Study connects vascular health to early Alzheimer’s brain changes

Subtle changes in how blood flows through the brain and how brain tissue uses oxygen may be closely linked to Alzheimer's disease risk, according to new research from the Mark and Mary Stevens Neuroimaging and Informatics Institute (Stevens INI) at the Keck School of Medicine of USC.

In a study published in Alzheimer's and Dementia: The Journal of the Alzheimer's Association, Stevens INI researchers found that noninvasive measures of brain blood flow and oxygenation were associated with hallmark brain changes in older adults with and without cognitive impairment, including amyloid buildup and a smaller hippocampus, a region essential for memory. The findings suggest that vascular health of the brain may play an important role early in the disease process and could help identify individuals at risk before significant symptoms appear.

Amyloid and tau are often considered the primary players in Alzheimer's disease, but blood flow and oxygen delivery are also critical. Our results show that when the brain's vascular system functions more like it does in healthy aging, we also see brain features that are linked to better cognitive health."

The research team used two noninvasive tools that can be applied while a person rests quietly. Transcranial Doppler ultrasound measures how fast blood moves through major brain arteries, while near-infrared spectroscopy measures how well oxygen reaches brain tissue near the surface of the cortex. Advanced mathematical models were then used to summarize these signals into indicators that reflect how well the brain adjusts blood flow and oxygen delivery in response to natural changes in blood pressure and carbon dioxide levels.