BIOMARKER CORE SUMMARY: With the increasing emphasis in the Alzheimer’s Disease (AD) field on molecular diagnosis, the Biomarker Core has two over-arching goals. First, we will continue a highly-successful tradition at the University of Pennsylvania of banking and widely dispersing biofluid samples obtained by the Clinical Core, while annotating these samples with baseline molecular measures that allow for Amyloid-Tau-Neurodegeneration (A/T/(N)) classification within the NIA-AA framework. Second, we will pave new ground by relating well-established CSF- and imaging-based A/T/(N) biomarkers to measures obtained from emerging plasma-based biomarkers, and performing measures that will allow for investigation of the contribution of vascular disease to heterogeneity of clinical phenotype. These goals will be met through activities along five Specific Aims. AIM 1: Oversee and direct all banking and dispersal of biofluid samples obtained in ADRC UDS participants (current n=537). AIM 2: Characterize established biochemical biomarkers previously reported in the literature in order to annotate all Clinical Core samples within the A/T/(N) classification scheme. A CSF biochemical biomarker profile defined by (1) CSF amyloid-beta 1-42 (CSF Aβ42) and (2) 1-40 (CSF Aβ40), (3) CSF total tau (CSF t-tau), (4) CSF tau phosphorylated at residue 181 (CSF p-tau181), (5) CSF neurofilament light chain (CSF NfL), and (6) plasma NfL measures will be established. AIM 3: Relate emerging plasma-based biomarkers to established CSF and imaging biomarkers, as well as neuropathology. We will focus on assays of plasma p-tau and plasma Aβ, validating measures from samples obtained antemortem against postmortem findings. For well-validated assays, we will obtain plasma measures on all ADRC UDS participants. AIM 4: Collaborate with other Cores to investigate the contribution of vascular disease to heterogeneity of clinical phenotype. We will support the collection of biomarker measures (i.e. CRP, cholesterol, hemoglobin A1c, interleukin-6 (IL-6), homocysteine) that allow for assessment of vascular risk in all ADRC UDS participants. AIM 5: Provide advice and support to investigators within and outside the Penn ADRC.