Plasma neuregulin 1 as a synaptic biomarker in Alzheimer's disease: a discovery cohort study

BACKGROUND: Synaptic dysfunction is an early core feature of Alzheimer's disease (AD), closely associated with cognitive symptoms. Neuregulin 1 (NRG1) is a growth and differentiation factor with a key role in the development and maintenance of synaptic transmission. Previous reports have shown that changes in cerebrospinal fluid (CSF) NRG1 concentration are associated with cognitive status and biomarker evidence of AD pathology. Plasma biomarkers reflecting synaptic impairment would be of great clinical interest. OBJECTIVE: To measure plasma NRG1 concentration in AD patients in comparison with other neurodegenerative disorders and neurological controls (NC) and to study its association with cerebrospinal fluid (CSF) core AD and synaptic biomarkers. METHODS: This retrospective study enrolled 127 participants including patients with AD at mild cognitive impairment stage (AD-MCI, n = 27) and at dementia stage (n = 35), non-AD dementia (n = 26, Aβ-negative), non-AD MCI (n = 19), and neurological controls (n=20). Plasma and CSF NRG1, as well as CSF core AD biomarkers (Aβ 42/Aβ 40 ratio, phospho-tau, and total tau), were measured using ELISA. CSF synaptic markers were measured using ELISA for GAP-43 and neurogranin and through immunoprecipitation mass spectrometry for SNAP-25. RESULTS: Plasma NRG1 concentration was higher in AD-MCI and AD dementia patients compared with neurological controls (respectively P = 0.005 and P < 0.001). Plasma NRG1 differentiated AD MCI patients from neurological controls with an area under the curve of 88.3%, and AD dementia patients from NC with an area under the curve of 87.3%. Plasma NRG1 correlated with CSF NRG1 (β = 0.372, P = 0.0056, adjusted on age and sex). Plasma NRG1 was associated with AD CSF core biomarkers in the whole cohort and in Aβ-positive patients (β = -0.197-0.423). Plasma NRG1 correlated with CSF GAP-43, neurogranin, and SNAP-25 (β = 0.278-0.355). Plasma NRG1 concentration correlated inversely with MMSE in the whole cohort and in Aβ-positive patients (all, β = -0.188, P = 0.038; Aβ+: β = -0.255, P = 0.038). CONCLUSION: Plasma NRG1 concentration is increased in AD patients and correlates with CSF core AD and synaptic biomarkers and cognitive status. Thus, plasma NRG1 is a promising non-invasive biomarker to monitor synaptic impairment in AD

Vitamin D Status, Insulin Resistance, Leptin-To-Adiponectin Ratio in Adolescents: Results of a 1-Year Lifestyle Intervention

AIM: We aimed to study the relationships between circulating 25-hydroxyvitamin D [25(OH)D], insulin resistance and leptin-to-adiponectin (L/A) ratio in Guadeloupean children and adolescents and to analyse the changes in 25(OH)D levels after a 1-year lifestyle intervention program.METHODS: 25(OH)D concentrations were measured via a chemiluminescence assay. Cardiometabolic risk factors, homoeostasis model assessment of insulin resistance (HOMA-IR), and adipokines were measured. The lifestyle intervention included dietary counselling, regular physical activity.RESULTS: Among 117 girls and boys (11–15 years old, 31.6% obese), 40% had vitamin D deficiency (25(OH)D levels &lt; 20 ng/mL). With linear regression models where 25(OH)D and HOMA-IR acted as independent variables and age, sex, BMI, L/A ratio as covariates, 25(OH)D was significantly associated with HOMA-IR alone (P = 0.036). HOMA-IR was also associated with BMI z-score ≥ 2, L/A ratio and an interaction term BMI z-score ≥ 2*L/A ratio (P &lt; 0.001 for all). After one year, in 78 children/adolescent, mean serum 25(OH)D increased significantly from 21.4 ± 4.9 ng/mL at baseline to 23.2 ± 6.0 after 1 year; P = 0.003 whereas BMI z-score, HOMA-IR and L/A ratio decreased significantly (P = 0.003, P &lt; 0.001 and P = 0.012; respectively).CONCLUSION: The association between 25(OH)D and HOMA-IR, independently of obesity and the high prevalence of vitamin D deficiency should be considered in order to prevent the later incidence of T2DM. A healthy lifestyle including non-sedentary and outdoor activities could be a way for improving vitamin D status

A Pragmatic, Data-Driven Method to Determine Cutoffs for CSF Biomarkers of Alzheimer Disease Based on Validation Against PET Imaging

