Blood-Based Biomarkers and Risk of Onset of Mild Cognitive Impairment Over the Short and Long Term.

Background And Objectives: Blood-based biomarkers of amyloid and tau have been shown to predict Alzheimer disease (AD) dementia. Much less is known about their ability to predict risk of mild cognitive impairment (MCI), an earlier disease stage. This study examined whether levels of blood biomarkers of amyloid (Aβ/Aβ ratio), tau (p-tau), neurodegeneration (NfL), and glial activation and neuroinflammation (glial fibrillary acidic protein [GFAP], YKL40, soluble triggering receptor expressed on myeloid cells 2 [sTREM2]) collected when participants were cognitively normal are associated with the time to onset of MCI.

Independent associations of sleep and physical activity with cognition are mediated by hippocampal microstructure in middle-aged and older adults.

Sleep and physical activity levels are both associated with cognitive performance among older adults; however, the brain mechanisms underlying these beneficial relationships remain poorly understood. This study investigated cross-sectional associations of actigraphic estimates of physical activity and sleep with cognition and diffusion imaging-based measures of medial temporal lobe (MTL) gray matter microstructural integrity in adults free of dementia. Participants were 132 older adults from the Biomarkers of Cognitive Decline Among Normal Individuals (BIOCARD) cohort study (119 cognitively unimpaired and 13 with mild cognitive impairment; mean age=70.

Acceleration of Brain Atrophy and Progression From Normal Cognition to Mild Cognitive Impairment.

Importance: It remains unclear which risk factors accelerate brain atrophy along with a progression from normal cognition to mild cognitive impairment (MCI).

Objective: To examine risk factors associated with the acceleration of brain atrophy and progression from normal cognition to MCI based on long-term longitudinal data for middle-aged and older adults.

Design, Setting, And Participants: Data for this cohort study were extracted from the Biomarkers for Older Controls at Risk for Dementia (BIOCARD) cohort, initiated at the National Institutes of Health from January 1, 1995, to December 31, 2005, and continued at Johns Hopkins University from January 1, 2015, to October 31, 2023.

Alzheimer's disease genetic risk and changes in brain atrophy and white matter hyperintensities in cognitively unimpaired adults.

Reduced brain volumes and more prominent white matter hyperintensities on MRI scans are commonly observed among older adults without cognitive impairment. However, it remains unclear whether rates of change in these measures among cognitively normal adults differ as a function of genetic risk for late-onset Alzheimer's disease, including -ɛ4, -ɛ2 and Alzheimer's disease polygenic risk scores (AD-PRS), and whether these relationships are influenced by other variables. This longitudinal study examined the trajectories of regional brain volumes and white matter hyperintensities in relationship to genotypes ( = 1541) and AD-PRS ( = 1093) in a harmonized dataset of middle-aged and older individuals with normal cognition at baseline (mean baseline age = 66 years, SD = 9.