| 1. |
- Ewers, Michael, et al.
(author)
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Body mass index is associated with biological CSF markers of core brain pathology of Alzheimer's disease
- 2012
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In: Neurobiology of Aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 33:8, s. 1599-1608
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Journal article (peer-reviewed)abstract
- Weight changes are common in aging and Alzheimer's disease (AD) and postmortem findings suggest a relation between lower body mass index (BMI) and increased AD brain pathology. In the current multicenter study, we tested whether lower BMI is associated with higher core AD brain pathology as assessed by cerebrospinal fluid (CSF)-based biological markers of AD in 751 living subjects: 308 patients with AD, 296 subjects with amnestic mild cognitive impairment (MCI), and 147 elderly healthy controls (HC). Based upon a priori cutoff values on CSF concentration of total tau and beta-amyloid (A beta(1-42)), subjects were binarized into a group with abnormal CSF biomarker signature (CSF+) and those without (CSF-). Results showed that BMI was significantly lower in the CSF+ when compared with the CSF- group (F = 27.7, df = 746, p < 0.001). There was no interaction between CSF signature and diagnosis or apolipoprotein E (ApoE) genotype. In conclusion, lower BMI is indicative of AD pathology as assessed with CSF-based biomarkers in demented and nondemented elderly subjects. Published by Elsevier Inc.
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| 2. |
- Coley, Nicola, et al.
(author)
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Plasma p-tau181 as an outcome and predictor of multidomain intervention effects: a secondary analysis of a randomised, controlled, dementia prevention trial
- 2024
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In: The Lancet Healthy Longevity. - 2666-7568. ; 5:2
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Journal article (peer-reviewed)abstract
- Background: It is unknown whether multidomain interventions, which might preserve late-life cognition, affect Alzheimer's disease pathology. Previous studies measured cerebrospinal fluid and imaging Alzheimer's disease biomarkers in small subsamples of multidomain trial participants. Newly developed assays enable the measurement of blood-based Alzheimer's disease biomarkers in larger samples. We aimed to assess whether plasma tau phosphorylated at threonine 181 (p-tau181) was able to detect or predict 3-year multidomain intervention effects. Methods: This is a secondary analysis of the randomised, controlled, Multidomain Alzheimer Prevention Trial (MAPT) testing a 3-year multidomain intervention, omega-3 fatty acid supplementation, or both versus placebo, in individuals aged 70 years and older in 13 memory centres in France and Monaco. Plasma p-tau181 was measured in stored blood samples in a subsample of 527 participants on an intention-to-treat basis. Changes in cognitive score were calculated as a composite measure using the average of Z scores for the following tests: Mini Mental State Examination orientation items, Free and Cued Selective Reminding Test (sum of free and total recall scores), category fluency, and Digit Symbol Substitution Test. Intervention effects on 3-year change in p-tau181 concentration were estimated by use of a linear mixed model with centre-specific random intercepts. Findings: Recruitment took place between May 30, 2008, and Feb 24, 2011. Median baseline plasma p-tau181 was 8·8 pg/mL (IQR 6·7–11·9) in the total sample, and significantly higher in older individuals, men, APOE ε4 carriers, and participants with renal dysfunction or a positive PET amyloid scan. During 3-year follow-up, individuals with raised baseline p-tau181 underwent greater cognitive decline (eg, mean difference in 3-year change on the composite cognitive score between control group participants with normal and abnormal baseline levels of p-tau was −0·34 [effect size −0·52; 95% CI −0·61 to 0·07] in the fully adjusted model using a 12·4 pg/mL cutoff for abnormal baseline p-tau181), but there were no intervention effects on change in p-tau181 either in this subgroup or the total population, and no effect on cognitive change in individuals with raised baseline p-tau181 (eg, in the fully adjusted model using the 12·4 pg/mL cutoff for p-tau181 abnormality, the mean difference [95% CI] in this subgroup in 3-year decline on the composite cognitive score between the control group and the multidomain + omega-3 group, the omega-3 group, and the multidomain intervention group, was, respectively: 0·13 [−0·21 to 0·47], 0·03 [−0·30 to 0·36], and 0·10 [−0·26 to 0·46]). Surprisingly, individuals with raised baseline p-tau181 showed a decrease in p-tau181 during follow-up (eg, unadjusted mean [95% CI] 3-year change was −3·01 pg/mL (−4·45 to −1·56) in control group subjects with abnormal baseline p-tau181 [using the 12·4 pg/mL abnormal p-tau cutoff]). Interpretation: Our results support the utility of p-tau181 as a prognostic biomarker, but it did not predict or detect intervention effects in this study. Further investigation of its usefulness as a prevention trial outcome measure is required.