OBJECTIVE: To elaborate a new algorithm to establish a standardized method to define cuff-offs for CSF biomarkers of Alzheimer's disease (AD) by validating the algorithm against CSF classification derived from PET imaging. METHODS: Low and high levels of CSF phosphorylated tau were first identified to establish optimal cut-offs for CSF amyloid-β peptide (Aβ) biomarkers. These Aβ cut-offs were then used to determine cut-offs for CSF tau and phosphorylated tau markers. We compared this algorithm to a reference method, based on tau and amyloid PET imaging status (ADNI study), and then applied the algorithm to 10 large clinical cohorts of patients. RESULTS: A total of 6,922 subjects with CSF biomarkers data were included (mean (SD) age: 70.6 (8.5) years, 51.0% women). In the ADNI study population (n=497), the agreement between classification based on our algorithm and one based on amyloid/tau PET imaging was high with Cohen's kappa coefficient between 0.87 and 0.99. Applying the algorithm to 10 large cohorts of patients (n=6,425), the proportion of persons with AD ranged from 25.9% to 43.5%. DISCUSSION: The proposed novel, pragmatic method to determine CSF biomarkers cut-offs for AD does not require assessment of other biomarkers or assumptions concerning the clinical diagnosis of patients. Use of this standardized algorithm is likely to reduce heterogeneity in AD classification

Genome wide association study of clinical duration and age at onset of sporadic CJD

Human prion diseases are rare, transmissible and often rapidly progressive dementias. The most common type, sporadic Creutzfeldt-Jakob disease (sCJD), is highly variable in clinical duration and age at onset. Genetic determinants of late onset or slower progression might suggest new targets for research and therapeutics. We assembled and array genotyped sCJD cases diagnosed in life or at autopsy. Clinical duration (median:4, interquartile range (IQR):2.5–9 (months)) was available in 3,773 and age at onset (median:67, IQR:61–73 (years)) in 3,767 cases. Phenotypes were successfully transformed to approximate normal distributions allowing genome-wide analysis without statistical inflation. 53 SNPs achieved genome-wide significance for the clinical duration phenotype; all of which were located at chromosome 20 (top SNP rs1799990, pvalue = 3.45x10-36, beta = 0.34 for an additive model; rs1799990, pvalue = 9.92x10-67, beta = 0.84 for a heterozygous model). Fine mapping, conditional and expression analysis suggests that the well-known non-synonymous variant at codon 129 is the obvious outstanding genome-wide determinant of clinical duration. Pathway analysis and suggestive loci are described. No genome-wide significant SNP determinants of age at onset were found, but the HS6ST3 gene was significant (pvalue = 1.93 x 10−6) in a gene-based test. We found no evidence of genome-wide genetic correlation between case-control (disease risk factors) and case-only (determinants of phenotypes) studies. Relative to other common genetic variants, PRNP codon 129 is by far the outstanding modifier of CJD survival suggesting only modest or rare variant effects at other genetic loci

Identification of novel risk loci and causal insights for sporadic Creutzfeldt-Jakob disease: a genome-wide association study

Background: Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the PRNP gene that encodes prion protein are strong risk factors for sCJD but, although the condition has similar heritability to other neurodegenerative disorders, no other genetic risk loci have been confirmed. We aimed to discover new genetic risk factors for sCJD, and their causal mechanisms. Methods: We did a genome-wide association study of sCJD in European ancestry populations (patients diagnosed with probable or definite sCJD identified at national CJD referral centres) with a two-stage study design using genotyping arrays and exome sequencing. Conditional, transcriptional, and histological analyses of implicated genes and proteins in brain tissues, and tests of the effects of risk variants on clinical phenotypes, were done using deep longitudinal clinical cohort data. Control data from healthy individuals were obtained from publicly available datasets matched for country. Findings: Samples from 5208 cases were obtained between 1990 and 2014. We found 41 genome-wide significant single nucleotide polymorphisms (SNPs) and independently replicated findings at three loci associated with sCJD risk; within PRNP (rs1799990; additive model odds ratio [OR] 1·23 [95% CI 1·17-1·30], p=2·68 × 10-15; heterozygous model p=1·01 × 10-135), STX6 (rs3747957; OR 1·16 [1·10-1·22], p=9·74 × 10-9), and GAL3ST1 (rs2267161; OR 1·18 [1·12-1·25], p=8·60 × 10-10). Follow-up analyses showed that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 are associated with increased expression of the major transcripts in disease-relevant brain regions. Interpretation: We present, to our knowledge, the first evidence of statistically robust genetic associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism as molecular causal mechanisms. Risk SNPs in STX6 are shared with progressive supranuclear palsy, a neurodegenerative disease associated with misfolding of protein tau, indicating that sCJD might share the same causal mechanisms as prion-like disorders. Funding: Medical Research Council and the UK National Institute of Health Research in part through the Biomedical Research Centre at University College London Hospitals National Health Service Foundation Trust

