A new small study suggests magnetic resonance imaging of the brain could one day help predict—before symptoms arise—whether an older person will develop dementia.
Research conducted at Washington University School of Medicine in St. Louis and the University of California San Francisco used brain scans to predict with 89% accuracy who would go on to develop dementia within 3 years. The findings were recently presented at the Radiological Society of North America meeting in Chicago, Illinois.
“Right now it’s hard to say whether an older person with normal cognition or mild cognitive impairment is likely to develop dementia,” said lead author Cyrus A. Raji, MD, PhD, an assistant professor of radiology at Washington University’s Mallinckrodt Institute of Radiology. “We showed that a single MRI scan can predict dementia on average 2.6 years before memory loss is clinically detectable, which could help doctors advise and care for their patients.”
In the study, the Mini-Mental State Examination and tests for the high-risk form of the gene ApoE, were only about 70 to 80 percent accurate.
Researchers used diffusion tensor imaging to assess the health of the brain’s white matter.
“Diffusion tensor imaging is a way of measuring the movement of water molecules along white matter tracts,” Raji said. “If water molecules are not moving normally it suggests underlying damage to white tracts that can underlie problems with cognition.”
The study team identified 10 people whose cognitive skills declined over a two-year period and matched them by age and sex with 10 people whose thinking skills had held steady. The people in each group had an average age of 73 years. Then, the researchers analyzed diffusion tensor MRI scans taken just before the two-year period for all 20 people, and found that people in the cognitive decline group had significantly more signs of damage to their white matter.
The analysis was repeated in a separate sample of 61 people, using a more refined measure of white matter integrity. Data from that stage was 89% accurate when looking at the whole brain, and 95% accurate when focusing on parts of the brain most likely to show damage.