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| 3. |
- Dubois, Bruno, et al.
(author)
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Advancing research diagnostic criteria for Alzheimer's disease: the IWG-2 criteria.
- 2014
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In: Lancet neurology. - 1474-4465. ; 13:6, s. 614-29
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Research review (peer-reviewed)abstract
- In the past 8 years, both the International Working Group (IWG) and the US National Institute on Aging-Alzheimer's Association have contributed criteria for the diagnosis of Alzheimer's disease (AD) that better define clinical phenotypes and integrate biomarkers into the diagnostic process, covering the full staging of the disease. This Position Paper considers the strengths and limitations of the IWG research diagnostic criteria and proposes advances to improve the diagnostic framework. On the basis of these refinements, the diagnosis of AD can be simplified, requiring the presence of an appropriate clinical AD phenotype (typical or atypical) and a pathophysiological biomarker consistent with the presence of Alzheimer's pathology. We propose that downstream topographical biomarkers of the disease, such as volumetric MRI and fluorodeoxyglucose PET, might better serve in the measurement and monitoring of the course of disease. This paper also elaborates on the specific diagnostic criteria for atypical forms of AD, for mixed AD, and for the preclinical states of AD.
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| 4. |
- Beecham, Ashley H, et al.
(author)
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Analysis of immune-related loci identifies 48 new susceptibility variants for multiple sclerosis.
- 2013
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In: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:11, s. 1353-60
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Journal article (peer-reviewed)abstract
- Using the ImmunoChip custom genotyping array, we analyzed 14,498 subjects with multiple sclerosis and 24,091 healthy controls for 161,311 autosomal variants and identified 135 potentially associated regions (P < 1.0 × 10(-4)). In a replication phase, we combined these data with previous genome-wide association study (GWAS) data from an independent 14,802 subjects with multiple sclerosis and 26,703 healthy controls. In these 80,094 individuals of European ancestry, we identified 48 new susceptibility variants (P < 5.0 × 10(-8)), 3 of which we found after conditioning on previously identified variants. Thus, there are now 110 established multiple sclerosis risk variants at 103 discrete loci outside of the major histocompatibility complex. With high-resolution Bayesian fine mapping, we identified five regions where one variant accounted for more than 50% of the posterior probability of association. This study enhances the catalog of multiple sclerosis risk variants and illustrates the value of fine mapping in the resolution of GWAS signals.
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| 5. |
- Bollack, Ariane, et al.
(author)
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Investigating reliable amyloid accumulation in Centiloids : Results from the AMYPAD Prognostic and Natural History Study
- 2024
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In: Alzheimer's and Dementia. - 1552-5260 .- 1552-5279. ; 20:5, s. 3429-3441
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Journal article (peer-reviewed)abstract
- INTRODUCTION: To support clinical trial designs focused on early interventions, our study determined reliable early amyloid-β (Aβ) accumulation based on Centiloids (CL) in pre-dementia populations. METHODS: A total of 1032 participants from the Amyloid Imaging to Prevent Alzheimer's Disease–Prognostic and Natural History Study (AMYPAD-PNHS) and Insight46 who underwent [18F]flutemetamol, [18F]florbetaben or [18F]florbetapir amyloid-PET were included. A normative strategy was used to define reliable accumulation by estimating the 95th percentile of longitudinal measurements in sub-populations (NPNHS = 101/750, NInsight46 = 35/382) expected to remain stable over time. The baseline CL threshold that optimally predicts future accumulation was investigated using precision-recall analyses. Accumulation rates were examined using linear mixed-effect models. RESULTS: Reliable accumulation in the PNHS was estimated to occur at >3.0 CL/year. Baseline CL of 16 [12,19] best predicted future Aβ-accumulators. Rates of amyloid accumulation were tracer-independent, lower for APOE ε4 non-carriers, and for subjects with higher levels of education. DISCUSSION: Our results support a 12–20 CL window for inclusion into early secondary prevention studies. Reliable accumulation definition warrants further investigations.
