PROJECT SUMMARY / ABSTRACT
Late-life Alzheimer’s disease and related dementias (ADRD) are devastating multifactorial conditions and the
major contributors to loss of independence in older age. There is a critical unmet need to identify which
individuals are at the great risk of these conditions, thus permitting accurate prognosis and timely preventative
interventions to reduce the burden. Yet, while several risk factors have been identified for these conditions, sex
differences in these associations have rarely been considered. Furthermore, exciting recent advances in blood
amyloid, tau and neurodegeneration (AT(N)) biomarkers for ADRD means that they could soon be used as
powerful clinical diagnostic and prognostic tools in a personalized medicine approach. However, critical multiple
knowledge gaps remain. Importantly, 1) these biomarkers have not been sufficiently examined in longitudinal
studies of older community- based populations without diagnosed dementia; 2) it is unclear how participant
characteristics such as comorbidities affect the clinical interpretation of these biomarkers; and 3) how their
interpretation may differ between men and women. Together, these large knowledge gaps highlight a crucial
need to develop the first sex-specific risk score for ADRD that incorporates blood AT(N) biomarkers and ADRD
risk factors. Our overarching hypothesis is that AT(N) plasma biomarkers will be predictive of ADRD in initially
healthy community-dwelling older individuals, beyond known risk factors (including age, education, living alone,
diabetes, hypertension, smoking, alcohol consumption, physical activity), and that these associations will vary
by sex. This project provides an unprecedented opportunity to address this important question within the
context of a rigorous, large-scale study of initially healthy individuals aged 65-98 years from the US and Australia
(12,716 whites, 412 blacks, 339 other minorities) with comprehensive annual in-person cognitive assessments,
adjudicated clinical outcomes, detailed data on socio-economic status, lifestyle and health factors collected over
a median 9+ years, and existing genetic data (APOE4, dementia polygenic risk scores). Leveraging unique blood
samples available at two time-points (n=13,435 at baseline, and ~8000 at 7 to 10 years), AT(N) biomarkers will
be measured longitudinally. This proposal is a unique, highly cost-efficient opportunity to address gaps in our
ability to accurately determine who is at the greatest risk of ADRD, individually for women and men. We will
address critical gaps in identifying which factors influence blood biomarker levels and must be considered when
establishing their clinical reference ranges. The sex-specific risk score resulting from this project will provide a
powerful new tool for practitioners to predict risk of cognitive decline and ADRD that considers common
comorbidities, social, lifestyle, and genomic risk factors, together with the unique predictive strength of the
plasma AT(N) biomarkers.