Imaging Research Seeks Early Detection of Alzheimer's Risk

Using a "marker" revealed by functional magnetic resonance imaging (fMRI) brain scans, researchers at the Medical College of Wisconsin are working to create a method to spot patients at high risk for Alzheimer's disease even before they develop symptoms.

The risk marker gleaned from fMRI is called a COSLOF index, which measures very small changes in blood flow in regions of the brain relevant to memory - such as the hippocampus. A pilot study showed that people with mild cognitive impairment scored lower on the index as compared to those with normal cognitive function.

"What we're trying to find is a marker that can identify people at future risk of developing dementia so that pharmacologic interventions can be used before we make the diagnosis of Alzheimer's disease," said Piero G. Antuono, MD, Medical College Professor of Neurology and co-investigator of the study. Principal investigator Shi-Jiang Li, PhD, Professor of Biophysics, developed the technology used to create the COSLOF index.

The Extendicare Foundation funded the pilot research and recently awarded a second grant to support an expanded study to compare the COSLOF values of volunteers both with and without factors thought to influence risk for Alzheimer's.

"Because blood flow is tightly coupled to neuronal activity, we measure blood flow to have an idea of the neuronal activity in that area," said Dr. Antuono. "The two things go hand-in-hand. In the study we're including roughly 50 patients with MCI, the pre-Alzheimer's condition of mild cognitive impairment, 50 patients with Alzheimer's disease, and 50 people over age 65 who have no memory problems."

Individual Assessment: the Sooner the Better
At present, Alzheimer's disease is unpreventable and incurable, severely limiting physical and mental abilities and devastating memory function in about four million people in the US. Given the demographics of an aging population and barring significant breakthroughs in diagnosis and treatment, it is estimated that as many as 14 million people will suffer from the brain disorder by the year 2050.

However, advances in drug development and other interventions are starting to show better results in delaying the onset of the Alzheimer's and in treating symptoms. For both current and future therapy options, the ability to accurately measure pre-clinical risk for individual patients may enable physicians to intervene with good effect before the damage cannot be reversed, Dr. Antuono said.

"The people in our study will have a brain scan every year for five years," said Dr. Antuono. "We are going to look at the MCI population and predict who may develop dementia among that group and who may not develop dementia among that group in five years.

"We feel pretty confident about this, because it's a measure that since our first paper was written has been picked up by several laboratories in the US and in Europe. Other colleagues have extended this marker to other diseases such as head trauma and stroke. I think it offers hope."

A clear assessment of future risk for Alzheimer's will help pinpoint the cause of diminished memory on a case-by-case basis, Dr. Antuono said, adding great value to the role that would be played by a workable technique incorporating fMRI scans and the COSLOF index.

"Number one, it's very difficult to distinguish normal age-related memory loss from memory loss which may be the tip of the iceberg of Alzheimer's disease," said Dr. Antuono. "If the pharmacological intervention to prevent or delay Alzheimer's disease is an intervention which is expensive, risky, fraught with problems, we can't give it to everyone who is 65. We need to identify those among us who should take that risk."

Dan Ullrich
HealthLink Contributing Writer

For more information on this topic, see the HealthLink articles End-Stage Alzheimer’s - the Long Goodbye and New Treatments Brighten Outlook for Alzheimer’s Patients.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.