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| 6. |
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| 7. |
- Hampel, Harald, et al.
(author)
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Advances in the therapy of Alzheimer's disease : targeting amyloid beta and tau and perspectives for the future
- 2015
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In: Expert Review of Neurotherapeutics. - : Informa UK Limited. - 1473-7175 .- 1744-8360. ; 15:1, s. 83-105
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Research review (peer-reviewed)abstract
- Worldwide multidisciplinary translational research has led to a growing knowledge of the genetics and molecular pathogenesis of Alzheimer's disease (AD) indicating that pathophysiological brain alterations occur decades before clinical signs and symptoms of cognitive decline can be diagnosed. Consequently, therapeutic concepts and targets have been increasingly focused on early-stage illness before the onset of dementia; and distinct classes of compounds are now being tested in clinical trials. At present, there is a growing consensus that therapeutic progress in AD delaying disease progression would significantly decrease the expanding global burden. The evolving hypothesis- and evidence-based generation of new diagnostic research criteria for early-stage AD has positively impacted the development of clinical trial designs and the characterization of earlier and more specific target populations for trials in prodromal as well as in pre- and asymptomatic at-risk stages of AD.
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| 8. |
- Jansen, Willemijn J, et al.
(author)
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Prevalence Estimates of Amyloid Abnormality Across the Alzheimer Disease Clinical Spectrum.
- 2022
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In: JAMA neurology. - : American Medical Association (AMA). - 2168-6157 .- 2168-6149. ; 79:3, s. 228-243
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Journal article (peer-reviewed)abstract
- One characteristic histopathological event in Alzheimer disease (AD) is cerebral amyloid aggregation, which can be detected by biomarkers in cerebrospinal fluid (CSF) and on positron emission tomography (PET) scans. Prevalence estimates of amyloid pathology are important for health care planning and clinical trial design.To estimate the prevalence of amyloid abnormality in persons with normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia and to examine the potential implications of cutoff methods, biomarker modality (CSF or PET), age, sex, APOE genotype, educational level, geographical region, and dementia severity for these estimates.This cross-sectional, individual-participant pooled study included participants from 85 Amyloid Biomarker Study cohorts. Data collection was performed from January 1, 2013, to December 31, 2020. Participants had normal cognition, subjective cognitive decline, mild cognitive impairment, or clinical AD dementia. Normal cognition and subjective cognitive decline were defined by normal scores on cognitive tests, with the presence of cognitive complaints defining subjective cognitive decline. Mild cognitive impairment and clinical AD dementia were diagnosed according to published criteria.Alzheimer disease biomarkers detected on PET or in CSF.Amyloid measurements were dichotomized as normal or abnormal using cohort-provided cutoffs for CSF or PET or by visual reading for PET. Adjusted data-driven cutoffs for abnormal amyloid were calculated using gaussian mixture modeling. Prevalence of amyloid abnormality was estimated according to age, sex, cognitive status, biomarker modality, APOE carrier status, educational level, geographical location, and dementia severity using generalized estimating equations.Among the 19097 participants (mean [SD] age, 69.1 [9.8] years; 10148 women [53.1%]) included, 10139 (53.1%) underwent an amyloid PET scan and 8958 (46.9%) had an amyloid CSF measurement. Using cohort-provided cutoffs, amyloid abnormality prevalences were similar to 2015 estimates for individuals without dementia and were similar across PET- and CSF-based estimates (24%; 95% CI, 21%-28%) in participants with normal cognition, 27% (95% CI, 21%-33%) in participants with subjective cognitive decline, and 