α-smooth muscle actin, nestin, and nerval/glial antigen 2 (NG2) in a CM concentration-dependent manner, whereas no expression of von-Willebrand factor (vWF) and smooth myosin could be detected. These findings are indicative of GBM-dependent differentiation of hMSC into pericyte-like cells, rather than endothelial or smooth muscle cells. Furthermore, TFA of hMSC and CM-hMSC revealed CM-dependent formation of capillary-like networks, which differed substantially from those formed by human endothelial cells (HUVEC), also implying pericyte-like tube formation. These results are indicative of GBM-derived differentiation of hMSC into pericyte-like mural cells, which might contribute to the neovascularization and stabilization of tumor vessels.

Assisted Suicide in Parkinsonian Disorders.

Background: Due to the high prevalence of suicidal ideation in Parkinson's Disease (PD) and exploratory data indicating a similar prevalence in atypical Parkinsonian disorders (APD), we sought to determine the frequency of assisted suicide (AS) as well as factors driving these decisions in PD and APD. Methods: Retrospective chart analysis (2006-2012) at a Swiss Right-to-Die organization. Patients with PD and APD who completed AS were analyzed concerning disease state, symptom burden, medication, and social factors. Results: We identified 72 patients (PD = 34, PSP = 17, MSA = 17, CBS = 4; 7.2% of all AS cases), originating mainly from Germany (41.7%), Great Britain (29.2%), and the US (8.3%). Predominant symptoms at the time of application were immobility (PD/APD: 91%/97%), helplessness (63%/70%), pain (69%/19%), dysarthria (25%/32%), and dysphagia (19%/59%). APD patients generally showed a higher symptom burden and a higher frequency of diagnosed depression (8.8%/28.9%). While most patients with diagnosed depression received antidepressants (80%), other symptoms such as pain (59%) were treated less consistently. Of note, time from diagnosis to application differed greatly between PD (8.5 ± 6.8 years) and APD (1.5 ± 1.3 years, p < 0.0001). Conclusions: In our analysis, Parkinsonian disorders appeared to be overrepresented as a cause of AS considering the prevalence of these diseases. The observation that assisted suicide is sought early after initial diagnosis in APD implies the need for early comprehensive psychological support of these patients and their relatives.

Low-degree trisomy 21 mosaicism promotes early-onset Alzheimer disease.

Trisomy-21 mosaicism (mT21) with subclinical intellectual development disorder or physical phenotype has very rarely been associated with early-onset cognitive decline. Notably, early-onset Alzheimer's disease (EOAD) patients' family histories frequently suggest genetic causes other than autosomal-dominant APP/PSEN-1/2 mutations. We present an EOAD patient in his late fifties newly diagnosed with low-degree mT21 (13%/21% blood lymphocytes/ectodermal cells). We applied fluorescence in-situ hybridization to confirm a diagnosis of mT21. Multimodal positron-emission-tomography applying 18F-fluodesoxyglucose (metabolism), 18F-florbetaben (amyloid-ß deposits) and 18F-PI-2620 (tau-deposits) tracers was used to confirm a diagnosis of EOAD according to the ATN-criteria of AD. Initial PET-studies revealed marked cerebral amyloid-ß- and tau-pathology and parietotemporal hypometabolism, confirming EOAD according to the ATN-criteria of AD. A marked cognitive decline was accompanied by an increase in tau pathology in follow-up studies. This is the first case demonstrating that a low-degree APP gene-dose increase suffices to cause EOAD with prominent amyloid-ß/tau pathology.

Binding of Metal-Ion-Induced Tau Oligomers to Lipid Surfaces Is Enhanced by GSK-3ß-Mediated Phosphorylation.

While fibrillar deposits of hyperphosphorylated protein tau are a key hallmark of several neurodegenerative diseases such as Alzheimer's disease, small oligomers have been speculated to be the key toxic aggregate species. Trivalent metal ions were shown to promote tau oligomer formation in vitro. However, little is known about potential intercellular spreading mechanisms or toxic modes of action of such oligomers. We investigated interactions of tau monomers and Fe3+/Al3+-induced oligomers with small unilamellar vesicles derived from 1-palmitoyl-2-oleoyl-phosphatidylcholine (neutral, liquid-crystalline phase) and dipalmitoyl-phosphatidylcholine (neutral, gel-phase). We further evaluated the influence of glycogen synthase kinase 3ß (GSK-3ß)-mediated tau phosphorylation applying the single-particle fluorescence spectroscopy techniques fluorescence correlation spectroscopy, fluorescence intensity distribution analysis, and scanning for intensely fluorescent targets. In these experiments, no binding to neutral lipid surfaces was observed for tau monomers. In contrast, metal-ion-induced tau oligomers showed a gain of function in binding to neutral lipid surfaces. Of note, tau phosphorylation by GSK-3ß increased both oligomer formation and membrane affinity of the resulting oligomers. In conclusion, our data imply a pathological gain of function of metal-ion-induced oligomers of hyperphosphorylated tau, enabling membrane binding irrespective of surface charge even at nanomolar protein concentrations.

