Measuring Brain Connectivity As a New Alzheimer’s Biomarker

What: Using MRI to measure functional connectivity across various networks in the brain, researchers were able to predict the onset of Alzheimer’s disease (AD).

Where: Smith et. al, “Resting-State Functional Connectivity Disruption as a Pathological Biomarker in Autosomal Dominant Alzheimer Disease,” Brain Connect, 2021.

BrightFocus Connection: This project was supported by an Alzheimer’s Disease Research (ADR) grant to Jeremy Strain, PhD and mentor, Beau Ances, MD, PhD, MSc of Washington University School of Medicine. Dr. Ances also serves as a longtime member of the ADR Scientific Review Committee.

Why it is Important: Researchers have long performed functional magnetic resonance imaging (MRI) to investigate regional interactions in the brain. In the absence of a goal directed task, the brain continues to display organized patterns of synchronicity between specific brain regions resulting in “resting state networks,” where segregated, specialized information is transferred. By imaging the brain’s resting state functional connectivity, doctors can determine how neurological or psychiatric diseases may disrupt vital brain connections. Previous studies have focused on functional connectivity within a single network of the brain. However, this project focused on mapping patterns in the functional connectivity within and between various networks across the brain. Using this technique, this research team has brought the field closer to being able to pre-emptively predict and combat AD in people who are genetically predisposed to early onset forms of the disease, and perhaps in other patients.

The researchers compared the resting-state functional connectivity of 171 people genetically predisposed to AD (mutation carriers) with that of 70 people without the genetic mutations associated with the disease (non-carriers). The researchers found that the people carrying genetic mutations for Alzheimer’s had poorer resting state functional connectivity than those without genetic mutations. They also found that the more advanced a patient’s Alzheimer’s was, the more disruption could be seen in their resting-state functional connectivity.

These findings indicate that internal disruptions in resting state networks are associated with AD and become worse as the disease progresses. These results also suggest that prior studies primarily focusing on changes within a single network may overlook important changes between networks across the brain. In the future, physicians and researchers could potentially use this technique of mapping functional connectivity across resting state networks as a biomarker of AD onset, and it might also be useful as a benchmark reading among clinical trial participants that can then be used to evaluate treatment efficacy.