51% (95% CI, 46%-56%) in participants with mild cognitive impairment, whereas for clinical AD dementia the estimates were higher for PET than CSF (87% vs 79%; mean difference, 8%; 95% CI, 0%-16%; P=.04). Gaussian mixture modeling-based cutoffs for amyloid measures on PET scans were similar to cohort-provided cutoffs and were not adjusted. Adjusted CSF cutoffs resulted in a 10% higher amyloid abnormality prevalence than PET-based estimates in persons with normal cognition (mean difference, 9%; 95% CI, 3%-15%; P=.004), subjective cognitive decline (9%; 95% CI, 3%-15%; P=.005), and mild cognitive impairment (10%; 95% CI, 3%-17%; P=.004), whereas the estimates were comparable in persons with clinical AD dementia (mean difference, 4%; 95% CI, -2% to 9%; P=.18).This study found that CSF-based estimates using adjusted data-driven cutoffs were up to 10% higher than PET-based estimates in people without dementia, whereas the results were similar among people with dementia. This finding suggests that preclinical and prodromal AD may be more prevalent than previously estimated, which has important implications for clinical trial recruitment strategies and health care planning policies.
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| 9. |
- Larochelle, Jean, et al.
(author)
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Effect of nitisinone (NTBC) treatment on the clinical course of hepatorenal tyrosinemia in Québec.
- 2012
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In: Molecular genetics and metabolism. - : Elsevier BV. - 1096-7206 .- 1096-7192. ; 107:1-2, s. 49-54
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Journal article (peer-reviewed)abstract
- Hepatorenal tyrosinemia (HT1, fumarylacetoacetate hydrolase deficiency, MIM 276700) can cause severe hepatic, renal and peripheral nerve damage. In Québec, HT1 is frequent and neonatal HT1 screening is practiced. Nitisinone (NTBC, Orfadin ®) inhibits tyrosine degradation prior to the formation of toxic metabolites like succinylacetone and has been offered to HT1 patients in Québec since 1994.
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| 10. |
- Baldacci, Filippo, et al.
(author)
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Age and sex impact plasma NFL and t-Tau trajectories in individuals with subjective memory complaints: a 3-year follow-up study.
- 2020
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In: Alzheimer's research & therapy. - : Springer Science and Business Media LLC. - 1758-9193. ; 12:1
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Journal article (peer-reviewed)abstract
- Plasma neurofilament light (NFL) and total Tau (t-Tau) proteins are candidate biomarkers for early stages of Alzheimer's disease (AD). The impact of biological factors on their plasma concentrations in individuals with subjective memory complaints (SMC) has been poorly explored. We longitudinally investigate the effect of sex, age, APOE ε4 allele, comorbidities, brain amyloid-β (Aβ) burden, and cognitive scores on plasma NFL and t-Tau concentrations in cognitively healthy individuals with SMC, a condition associated with AD development.Three hundred sixteen and 79 individuals, respectively, have baseline and three-time point assessments (at baseline, 1-year, and 3-year follow-up) of the two biomarkers. Plasma biomarkers were measured with an ultrasensitive assay in a mono-center cohort (INSIGHT-preAD study).We show an effect of age on plasma NFL, with women having a higher increase of plasma t-Tau concentrations compared to men, over time. The APOE ε4 allele does not affect the biomarker concentrations while plasma vitamin B12 deficiency is associated with higher plasma t-Tau concentrations. Both biomarkers are correlated and increase over time. Baseline NFL is related to the rate of Aβ deposition at 2-year follow-up in the left-posterior cingulate and the inferior parietal gyri. Baseline plasma NFL and the rate of change of plasma t-Tau are inversely associated with cognitive score.We find that plasma NFL and t-Tau longitudinal trajectories are affected by age and female sex, respectively, in SMC individuals. Exploring the influence of biological variables on AD biomarkers is crucial for their clinical validation in blood.
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