Brain Imaging May Help Predict Dementia Years Before Symptoms

November 29, 2018

By Megan Brooks

NEW YORK (Reuters Health) - Diffusion-weighted magnetic-resonance imaging (MRI) can help identify older adults who will go on to develop Alzheimer's disease, according to new research.

MRI using diffusion-tensor imaging (DTI) was more accurate in predicting which patients would later develop Alzheimer's disease than standard questionnaires used to measure cognition and tests for APOE4, a gene variant tied to higher risk of Alzheimer's disease.

"This study adds to the literature by detailing an MR imaging analysis that can identify persons who will develop dementia 2.6 years before the symptoms develop. Most of the studies published on imaging are of persons who already have dementia," lead author Dr. Cyrus Raji of the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis told Reuters Health by email.

The findings were presented November 25 at the annual meeting of the Radiological Society of North America (RSNA) in Chicago.

Dr. Raji and colleagues quantified differences in DTI in people who declined from normal cognition to mild cognitive impairment or Alzheimer's dementia compared to controls who did not develop dementia.

They performed DTI exams on 61 adults (mean age, 73; 48% women) participating in the Alzheimer's Disease Neuroimaging Initiative. About half of the patients went on to develop Alzheimer's disease, and DTI identified quantifiable differences in the brains of these patients, Dr. Raji reported.

Specifically, people who developed dementia had lower fractional anisotropy (FA), suggesting damage to the brain's white matter, compared with those who remained cognitively healthy. They also had statistically significant reductions in certain frontal white matter tracts.

"DTI performed very well compared to other clinical measures," Dr. Raji said in a news release from RSNA. "Using FA values and other associated global metrics of white matter integrity, we were able to achieve 89% accuracy in predicting who would go onto develop Alzheimer's disease. The Mini-mental State Examination and APOE4 gene testing have accuracy rates of about 70 to 71%."

In a more detailed analysis of the white matter tracts in about 40 participants, DTI achieved 95% accuracy, Dr. Raji said.

He told Reuters Health, "The clinical implications include selecting patients for better drugs for clinical trials, testing these scans against more sophisticated artificial intelligence methods to see if we can improve the lead time for detection now that we know that they can detect persons who will develop dementia, and potentially one day in a clinical setting as all patients with suspected memory problems get an MRI of the brain."

The study was funded by the Boerger Research Fund for Alzheimer's Disease and Neurocognitive Disorders from the Foundation of the American Society of Neuroradiology. Dr. Raji disclosed no relevant financial relationships.


RSNA 2018.

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