👤 Amanda N Buerger

Cerebrospinal fluid amyloid beta 42, total tau, and phosphorylated tau 181 are well accepted markers of Alzheimer's disease. These biomarkers better reflect disease pathogenesis compared to clinical diagnosis. Here, we perform a genome wide association study meta-analysis including 18,948 individuals of European ancestry and identify 12 genome-wide significant loci across all three biomarkers, eight of them novel. We replicate the association of biomarkers with APOE, CR1, GMNC/CCDC50 and C16orf95/MAP1LC3B. Novel loci include BIN1 for amyloid beta and GNA12, MS4A6A, SLCO1A2 with both total tau and phosphorylated tau 181, as well as additional loci on chr. 8, near ANGPT1 and chr. 9 near SMARCA2. We also demonstrate that these variants have significant association with Alzheimer's disease risk, disease progression and/or brain amyloidosis. The associated genes are implicated in lipid metabolism independent of APOE, coupled with autophagy and brain volume regulation driven by total tau and phosphorylated tau 181 dysregulation. Show less

Early and accurate detection of Alzheimer's disease (AD) is essential for timely intervention and development of disease-modifying treatments. The DZNE-Longitudinal Cognitive Impairment and Dementia Study (DELCODE) provides a deeply phenotyped cohort covering preclinical and early clinical stages, including subjective cognitive decline (SCD) and mild cognitive impairment (MCI). Astrocyte reactivity and its biomarkers, particularly glial fibrillary acidic protein (GFAP), have gained increasing attention in AD research; however, the relationship between GFAP and amyloid in early disease, as well as its potential prognostic value beyond its association with amyloid status, remains insufficiently understood. To evaluate the performance of CSF and plasma GFAP across early disease stages, compare these measures according to amyloid status, and assess the prognostic value of GFAP for clinical progression across diagnostic stages during longitudinal follow-up. This study used data from the multicenter DELCODE cohort in Germany, including participants with available plasma and/or CSF samples and standardized clinical, cognitive, imaging, and biomarker assessments. GFAP concentrations in plasma and CSF were quantified using validated immunoassay platforms. Standard CSF AD biomarkers and ApoE genotype were measured using established assays. Amyloid status was defined by the CSF Aβ42/40 ratio. Longitudinal follow-up occurred annually for up to ∼10 years, with clinical conversion determined according to NIA-AA criteria. Plasma and CSF GFAP increased across the AD continuum, with higher levels in MCI and AD (p < 0.001). Plasma GFAP showed a stronger association with amyloid status than CSF GFAP across all groups. In MCI, plasma GFAP combined with age and ApoE4 yielded an AUC of 0.87. Elevated plasma GFAP predicted increased risk of conversion to MCI (HR = 2.19, p < 0.001; adjusted HR = 1.70, p = 0.0056) and AD dementia (HR = 3.5; adjusted HR = 2.49 both p < 0.001). Plasma GFAP is a sensitive, minimally invasive biomarker with diagnostic relevance for amyloid detection and prognostic relevance for clinical progression in early AD. Show less

Imaging studies showed early atrophy of the cholinergic basal forebrain (BF) already at prodromal stages of sporadic Alzheimer's disease (AD). Women and carriers of the ApoE epsilon 4 (ApoE ε4) allele are more likely to develop the disease; however, the underlying mechanisms are still unclear. Here we aimed at exploring the impact of sex and ApoE ε4 genotype in the AD spectrum on longitudinal measures of the basal forebrain and hippocampus, as a comparison region. We leveraged the German multi-centered study DELCODE and analyzed 712 individuals (median age: 71.25 years, interquartile range [IQR] = 9.22) with follow-up MRI scans (median time: 2.8 years, [IQR] = 1.75). Diagnostic groups comprised cognitively normal ( The hippocampus, but not the basal forebrain, showed significant atrophy over time (Hipp: Our findings did not show the anticipated longitudinal effects of sex and ApoE ε4 on longitudinal basal forebrain volume. Only hippocampal atrophy progressed significantly faster in ApoE ε4 homozygote carriers. This dissociation may reflect stage-dependent neurodegenerative processes, with early basal forebrain vulnerability followed by more rapid hippocampal decline, as well as methodological and sample-related constraints. If replicated, these findings suggest that hippocampal measures may be more sensitive longitudinal biomarkers in ApoE ε4 homozygotes, while sex- and ApoE ε4-related effects on the cholinergic system may be more prominent at earlier disease stages. Show less

Neuroinflammation is central to Alzheimer's disease (AD) pathogenesis, yet its contribution to region-specific brain atrophy remains unclear. We examined whether cerebrospinal fluid (CSF) biomarkers predict longitudinal atrophy in the hippocampus and basal forebrain and mediate the impact of AD pathology. Data from 227 DELCODE participants with baseline CSF measures and longitudinal structural MRI were analyzed. Four latent factors (synaptic, microglia, chemokine/cytokine, complement) were derived to capture shared variance across biomarkers. Latent factors represent unobserved biological domains inferred from related CSF markers. In addition, four single biomarkers (neurogranin, sTREM2, YKL-40, ferritin) were tested separately. Regional atrophy rates were estimated using linear mixed-effects models including biomarker × time, A/T classification, diagnosis, and covariates (age, sex, education, ApoE-ε4). Individual slopes were then entered into mediation models. Higher synaptic latent factor (β = - 0.019, pFDR = 0.021) and YKL-40 (β = - 0.020, pFDR = 0.025) significantly predicted hippocampal atrophy. Only these two markers remained significant after correction for multiple comparisons. Mediation analyses revealed significant indirect effects of the synaptic latent factor and YKL-40 on hippocampal atrophy across all A/T groups. No biomarker was associated with basal forebrain atrophy (pFDR > 0.05). Latent factors captured shared biological variance across related biomarkers and provided a more robust representation of underlying biological domains than single biomarkers. This approach identified synaptic dysfunction and astroglial activation as key links between AD pathology and hippocampal neurodegeneration. These findings highlight synaptic and glial pathways as promising targets for disease-modifying interventions. Show less

