Early diagnosis of Alzheimers may be realized with fMRI

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Functional magnetic resonance imaging (fMRI) may reveal a marker for early diagnosis of Alzheimer's disease, according to a study published in the October issue of Radiology.

“The findings of this study implicate a potential functional, rather than structural, brain marker, separate from atrophy, that may help enhance diagnosis and treatment monitoring of Alzheimer's patients,” said the study’s lead author, Jeffrey Petrella, MD, associate professor of radiology at Duke University Medical Center in Durham, N.C.

Researchers studied 13 patients with mild Alzheimer's disease, 34 patients with mild cognitive impairment and 28 healthy controls. The study group contained 37 men and 38 women with a mean age of 73. After completing neuropsychological testing, the participants were monitored with fMRI while performing a memory task.

The study results showed that across the study group spectrum, from healthy people at low risk, to people with mild memory problems, to patients with Alzheimer's disease, there was increasingly impaired activation in the medial temporal lobe (MTL), a brain area associated with episodic memory that activates during a memory task.

The researchers were surprised to find increasingly impaired deactivation in the posteromedial cortices (PMC), an area recently implicated with personal memory that normally suppresses its activity during a memory task. The deactivation in the PMC was closely related to the level of memory impairment in the patients, which correlated with their neuropsychological testing scores.

While previous studies have suggested that MTL activation may be a possible marker of Alzheimer's disease, Petrella and colleagues concluded that compared to MTL activation, deactivation in the PMC may represent a more sensitive marker of early Alzheimer's.

“The next step is to conduct a large, multicenter study to see if fMRI can be combined with other imaging and genetic tests to scan for future disease,” said study co-author P. Murali Doraiswamy, MD, chief of the Division of Biological Psychiatry at Duke.