MRI scans identify differences between Alzheimer’s disease converters, non-converters

Researchers identified quantifiable differences between older adults who developed Alzheimer’s disease and those who did not using diffusion weighted MRI.

The study, presented at the Radiological Society of North America annual meeting, reported that MRI brain scans also performed better than common clinical tests at predicting which people developed Alzheimer's disease.

"Alzheimer's disease is the most common cause of dementia in the world and is expected to increase globally, and especially in the U.S., as the population gets older," Cyrus A. Raji, MD, PhD, assistant professor of radiology at the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis, said in a press release. "As we develop new drug therapies and study them in trials, we need to identify individuals who will benefit from these drugs earlier in the course of the disease.”

In their study, Raji and colleagues calculated differences in diffusion tensor imaging — which provides different metrics of white matter integrity — of 61 older adults enrolled in the Alzheimer’s Disease Neuroimaging Initiative study. They also extracted fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity values.

Roughly 50% of patients developed Alzheimer's disease and diffusion tensor imaging detected differences in these patients compared with those who did not develop the disease, according to the press release. Older adults who developed Alzheimer’s disease had lower fractional anisotropy compared with those who did not, which could indicate white matter damage, and they also had statistically significant decreases in some frontal white matter tracts, the release said.

Using fractional anisotropy values and other associated global metrics of white matter integrity achieved 89% accuracy in predicting who would develop Alzheimer's disease, Raji said in the release. Comparatively, the Mini-mental State Examination and APOE4 gene testing have accuracy rates of about 70%, he added.

In addition, after conducting further analysis of the white matter tracts in about 40 of the study participants, Raji and colleagues found that diffusion tensor imaging achieved 95% accuracy.

"[Diffusion tensor imaging] performed very well compared to other clinical measures. Research shows that Alzheimer's disease risk can be reduced by addressing modifiable risk factors like obesity and diabetes," Raji said in the release. "With early detection, we can enact lifestyle interventions and enlist volunteers into drug trials earlier." – by Savannah Demko

References:

Raji CA, et al. Tract based spatial statistics in persons who will develop Alzheimer's dementia: A study from the Alzheimer's Disease Neuroimaging Initiative (ADNI). Presented at: Radiological Society of North America 2018 104th Scientific Assembly and Annual Meeting; Nov. 25-30, 2018; Chicago.

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