Genetic variants in the triggering receptor expressed on myeloid cells 2 (TREM2) have been linked to Nasu-Hakola disease, Alzheimer's disease (AD), Parkinson's disease, amyotrophic lateral sclerosis, ...frontotemporal dementia (FTD), and FTD-like syndrome without bone involvement. TREM2 is an innate immune receptor preferentially expressed by microglia and is involved in inflammation and phagocytosis. Whether and how TREM2 missense mutations affect TREM2 function is unclear. We report that missense mutations associated with FTD and FTD-like syndrome reduce TREM2 maturation, abolish shedding by ADAM proteases, and impair the phagocytic activity of TREM2-expressing cells. As a consequence of reduced shedding, TREM2 is virtually absent in the cerebrospinal fluid (CSF) and plasma of a patient with FTD-like syndrome. A decrease in soluble TREM2 was also observed in the CSF of patients with AD and FTD, further suggesting that reduced TREM2 function may contribute to increased risk for two neurodegenerative disorders.
Objective
To estimate the prevalence of amyloid positivity, defined by positron emission tomography (PET)/cerebrospinal fluid (CSF) biomarkers and/or neuropathological examination, in primary ...progressive aphasia (PPA) variants.
Methods
We conducted a meta‐analysis with individual participant data from 1,251 patients diagnosed with PPA (including logopenic lvPPA, n = 443, nonfluent nfvPPA, n = 333, semantic svPPA, n = 401, and mixed/unclassifiable n = 74 variants of PPA) from 36 centers, with a measure of amyloid‐β pathology (CSF n = 600, PET n = 366, and/or autopsy n = 378) available. The estimated prevalence of amyloid positivity according to PPA variant, age, and apolipoprotein E (ApoE) ε4 status was determined using generalized estimating equation models.
Results
Amyloid‐β positivity was more prevalent in lvPPA (86%) than in nfvPPA (20%) or svPPA (16%; p < 0.001). Prevalence of amyloid‐β positivity increased with age in nfvPPA (from 10% at age 50 years to 27% at age 80 years, p < 0.01) and svPPA (from 6% at age 50 years to 32% at age 80 years, p < 0.001), but not in lvPPA (p = 0.94). Across PPA variants, ApoE ε4 carriers were more often amyloid‐β positive (58.0%) than noncarriers (35.0%, p < 0.001). Autopsy data revealed Alzheimer disease pathology as the most common pathologic diagnosis in lvPPA (76%), frontotemporal lobar degeneration–TDP‐43 in svPPA (80%), and frontotemporal lobar degeneration–TDP‐43/tau in nfvPPA (64%).
Interpretation
This study shows that the current PPA classification system helps to predict underlying pathology across different cohorts and clinical settings, and suggests that age and ApoE genotype should be considered when interpreting amyloid‐β biomarkers in PPA patients. Ann Neurol 2018;84:737–748
Objective
To identify a novel biochemical marker that precedes clinical symptoms in Alzheimer disease (AD).
Methods
Using quantitative polymerase chain reaction techniques, we measured circulating ...cell‐free mitochondrial DNA (mtDNA) in cerebrospinal fluid (CSF) from study participants, selected from a cohort of 282 subjects, who were classified according to their concentrations of amyloid β1–42, total tau, and phosphorylated tau and by the presence or absence of dementia, into asymptomatic subjects at risk of AD, symptomatic patients diagnosed with sporadic AD, presymptomatic subjects carrying pathogenic PSEN1 mutations, and patients diagnosed with frontotemporal lobar degeneration (FTLD). We performed equivalent studies in a separate validation cohort of sporadic AD and FTLD patients. In addition, we measured mtDNA copy number in cultured cortical neurons from mutant amyloid precursor protein/presenilin1 (APP/PS1) transgenic mice.
Results
Asymptomatic patients at risk of AD and symptomatic AD patients, but not FTLD patients, exhibit a significant decrease in circulating cell‐free mtDNA in the CSF. These observations were confirmed in the validation cohort. In addition, presymptomatic subjects carrying pathogenic PSEN1 gene mutations show low mtDNA content in CSF before the appearance of AD‐related biomarkers in CSF. Moreover, mtDNA content in CSF discriminates with high sensitivity and specificity AD patients from either controls or patients with FTLD. Furthermore, cultured cortical neurons from APP/PS1 transgenic mice have fewer mtDNA copies before the appearance of altered synaptic markers.
