MRI Technique Reveals Brain Connection Breakdown Specific to Alzheimer’s Disease

Recently, a new study presented at the Annual Meeting of the Radiological Society of North America (RSNA) showed that in brains of patients affected with Alzheimer’s disease, changes in brain connections can be visualized by Magnetic resonance imaging (MRI).

Alzheimer’s disease is currently estimated to affect approximately 5 million Americans and it is the leading cause of dementia in seniors. Preventive measures would allow detection of who is at risk of developing Alzheimer’s disease, such as those suffering from mild cognitive impairment (MCI), and intervene with appropriate therapeutics to delay the disease onset. While early detection was previously reported through detection of the protein beta amyloid, which accumulates in amyloid plaques in Alzheimer’s disease patients’ brains, here the authors mapped brain connections from a structural point of view — a structural connectome.

The team of researchers analyzed brain images from 102 patients who were part of the Alzheimer’s Disease Neuroimaging Initiative (ADNI) study. The patients were submitted to MRI — specifically, a method called diffusion tensor imaging (DTI) that was developed during the 1980s and allows non-invasive mapping of diffusion of molecules such as water in vivo. In this new study, the authors mapped how water diffused in the brain to determine the integrity of white matter tracts. The authors then correlated their imaging of structural connections with the results showing where amyloid beta plaques accumulate in the brain (measured by florbetapir uptake, a PET scanning radiopharmaceutical compound used as a diagnostic tool for Alzheimer’s disease). They found that areas of increased florbetapir uptake, which led to higher amyloid accumulation, correlated with decreased strength of structural connectome.

Thus, this new imaging process may be a potential new technique to determine brain damage and monitor therapeutics’ efficacy in neurodegenerative diseases such as Alzheimer’s.

Study co-author Jeffrey W. Prescott, M.D., Ph.D., radiology resident at Duke University Medical Center in Durham, N.C. noted, “This study ties together two of the major changes in the Alzheimer’s brain–structural tissue changes and pathological amyloid plaque deposition–and suggests a promising role for DTI as a possible diagnostic adjunct.”

Jeffrey R. Petrella, M.D., professor of radiology at Duke and the study’s lead author added, “Traditionally, Alzheimer’s disease is believed to exert its effects on thinking via damage to the brain’s gray matter, where most of the nerve cells are concentrated,” said. “This study suggests that amyloid deposition in the gray matter affects the associated white matter connections, which are essential for conducting messages across the billions of nerve cells in the brain, allowing for all aspects of mental function.”