Gait analysis in PSP and NPH: Dual-task conditions make the difference.

OBJECTIVE: To test whether quantitative gait analysis of gait under single- and dual-task conditions can be used for a differential diagnosis of progressive supranuclear palsy (PSP) and idiopathic normal-pressure hydrocephalus (iNPH). METHODS: In this cross-sectional study, temporal and spatial gait parameters were analyzed in 38 patients with PSP (Neurological Disorders and Stroke and Society for Progressive Supranuclear Palsy diagnostic criteria), 27 patients with iNPH (international iNPH guidelines), and 38 healthy controls. A pressure-sensitive carpet was used to examine gait under 5 conditions: single task (preferred, slow, and maximal speed), cognitive dual task (walking with serial 7 subtractions), and motor dual task (walking while carrying a tray). RESULTS: The main results were as follows. First, both patients with PSP and those with iNPH exhibited significant gait dysfunction, which was worse in patients with iNPH with a more broad-based gait (p < 0.001). Second, stride time variability was increased in both patient groups, more pronounced in PSP (p = 0.009). Third, cognitive dual task led to a greater reduction of gait velocity in PSP (PSP 34.4% vs iNPH 16.9%, p = 0.002). Motor dual task revealed a dissociation of gait performance: patients with PSP considerably worsened, but patients with iNPH tended to improve. CONCLUSION: Patients with PSP seem to be more sensitive to dual-task perturbations than patients with iNPH. An increased step width and anisotropy of the effect of dual-task conditions (cognitive vs motor) seem to be good diagnostic tools for iNPH.

Alzheimer's disease in Down syndrome: An overlooked population for prevention trials.

The discovery that adults with Down syndrome (DS) have neuropathological features identical to individuals with sporadic Alzheimer's disease (AD) played a key role in the identification of the amyloid precursor protein gene on chromosome 21 and resulted in the amyloid cascade hypothesis. Individuals with DS have a lifetime risk for dementia in excess of 90%, and DS is now acknowledged to be a genetic form of AD similar to rare autosomal-dominant causes. Just as DS put the spotlight on amyloid precursor protein mutations, it is also likely to inform us of the impact of manipulating the amyloid pathway on treatment outcomes in AD. Ironically, however, individuals with DS are usually excluded from AD trials. This review will discuss primary and secondary prevention trials for AD in DS and the potential barriers and solutions to such trials and describe the Europe-wide Horizon21 Consortium to establish a DS-AD prevention clinical trials network.

PROSPERA: a randomized, controlled trial evaluating rasagiline in progressive supranuclear palsy.

To date, pharmacological treatment options for progressive supranuclear palsy (PSP), a neurodegenerative tauopathy, are limited. The MAO-B inhibitor rasagiline has shown neuroprotective effects in preclinical models of neurodegeneration. To evaluate the safety, tolerability and therapeutic effect of rasagiline on symptom progression in PSP. In this 1-year randomized, double-blind, placebo-controlled trial, 44 patients fulfilling the NINDS-PSP criteria were randomized to 1 mg/d rasagiline or placebo. The combined primary endpoint included symptom progression as measured by the PSP rating scale (PSP-RS) and the requirement of L-dopa rescue medication. Secondary endpoints included Schwab and England Activities of Daily Living (SEADL), Montgomery-Åsberg Depression Rating Scale, Mini Mental State Examination, Frontal Assessment Battery and posturographic measurements. Of the 44 patients randomized, 26 completed the trial per protocol. Rasagiline was well tolerated, with a slight increase of known side effects (hallucinations, ventricular extrasystoles). No effect on the primary endpoint (p = 0.496) was detected. Symptom progression averaged at 11.2 (rasagiline) and 10.8 (placebo) points per year (ΔPSP-RS). No difference was seen in SEADL, depression, cognitive function, frontal executive function and posturographic measurements. Post hoc analyses of PSP-RS subdomains indicate a potential beneficial effect in the "limb motor" subdomain, whereas performance appeared lower in the "mentation" and "history" subdomains in the treatment group. While rasagiline is well tolerated in PSP, a beneficial effect on overall symptom progression was not detected. Post hoc analyses suggest the implementation of more specific endpoints in future studies.