New MRI Technique May Predict Progress of Dementias

New technology for evaluating brain images offers the potential of employing magnetic resonance imaging (MRI) to predict the rate of progression and physical path of many deteriorating brain disorders.

The technique, developed by San Francisco Veteran’s Administration (VA) Medical Center (SFVAMC; CA, USA) scientists in collaboration with a team led by Bruce Miller, MD, clinical director of the University of California, San Francisco (UCSF) Memory and Aging Center (USA), also supports growing data that dementias spread through the brain along specific neuronal pathways in the same manner as prion diseases.

The scientists employed new computer modeling techniques to predict realistically the physical progression of Alzheimer’s disease (AD) and frontotemporal dementia (FTD) using images of 14 healthy brains. The models were based on whole-brain tractography, an MRI technique that maps the neural pathways that connect different areas of the brain. The spread of disease along those pathways, as predicted by the models, closely correlated with actual MR images of brain degeneration in 18 AD patients and 18 FTD patients.

The study’s findings were published in the March 22, 2012, issue of the journal of Neuron. “The results need to be replicated, but they suggest that, by using this approach, we can predict the location and course of future brain atrophy in Alzheimer’s, FTD, and other degenerative brain diseases, based on just one MRI taken at the outset of the disease,” said senior author Michael Weiner, MD, director of the SFVAMC Center for Imaging of Neurodegenerative Diseases. “This would be extremely useful in planning treatment, and in helping patients and families know what to expect as dementia progresses.”

Dr. Weiner, who is also a UCSF professor of radiology, medicine, psychiatry, and neurology, reported that that the findings were “consistent with an emerging concept that brain damage occurs in these neurodegenerative diseases in a diffusive, prion-like propagation.”

A prion is an infectious, misfolded form of a normal protein. These proteins leave destructive amyloid deposits in the brains in which they develop, causing degeneration and eventual death. They are responsible for Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy (mad cow disease), in cattle.

“The idea of a prion-like mode of progression in dementias, which many scientists are beginning to support, is that the misfolded protein in one neuron will infect a neighboring brain cell, causing proteins in that cell to misfold in turn, and that the spread of these misfolded proteins flows along certain networks in the brain,” explained Dr. Weiner. “For instance, in Alzheimer’s, there is a spread of amyloid protein along the memory network. This paper reinforces the idea that the damage occurs progressively along that network and others.”

Dr. Weiner emphasized that Alzheimer’s and frontotemporal dementia “are not infectious diseases” such as Creutzfeldt-Jakob. But he said, “it may be that a little seed of the disease begins in one neuron in the brain and spreads in a similar way--so it’s infectious within the brain, from one neuron to the next.”

Related Links:
San Francisco VA Medical Center
University of California, San Francisco Memory and Aging Center