A new MR imaging technique used to study white matter in the brain has found something intriguing–the brains of Alzheimer’s patients show some of the same signs as the immature brains of children.
Diffusion tensor MR imaging examinations were performed on 60 normal persons, ranging in age from infancy to late adulthood, says Jeffrey Lassig, MD, of the University of Michigan, and lead author of the study. The part of the brain that connects the two halves of the brain was studied. When the brain is immature the water molecules in the white matter of the brain move (diffuse) more freely. As the brain ages, the water molecules seem more constrained, he says.
“When we compared 13 Alzheimer’s patients’ brains to 13 others of the same age with no signs of dementia, the Alzheimer’s patients’ brains showed significantly higher water molecule diffusion.
In other words, the Alzheimer’s patients’ white matter behaved more like the white matter of a child’s brain than that of a normal adult,” says Dr. Lassig. However, the increased diffusion in Alzheimer’s patients is most likely related to damage or dysfunction of axons (white matter tracts), while the higher water diffusion in the white matter of children is a normal phenomenon in immature brains, he says.
Diffusion tensor MR imaging is a new technique which may help physicians find white matter disease earlier in dementia, perhaps even before symptoms are obvious, notes Dr. Lassig. “This technique could also take us a step closer to determining the cause of Alzheimer’s disease,” he adds. Currently, the death of neurons in the brain is suspected as the cause of symptoms in Alzheimer’s disease, with white matter damage a secondary consequence of the neurons dying. No-one knows for sure, and this issue needs further study, Dr. Lassig says.
“This new technique, when used in combination with imaging to specifically evaluate the death of neurons, may provide new information about how the two processes interact,” says Dr. Lassig.
Dr. Lassig will present the study on May 7 during the American Roentgen Ray Society Annual Meeting in San Diego.