Plos Med

Background The ε4 allele of apolipoprotein E (APOE) gene and increasing age are two of the most important known risk factors for developing Alzheimer disease (AD). The diagnosis of AD based on clinical symptoms alone is known to have poor specificity; recently developed diagnostic criteria based on biomarkers that reflect underlying AD neuropathology allow better assessment of the strength of the associations of risk factors with AD. Accordingly, we examined the global and age-specific association between APOE genotype and AD by using the A/T/N classification, relying on the cerebrospinal fluid (CSF) levels of β-amyloid peptide (A, β-amyloid deposition), phosphorylated tau (T, pathologic tau), and total tau (N, neurodegeneration) to identify patients with AD. Methods and findings This case–control study included 1,593 white AD cases (55.4% women; mean age 72.8 [range = 44–96] years) with abnormal values of CSF biomarkers from nine European memory clinics and the American Alzheimer’s Disease Neuroimaging Initiative (ADNI) study. A total of 11,723 dementia-free controls (47.1% women; mean age 65.6 [range = 44–94] years) were drawn from two longitudinal cohort studies (Whitehall II and Three-City), in which incident cases of dementia over the follow-up were excluded from the control population. Odds ratio (OR) and population attributable fraction (PAF) for AD associated with APOE genotypes were determined, overall and by 5-year age categories. In total, 63.4% of patients with AD and 22.6% of population controls carried at least one APOE ε4 allele. Compared with non-ε4 carriers, heterozygous ε4 carriers had a 4.6 (95% confidence interval 4.1–5.2; p < 0.001) and ε4/ε4 homozygotes a 25.4 (20.4–31.2; p < 0.001) higher OR of AD in unadjusted analysis. This association was modified by age (p for interaction < 0.001). The PAF associated with carrying at least one ε4 allele was greatest in the 65–70 age group (69.7%) and weaker before 55 years (14.2%) and after 85 years (22.6%). The protective effect of APOE ε2 allele for AD was unaffected by age. Main study limitations are that analyses were based on white individuals and AD cases were drawn from memory centers, which may not be representative of the general population of patients with AD. Conclusions In this study, we found that AD diagnosis based on biomarkers was associated with APOE ε4 carrier status, with a higher OR than previously reported from studies based on only clinical AD criteria. This association differs according to age, with the strongest effect at 65–70 years. These findings highlight the need for early interventions for dementia prevention to mitigate the effect of APOE ε4 at the population level

High-sensitivity quantification of acetylcholine and choline in human cerebrospinal fluid with a validated LC-MS/MS method

International audienceAcetylcholine is the neurotransmitter of the parasympathetic nervous system, synthesized from choline and involved in several neurodegenerative diseases. Exploration of cholinergic neurotransmission in the human central nervous system is limited by the lack of a sensitive and specific method for the determination of acetylcholine and choline expression. We developed an hydrophilic interaction liquid chromatography – mass spectrometry method for the quantification of both molecules in human cerebrospinal fluid samples. An extensive selectivity study towards endogenous interfering compounds, in particular γ-butyrobetain, was performed and the method was validated according to the European Medicine Agency and Food and Drug Administration guidelines for the validation of bioanalytical methods. The performance of the method was excellent with a lower limit of quantification at 5 ng/L (34.2 pmol/L) for acetylcholine and 5 μg/L for choline, a precision in the range 1.3–11.9% and an accuracy between 85.2 and 113.1%. This suitability of the method for the quantification of acetylcholine and choline in clinical samples was demonstrated with the analysis of patient cerebrospinal fluid samples. Altogether, this validated method allows the simultaneous quantitative analysis of acetylcholine and choline in human cerebrospinal fluid with high sensitivity and selectivity. It will allow to better characterize the cholinergic neurotransmission in human pathologies and to study the effects of drugs acting on this system

Association between ATN profiles and mortality in a clinical cohort of patients with cognitive disorders

Background: Alzheimer's disease (AD) is the 5th leading cause of death in people 65 years and older. The ATN classification reflects a biological definition of AD pathology with markers of Aβ deposition (A), pathologic tau (T), and neurodegeneration (N). Little is known about the relationship between ATN status and the risk of mortality, leading us to examine this association in a relatively large population of patients seen at a memory clinic for cognitive disorders. Methods: Data were drawn from the BioCogBank Study, including patients seen for cognitive disorders in Lariboisiere Hospital (Paris, France), followed up to 15 years. All participants underwent a lumbar puncture for an assessment of the levels of CSF tau (tau), phosphorylated tau (p-tau181), and β-amyloid 42 peptide (Aβ42). Vital status on July 1, 2020, was recorded for each participant using the national mortality register. Individuals were categorized according to their ATN profiles based on CSF Aβ42 or Aβ42/40 ratio, p-tau181, and tau. Kaplan-Meier and multivariate Cox analyses were performed with A-T-N - participants as the reference using a short (5 years) and long follow-up (15 years). Results: Of the 1353 patients in the study (mean age: 68 years old, 53% of women, mean MMSE score: 22.6), 262 died during the follow-up. At 5 years of follow-up, A-T-N + individuals had the highest risk of mortality in Kaplan-Meier and adjusted Cox analyses [HR (95% CI) = 2.93 (1.31-6.56)]. At 15 years of follow-up, patients in the AD spectrum had a higher mortality risk with a gradient effect for biomarker positivity: A-T + [HR = 1.63 (1.04-2.55)], A + T - [HR = 2.17 (1.44-3.26)], and A + T + individuals [HR = 2.38 (1.66-3.39)], compared to A-T-N - patients. Adjustments on potential confounders had little impact on these associations. Conclusion: This study shows ATN profiles to be associated with mortality in a relatively large patient cohort based on a memory clinic. Patients with isolated evidence of neurodegeneration had a higher mortality rate in the short follow-up, and patients with the AD profile had the highest mortality rate in the long follow-up