CSF biomarkers have immense diagnostic and prognostic potential for Alzheimer disease (AD). However, AD is still diagnosed relatively late in the disease process, sometimes even years after the initial manifestation of cognitive symptoms. Thus, further identification of biomarkers is required to detect related pathology in the preclinical stage and predict cognitive decline. Our study aimed to assess the association of neurogranin and β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) with cognitive decline in individuals with subjective cognitive decline (SCD). We enrolled participants with available neurogranin and BACE1 measurements in CSF from the DELCODE (DZNE-Longitudinal Cognitive Impairment and Dementia, Germany) cohort. The longitudinal change of Preclinical Alzheimer's Cognitive Composite score was assessed as the primary outcome in participants with SCD and controls. The secondary outcome was defined as conversion of SCD to mild cognitive impairment (MCI) during follow-up. Levels of neurogranin, BACE1, and neurogranin/BACE1 ratio across groups were compared by analysis of covariance after adjustment for demographics. The linear mixed-effects model and Cox regression analysis were applied to evaluate their association with cognitive decline and progression of SCD to MCI, respectively. A total of 530 participants (mean age: 70.76 ± 6.01 years, 48.7% female) were analyzed in the study. The rate of cognitive decline was faster in individuals with SCD with higher neurogranin and neurogranin/BACE1 ratio (β = -0.138, SE = 0.065, Our findings suggest that CSF neurogranin and BACE1 begin to change in the preclinical stage of AD and they are associated with clinical progression in individuals with SCD. Show less

The physiology of males and females can be vastly different, complicating interpretation of toxicological and physiological data. The objectives of this study were to elucidate the sex differences in the microbiome-gastrointestinal (GI) transcriptome of adult zebrafish. We compared microbial composition and diversity in both males and females fed the same diet and housed in the same environment. There were no sex-specific differences in weight gain nor gastrointestinal morphology based on histopathology. There was no difference in gut microbial diversity, richness (Shannon and Chao1 index) nor predicted functional composition of the microbiome between males and females. Prior to post-hoc correction, male zebrafish showed higher abundance for the bacterial families Erythrobacteraceae and Lamiaceae, both belonging to the phyla Actinobacteria and Proteobacteria. At the genus level, Lamia and Altererythrobacter were more dominant in males and an unidentified genus in Bacteroidetes was more abundant in females. There were 16 unique differentially expressed transcripts in the gastrointestinal tissue between male and female zebrafish (FDR corrected, p < 0.05). Relative to males, the mRNA expression for trim35-9, slc25a48, chchd3b, csad, and hsd17b3 were lower in female GI while cyp2k6, adra2c, and bckdk were higher in the female GI. Immune and lipid-related gene network expression differed between the sexes (i.e., cholesterol export and metabolism) as well as networks related to gastric motility, gastrointestinal system absorption and digestion. Such data provide clues as to putative differences in gastrointestinal physiology between male and female zebrafish. This study identifies host-transcriptome differences that can be considered when interpreting the microgenderome of zebrafish in studies investigating GI physiology and toxicology of fishes. Show less

Differentiation of adipocytes is a highly regulated process modulated by multiple transcriptional co-activators and co-repressors. JMJD1C belongs to the family of jumonji C (jmjC) domain-containing histone demethylases and was originally described as a ligand-dependent co-activator of thyroid hormone and androgen receptors. Here, we explored the potential role of Jmjd1c in white adipocyte differentiation. To investigate the relevance of Jmjd1c in adipogenesis, murine 3T3-L1 preadipocyte cells with transient knock-down of Jmjd1c (3T3_Jmjd1c) were generated. Depletion of Jmjd1c led to the formation of smaller lipid droplets, reduced accumulation of triglycerides and maintenance of a more fibroblast-like morphology after adipocyte differentiation. Concomitantly, insulin stimulated uptake of glucose and fatty acids was significantly reduced in 3T3_Jmjd1c adipocytes. In line with these observations we detected lower expression of key genes associated with lipid droplet formation (Plin1, Plin4, Cidea) and uptake of glucose and fatty acids (Glut4, Fatp1, Fatp4, Aqp7) respectively. Finally, we demonstrate that depletion of Jmjd1c interferes with mitotic clonal expansion (MCE), increases levels of H3K9me2 (dimethylation of lysine 9 of histone H3) at promotor regions of adipogenic transcription factors (C/EBPs and PPARγ) and leads to reduced induction of these key regulators. In conclusion, we have identified Jmjd1c as a modulator of adipogenesis. Our data suggest that Jmjd1c may participate in MCE and the activation of the adipogenic transcription program during the induction phase of adipocyte differentiation in 3T3-L1 cells. Show less