👤 Vaibhav A Janve

Von Willebrand factor (VWF) and ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, 13) are linked to dementia risk, and limited evidence suggests Vanderbilt Memory and Aging Project cohort participants (n=332, 73±7 years, 59% male) completed serial blood draw, neuropsychological assessment, and brain magnetic resonance imaging over 6.4 years (range 1.4-9.7 years). Baseline plasma VWF and ADAMTS13 levels were quantified using mass spectrometry and Olink. Fully adjusted linear mixed-effects models related Lower baseline ADAMTS13 predicted faster declines in language (β=0.11, ADAMTS13 shows promise as a potential plasma biomarker for brain aging outcomes, but additional research is warranted to understand the performance of VWF in the presence versus absence of an Show less

Amyloid deposition occurs decades before symptoms emerge in Alzheimer's disease (AD). We leveraged blood transcriptomics and positron emission tomography (PET) measures of amyloidosis to identify gene networks in the blood that relate to amyloid burden in the brain. Whole-blood RNA sequencing and amyloid PET were leveraged from 1739 cognitively unimpaired participants in the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) study. Linear regression related gene module expression to amyloid covarying for age, sex, education, and apolipoprotein E (APOE) ε2 and ε4 genotypes. Of the 18 gene modules, one histone gene cluster module was associated with amyloid (β = -0.55, false discovery rate-adjusted p value = 0.029). We also observed nominal associations for the predicted proportion of activated natural killer (NK) cells (β = -0.454, p = 0.02) and CD4+ activated memory T cells (β = -0.169, p = 0.03) with amyloid deposition. Our results implicate the histone gene cluster on chromosome 6 and immune cell proportions as blood correlates of brain amyloid deposition in preclinical AD. Higher expression of network module with histone gene cluster on chromosome 6 associated with lower amyloid levels. Four histone genes, H1-5, H3C3, H2BC3, H2AC14, and RRM2, emerged as key genes driving this association, where H1-5 emerged as a hub gene for this module. Pathways, including nucleosome assembly and DNA damage, were enriched in the histone module. A higher fraction of activated NK and activated CD4+ T cells was related to lower amyloid burden. Show less

New methods estimate amyloid positivity onset age (EAOA) from amyloid positron emission tomography (PET). We explore the genetics of EAOA to identify molecular factors underlying the earliest Alzheimer's disease (AD) changes. Harmonized amyloid PET data from 4216 participants were used in genome-wide survival, tissue-specific gene expression, and genetic covariance analyses of EAOA. Variants in apolipoprotein E (APOE), ABCA7, and RASGEF1C associated with earlier EAOA. APOE ε4/ε4 and ε3/ε4 converted 6.3 and 5 years earlier than ε3/ε3, respectively. ε2 was protective against earlier EAOA. rs4147929, an expression quantitative trait locus for ABCA7, associated with a 4 year earlier EAOA. This variant was associated with lower brain expression of ABCA7, which was associated with increased amyloid pathology at autopsy. Multiple immune-related diseases shared genetic covariance with EAOA. APOE, ABCA7, and RASGEF1C associated with earlier EAOA, with supporting evidence from tissue-specific expression analyses, offering insights into intervenable targets at early stages of AD. Novel methods estimate how long ago a patient converted to amyloid positivity. Estimating this amyloid clock allows us to determine the onset of the earliest Alzheimer's disease changes. We evaluated what genes influence when someone converts to amyloid positivity. Apolipoprotein E (APOE), ABCA7, and RASGEF1C associated with earlier age of amyloid positivity. Genetic results were supported by tissue-specific expression analyses. Show less