Interpretation
Low content of mtDNA in CSF may be a novel biomarker for the early detection of preclinical AD. These findings support the hypothesis that mtDNA depletion is a characteristic pathophysiological factor of neurodegeneration in AD. Ann Neurol 2013;74:655–668
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the coronavirus disease 2019 (COVID-19) pandemic. In addition to severe respiratory symptoms, there are a growing number ...of reports showing a wide range of CNS complications in patients with COVID-19. Here, we review the literature on these complications, ranging from nonspecific symptoms to necrotizing encephalopathies, encephalitis, myelitis, encephalomyelitis, endotheliitis, and stroke. We postulate that there are several different mechanisms involved in COVID-19-associated CNS dysfunction, particularly activation of inflammatory and thrombotic pathways and, in a few patients, a direct viral effect on the endothelium and the parenchyma. Last, critically ill patients frequently present with protracted cognitive dysfunction in the setting of septic encephalopathy likely due to multifactorial mechanisms. Further studies are needed to clarify the relative contribution of each of these mechanisms, but available data suggest that CNS complications in COVID-19 are rare and probably not directly caused by the virus.
Anti‐IgLON5 disease is a neurological disorder characterized by autoantibodies against IgLON5 and pathological evidence of neuronal‐specific tau accumulation. Here, we report that patients' IgLON5 ...IgG, but not other cell‐surface antibodies, disrupt the cytoskeletal organization in cultured rat hippocampal neurons, resulting in dystrophic neurites and axonal swelling. Adsorption of IgLON5 IgG with HEK293 cells expressing IgLON5 abrogated the indicated cytoskeletal changes. These findings, along with an increase of levels of neurofilaments in patients' cerebrospinal fluid, suggest that IgLON5 IgG, unlike other cell‐surface antibodies, disrupts neuronal cytoskeleton maintenance, providing a link between autoimmunity and neurodegeneration. ANN NEUROL 2020;88:1023–1027
Quantitative in vivo measurement of brain amyloid burden is important for both research and clinical purposes. However, the existence of multiple imaging tracers presents challenges to the ...interpretation of such measurements. This study presents a direct comparison of Pittsburgh compound B–based and florbetapir-based amyloid imaging in the same participants from two independent cohorts using a crossover design.
Pittsburgh compound B and florbetapir amyloid PET imaging data from three different cohorts were analyzed using previously established pipelines to obtain global amyloid burden measurements. These measurements were converted to the Centiloid scale to allow fair comparison between the two tracers. The mean and inter-individual variability of the two tracers were compared using multivariate linear models both cross-sectionally and longitudinally.
Global amyloid burden measured using the two tracers were strongly correlated in both cohorts. However, higher variability was observed when florbetapir was used as the imaging tracer. The variability may be partially caused by white matter signal as partial volume correction reduces the variability and improves the correlations between the two tracers. Amyloid burden measured using both tracers was found to be in association with clinical and psychometric measurements. Longitudinal comparison of the two tracers was also performed in similar but separate cohorts whose baseline amyloid load was considered elevated (i.e., amyloid positive). No significant difference was detected in the average annualized rate of change measurements made with these two tracers.
Although the amyloid burden measurements were quite similar using these two tracers as expected, difference was observable even after conversion into the Centiloid scale. Further investigation is warranted to identify optimal strategies to harmonize amyloid imaging data acquired using different tracers.
...randomised controlled trials (RCTs) of interventions to prevent cognitive decline, dementia, or Alzheimer's disease have shown negative or very modest results.2 In the absence of a gold standard, ...methods in RCTs to prevent cognitive decline are heterogeneous in timing, duration, type of intervention (eg, single-target vs multi-target or pharmacological vs non-pharmacological), population enrichment strategies (based on age, genetic profile, biomarker characterisation, or lifestyle and comorbidities), disease progression modelling, and outcome measures (sensitive vs clinically meaningful outcomes).2 In The Lancet Neurology, Daniel K Burns and colleagues3 report the main results of TOMMORROW, a trial aimed to evaluate the safety and efficacy of low-dose pioglitazone, an insulin-sensitising agent used in the treatment of type 2 diabetes, to delay cognitive impairment onset in a group of pre-selected non-diabetic participants at high risk of developing mild cognitive impairment. ...pioglitazone did not delay the onset of mild cognitive impairment compared with placebo, nor did cognitive or functional changes from baseline differ between the treatment and placebo groups. In a huge research effort in 59 sites, 24 136 potential participants were screened, 3061 were categorised as at high risk and randomised, and 433 participants at low risk were allocated to the placebo arm.3 During the study period, fewer participants than estimated converted to mild cognitive impairment, suggesting that the model used for disease progression (which was based on longitudinal cohort data) had a limited capacity to predict outcomes in participants assigned to placebo.6,7 Logistical regression analysis of the target population showed that enriched inclusion of participants at high risk was driven by the combination of age and APOE status, and TOMM40 genotype did not contribute to improved risk prediction.
Sex differences in early‐onset Alzheimer's disease Contador, José; Pérez‐Millan, Agnès; Guillén, Nuria ...
European journal of neurology,
December 2022, 2022-12-00, 20221201, Letnik:
29, Številka:
12
Journal Article
Recenzirano
Background and purpose
Sex is believed to drive heterogeneity in Alzheimer's disease (AD), although evidence in early‐onset AD (EOAD; <65 years) is scarce.
Methods
We included 62 EOAD patients and 44 ...healthy controls (HCs) with core AD cerebrospinal fluid (CSF) biomarkers, neurofilament light chain levels, neuropsychological assessment, and 3‐T magnetic resonance imaging. We measured cortical thickness (CTh) and hippocampal subfield volumes (HpS) using FreeSurfer. Adjusted linear models were used to analyze sex‐differences and the relationship between atrophy and cognition.
Results
Compared to same‐sex HCs, female EOAD subjects showed greater cognitive impairment and broader atrophy burden than male EOAD subjects. In a direct female‐EOAD versus male‐EOAD comparison, there were slight differences in temporal CTh, with no differences in cognition or HpS. CSF tau levels were higher in female EOAD than in male EOAD subjects. Greater atrophy was associated with worse cognition in female EOAD subjects.
Conclusions
At diagnosis, there are sex differences in the pattern of cognitive impairment, atrophy burden, and CSF tau in EOAD, suggesting there is an influence of sex on pathology spreading and susceptibility to the disease in EOAD.
Objective
To evaluate cerebrospinal fluid (CSF) and serum neurofilament light chain (NfL) levels in genetic frontotemporal dementia (FTD) as a potential biomarker in the presymptomatic stage and ...during the conversion into the symptomatic stage. Additionally, to correlate NfL levels to clinical and neuroimaging parameters.
Methods
In this multicenter case–control study, we investigated CSF NfL in 174 subjects (48 controls, 40 presymptomatic carriers and 86 patients with microtubule‐associated protein tau (MAPT), progranulin (GRN), and chromosome 9 open reading frame 72 (C9orf72) mutations), and serum NfL in 118 subjects (39 controls, 44 presymptomatic carriers, 35 patients). In 55 subjects both CSF and serum was determined. In two subjects CSF was available before and after symptom onset (converters). Additionally, NfL levels were correlated with clinical parameters, survival, and regional brain atrophy.
Results
CSF NfL levels in patients (median 6762 pg/mL, interquartile range 3186–9309 pg/mL) were strongly elevated compared with presymptomatic carriers (804 pg/mL, 627–1173 pg/mL, P < 0.001), resulting in a good diagnostic performance to discriminate both groups. Serum NfL correlated highly with CSF NfL (rs = 0.87, P < 0.001) and was similarly elevated in patients. Longitudinal samples in the converters showed a three‐ to fourfold increase in CSF NfL after disease onset. Additionally, NfL levels in patients correlated with disease severity, brain atrophy, annualized brain atrophy rate and survival.
Interpretation
NfL in both serum and CSF has the potential to serve as a biomarker for clinical disease onset and has a prognostic value in genetic FTD.
Introduction
Apathy adversely affects prognosis and survival of patients with frontotemporal dementia (FTD). We test whether apathy develops in presymptomatic genetic FTD, and is associated with ...cognitive decline and brain atrophy.
Methods
Presymptomatic carriers of MAPT, GRN or C9orf72 mutations (N = 304), and relatives without mutations (N = 296) underwent clinical assessments and MRI at baseline, and annually for 2 years. Longitudinal changes in apathy, cognition, gray matter volumes, and their relationships were analyzed with latent growth curve modeling.
Results
Apathy severity increased over time in presymptomatic carriers, but not in non‐carriers. In presymptomatic carriers, baseline apathy predicted cognitive decline over two years, but not vice versa. Apathy progression was associated with baseline low gray matter volume in frontal and cingulate regions.
Discussion
Apathy is an early marker of FTD‐related changes and predicts a subsequent subclinical deterioration of cognition before dementia onset. Apathy may be a modifiable factor in those at risk of FTD.
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